The Event Horizon Telescope (EHT) collaboration has produced the first resolved images of M87*, the supermassive black hole at the centre of the elliptical galaxy M87. As both technology and analysis pipelines improve, it will soon become possible to produce spectral index maps of black hole accretion flows on event horizon scales. In this work, we predict spectral index maps of both M87* and Sgr A* by applying the general relativistic radiative transfer (GRRT) code {\sc ipole} to a suite of general relativistic magnetohydrodynamic (GRMHD) simulations. We analytically explore how the spectral index increases with increasing magnetic field strength, electron temperature, and optical depth. Consequently, spectral index maps grow more negative with increasing radius in almost all models, since all of these quantities tend to be maximized near the event horizon. Additionally, photon ring geodesics exhibit more positive spectral indices, since they sample the innermost regions of the accretion flow with the most extreme plasma conditions. Spectral index maps are sensitive to highly uncertain plasma heating prescriptions (the electron temperature and distribution function). However, if our understanding of these aspects of plasma physics can be tightened, even the spatially unresolved spectral index around 230 GHz can be used to discriminate between models. In particular, Standard and Normal Evolution (SANE) flows tend to exhibit more negative spectral indices than Magnetically Arrested Disk (MAD) flows due to differences in the characteristic magnetic field strength and temperature of emitting plasma.
01903nas a2200169 4500000000100000000000100001008004100002100002200043700002100065700001900086700002900105700001900134700002200153245008400175856003700259520143700296 d 1 aJoshua Yao-Yu Lin 1 aDominic W. Pesce 1 aGeorge N. Wong 1 aAjay Uppili Arasanipalai 1 aBen S. Prather 1 aCharles F. Gammie 00 aVLBInet: Radio Interferometry Data Classification for EHT with Neural Networks uhttps://arxiv.org/abs/2110.07185 3 aThe Event Horizon Telescope (EHT) recently released the first horizon-scale images of the black hole in M87. Combined with other astronomical data, these images constrain the mass and spin of the hole as well as the accretion rate and magnetic flux trapped on the hole. An important question for the EHT is how well key parameters, such as trapped magnetic flux and the associated disk models, can be extracted from present and future EHT VLBI data products. The process of modeling visibilities and analyzing them is complicated by the fact that the data are sparsely sampled in the Fourier domain while most of the theory/simulation is constructed in the image domain. Here we propose a data-driven approach to analyze complex visibilities and closure quantities for radio interferometric data with neural networks. Using mock interferometric data, we show that our neural networks are able to infer the accretion state as either high magnetic flux (MAD) or low magnetic flux (SANE), suggesting that it is possible to perform parameter extraction directly in the visibility domain without image reconstruction. We have applied VLBInet to real M87 EHT data taken on four different days in 2017 (April 5, 6, 10, 11), and our neural networks give a score prediction 0.52, 0.4, 0.43, 0.76 for each day, with an average score 0.53, which shows no significant indication for the data to lean toward either the MAD or SANE state.
01703nas a2200169 4500000000100000000000100001008004100002100001100043700002400054700001500078700001800093700001600111700001800127245014900145856003700294520120200331 d 1 aHe Sun 1 aKatherine L. Bouman 1 aPaul Tiede 1 aJason J. Wang 1 aSarah Blunt 1 aDimitri Mawet 00 aalpha-Deep Probabilistic Inference (alpha-DPI): efficient uncertainty quantification from exoplanet astrometry to black hole feature extraction uhttps://arxiv.org/abs/2201.08506 3 aInference is crucial in modern astronomical research, where hidden astrophysical features and patterns are often estimated from indirect and noisy measurements. Inferring the posterior of hidden features, conditioned on the observed measurements, is essential for understanding the uncertainty of results and downstream scientific interpretations. Traditional approaches for posterior estimation include sampling-based methods and variational inference. However, sampling-based methods are typically slow for high-dimensional inverse problems, while variational inference often lacks estimation accuracy. In this paper, we propose alpha-DPI, a deep learning framework that first learns an approximate posterior using alpha-divergence variational inference paired with a generative neural network, and then produces more accurate posterior samples through importance re-weighting of the network samples. It inherits strengths from both sampling and variational inference methods: it is fast, accurate, and scalable to high-dimensional problems. We apply our approach to two high-impact astronomical inference problems using real data: exoplanet astrometry and black hole feature extraction.
02086nas a2200133 4500000000100000000000100001008004100002100002900043245007800072856004500150300000700195490000800202520174200210 2022 d 1 aet Kaushik Satapathy al. 00 aThe Variability of the Black Hole Image in M87 at the Dynamical Timescale uhttps://doi.org/10.3847/1538-4357/ac332e a13 0 v925 3 aThe black hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5–61 days) is comparable to the 6 day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferometric observables that are sensitive to the expected structural changes of the images but are free of station-based atmospheric and instrumental errors. We explored the day-to-day variability in closure-phase measurements on all six linearly independent nontrivial baseline triangles that can be formed from the 2017 observations. We showed that three triangles exhibit very low day-to-day variability, with a dispersion of ∼3°–5°. The only triangles that exhibit substantially higher variability (∼90°–180°) are the ones with baselines that cross the visibility amplitude minima on the u–v plane, as expected from theoretical modeling. We used two sets of general relativistic magnetohydrodynamic simulations to explore the dependence of the predicted variability on various black hole and accretion-flow parameters. We found that changing the magnetic field configuration, electron temperature model, or black hole spin has a marginal effect on the model consistency with the observed level of variability. On the other hand, the most discriminating image characteristic of models is the fractional width of the bright ring of emission. Models that best reproduce the observed small level of variability are characterized by thin ring-like images with structures dominated by gravitational lensing effects and thus least affected by turbulence in the accreting plasmas. 01725nas a2200277 4500000000100000000000100001008004100002100001900043700001900062700001700081700002100098700002500119700001800144700002200162700001800184700001900202700002000221700002200241700001900263700002500282700002200307245007500329856004500404490000800449520099000457 2022 d 1 aGeorge N. Wong 1 aBen S. Prather 1 aVedant Dhruv 1 aBenjamin R. Ryan 1 aMonika Mościbrodzka 1 aChi-Kwan Chan 1 aAbhishek V. Joshi 1 aRicardo Yarza 1 aAngelo Ricarte 1 aHotaka Shiokawa 1 aJoshua C. Dolence 1 aScott C. Noble 1 aJonathan C. McKinney 1 aCharles F. Gammie 00 aPATOKA: Simulating Electromagnetic Observables of Black Hole Accretion uhttps://doi.org/10.3847/1538-4365/ac582e 0 v259 3 aThe Event Horizon Telescope (EHT) has released analyses of reconstructed images of horizon-scale millimeter emission near the supermassive black hole at the center of the M87 galaxy. Parts of the analyses made use of a large library of synthetic black hole images and spectra, which were produced using numerical general relativistic magnetohydrodynamics fluid simulations and polarized ray tracing. In this article, we describe the PATOKA pipeline, which was used to generate the Illinois contribution to the EHT simulation library. We begin by describing the relevant accretion systems and radiative processes. We then describe the details of the three numerical codes we use, iharm, ipole, and igrmonty, paying particular attention to differences between the current generation of the codes and the originally published versions. Finally, we provide a brief overview of simulated data as produced by PATOKA and conclude with a discussion of limitations and future directions. 02098nas a2200145 4500000000100000000000100001008004100002100002500043700001900068245008200087856004500169300000700214490000800221520172300229 2022 d 1 aDaniel C. M. Palumbo 1 aGeorge N. Wong 00 aPhoton Ring Symmetries in Simulated Linear Polarization Images of Messier 87* uhttps://doi.org/10.3847/1538-4357/ac59b4 a49 0 v929 3 aThe Event Horizon Telescope (EHT) recently released the first linearly polarized images of the accretion flow around the supermassive black hole Messier 87*, hereafter M87*. The spiraling polarization pattern found in the EHT images favored magnetically arrested disks as the explanation for the EHT image. With next-generation improvements to very long baseline interferometry on the horizon, understanding similar polarized features in the highly lensed structure known as the "photon ring," where photons make multiple half orbits about the black hole before reaching the observer, will be critical to the analysis of future images. Recent work has indicated that this image region may be depolarized relative to more direct emission. We expand this observation by decomposing photon half orbits in the EHT library of simulated images of the M 87* accretion system and find that images of magnetically arrested disk simulations show a relative depolarization of the photon ring attributable to destructive interference of oppositely spiraling electric field vectors; this antisymmetry, which arises purely from strong gravitational lensing, can produce up to ∼50% depolarization in the photon ring region with respect to the direct image. In systems that are not magnetically arrested and with the exception of systems with high spin and ions and electrons of equal temperature, we find that highly lensed indirect subimages are almost completely depolarized, causing a modest depolarization of the photon ring region in the complete image. We predict that next-generation EHT observations of M 87* polarization should jointly constrain the black hole spin and the underlying emission and magnetic field geometry. 01635nas a2200169 4500000000100000000000100001008004100002100001700043700001800060700001900078700001700097700002200114245008100136300000700217490000800224520123300232 2022 d 1 aLia Medeiros 1 aChi-Kwan Chan 1 aRamesh Narayan 1 aFeryal Özel 1 aDimitrios Psaltis 00 aBrightness Asymmetry of Black Hole Images as a Probe of Observer Inclination a46 0 v924 3 aThe Event Horizon Telescope recently captured images of the supermassive black hole in the center of the M87 galaxy, which shows a ring-like emission structure with the south side only slightly brighter than the north side. This relatively weak asymmetry in the brightness profile along the ring has been interpreted as a consequence of the low inclination of the observer (around 17° for M87), which suppresses the Doppler beaming and boosting effects that might otherwise be expected due to the nearly relativistic velocities of the orbiting plasma. In this work, we use a large suite of general relativistic magnetohydrodynamic simulations to reassess the validity of this argument. By constructing explicit counterexamples, we show that low inclination is a sufficient but not necessary condition for images to have low brightness asymmetry. Accretion flow models with high accumulated magnetic flux close to the black hole horizon (the so-called magnetically arrested disks) and low black hole spins have angular velocities that are substantially smaller than the orbital velocities of test particles at the same location. As a result, such models can produce images with low brightness asymmetry even when viewed edge on. 02069nas a2200349 4500000000100000000000100001008004100002100001700043700001800060700002100078700002400099700002200123700001700145700002000162700002000182700001700202700002300219700001800242700002200260700002000282700001900302700002100321700001500342700001900357700001900376700004600395245005600441856004500497300000900542490000800551520116000559 2022 d 1 aJoseph Farah 1 aPeter Galison 1 aKazunori Akiyama 1 aKatherine L. Bouman 1 aGeoffrey C. Bower 1 aAndrew Chael 1 aAntonio Fuentes 1 aJosé L. Gómez 1 aMareki Honma 1 aMichael D. Johnson 1 aYutaro Kofuji 1 aDaniel P. Marrone 1 aKotaro Moriyama 1 aRamesh Narayan 1 aDominic W. Pesce 1 aPaul Tiede 1 aMaciek Wielgus 1 aGuang-Yao Zhao 1 aThe Event Horizon Telescope Collaboration 00 aSelective Dynamical Imaging of Interferometric Data uhttps://doi.org/10.3847/2041-8213/ac6615 a1-21 0 v930 3 aRecent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky. The sparse nature of the EHT's (u, v)-coverage presents a challenge when attempting to resolve highly time-variable sources. We demonstrate that the changing (u, v)-coverage of the EHT can contain regions of time over the course of a single observation that facilitate dynamical imaging. These optimal time regions typically have projected baseline distributions that are approximately angularly isotropic and radially homogeneous. We derive a metric of coverage quality based on baseline isotropy and density that is capable of ranking array configurations by their ability to produce accurate dynamical reconstructions. We compare this metric to existing metrics in the literature and investigate their utility by performing dynamical reconstructions on synthetic data from simulated EHT observations of sources with simple orbital variability. We then use these results to make recommendations for imaging the 2017 EHT Sgr A* data set. 02935nas a2200469 4500000000100000000000100001008004100002100001900043700002000062700002300082700002300105700002800128700001500156700001700171700001700188700002100205700002000226700001800246700001800264700001700282700002400299700002700323700002200350700001800372700002300390700002000413700001700433700002400450700001900474700001700493700002300510700002200533700001800555700002200573700001900595700004600614245010400660856004500764300000900809490000800818520163900826 2022 d 1 aMaciek Wielgus 1 aNicola Marchili 1 aIván Martí-Vidal 1 aGarrett K. Keating 1 aVenkatessh Ramakrishnan 1 aPaul Tiede 1 aSara Issaoun 1 aJoey Neilsen 1 aMichael A. Nowak 1 aLindy Blackburn 1 aCiriaco Goddi 1 aDaryl Haggard 1 aDaeyoung Lee 1 aMonika Moscibrodzka 1 aAlexandra J. Tetarenko 1 aGeoffrey C. Bower 1 aChi-Kwan Chan 1 aKoushik Chatterjee 1 aPaul M. Chesler 1 aJason Dexter 1 aSheperd S. Doeleman 1 aBoris Georgiev 1 aMark Gurwell 1 aMichael D. Johnson 1 aDaniel P. Marrone 1 aAlejandro Mus 1 aDimitrios Psaltis 1 aGunther Witzel 1 aThe Event Horizon Telescope Collaboration 00 aMillimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign uhttps://doi.org/10.3847/2041-8213/ac6428 a1-32 0 v930 3 aThe Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A*), in the Galactic Center on 2017 April 5-11 in the 1.3 mm wavelength band. At the same time, interferometric array data from the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array were collected, providing Sgr A* light curves simultaneous with the EHT observations. These data sets, complementing the EHT very long baseline interferometry, are characterized by a cadence and signal-to-noise ratio previously unattainable for Sgr A* at millimeter wavelengths, and they allow for the investigation of source variability on timescales as short as a minute. While most of the light curves correspond to a low variability state of Sgr A*, the April 11 observations follow an X-ray flare and exhibit strongly enhanced variability. All of the light curves are consistent with a red-noise process, with a power spectral density (PSD) slope measured to be between -2 and -3 on timescales between 1 minute and several hours. Our results indicate a steepening of the PSD slope for timescales shorter than 0.3 hr. The spectral energy distribution is flat at 220 GHz, and there are no time lags between the 213 and 229 GHz frequency bands, suggesting low optical depth for the event horizon scale source. We characterize Sgr A*'s variability, highlighting the different behavior observed just after the X-ray flare, and use Gaussian process modeling to extract a decorrelation timescale and a PSD slope. We also investigate the systematic calibration uncertainties by analyzing data from independent data reduction pipelines.
02921nas a2200457 4500000000100000000000100001008004100002100001900043700002100062700002300083700001700106700002200123700001800145700002300163700001700186700001800203700001500221700002300236700001900259700001600278700002200294700001600316700002600332700002300358700001700381700002100398700001600419700002100435700001400456700001600470700002300486700001900509700001700528700002000545700002400565700004600589245010800635300000900743490000800752520170300760 2022 d 1 aBoris Georgiev 1 aDominic W. Pesce 1 aAvery E. Broderick 1 aVedant Dhruv 1 aCharles F. Gammie 1 aChi-Kwan Chan 1 aKoushik Chatterjee 1 aRazieh Emami 1 aYosuke Mizuno 1 aRoman Gold 1 aChristian M. Fromm 1 aAngelo Ricarte 1 aDoosoo Yoon 1 aAbhishek V. Joshi 1 aBen Prather 1 aAlejandro Cruz-Osorio 1 aMichael D. Johnson 1 aOliver Porth 1 aHéctor Olivares 1 aZiri Younsi 1 aLuciano Rezzolla 1 aJesse Vos 1 aRichard Qiu 1 aAntonios Nathanail 1 aRamesh Narayan 1 aAndrew Chael 1 aRichard Anantua 1 aMonika Moscibrodzka 1 aThe Event Horizon Telescope Collaboration 00 aA Universal Power-law Prescription for Variability from Synthetic Images of Black Hole Accretion Flows a1-32 0 v930 3 aWe present a framework for characterizing the spatiotemporal power spectrum of the variability expected from the horizon-scale emission structure around supermassive black holes, and we apply this framework to a library of general relativistic magnetohydrodynamic (GRMHD) simulations and associated general relativistic ray-traced images relevant for Event Horizon Telescope (EHT) observations of Sgr A*. We find that the variability power spectrum is generically a red-noise process in both the temporal and spatial dimensions, with the peak in power occurring on the longest timescales and largest spatial scales. When both the time-averaged source structure and the spatially integrated light-curve variability are removed, the residual power spectrum exhibits a universal broken power-law behavior. On small spatial frequencies, the residual power spectrum rises as the square of the spatial frequency and is proportional to the variance in the centroid of emission. Beyond some peak in variability power, the residual power spectrum falls as that of the time-averaged source structure, which is similar across simulations; this behavior can be naturally explained if the variability arises from a multiplicative random field that has a steeper high-frequency power-law index than that of the time-averaged source structure. We briefly explore the ability of power spectral variability studies to constrain physical parameters relevant for the GRMHD simulations, which can be scaled to provide predictions for black holes in a range of systems in the optically thin regime. We present specific expectations for the behavior of the M87* and Sgr A* accretion flows as observed by the EHT.
02401nas a2200205 4500000000100000000000100001008004100002100002300043700001500066700001900081700002100100700001500121700001700136700002000153700004600173245012600219300000900345490000800354520183300362 2022 d 1 aAvery E. Broderick 1 aRoman Gold 1 aBoris Georgiev 1 aDominic W. Pesce 1 aPaul Tiede 1 aChunchong Ni 1 aKotaro Moriyama 1 aThe Event Horizon Telescope Collaboration 00 aCharacterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI a1-30 0 v930 3 aThe extraordinary physical resolution afforded by the Event Horizon Telescope has opened a window onto the astrophysical phenomena unfolding on horizon scales in two known black holes, M87* and Sgr A*. However, with this leap in resolution has come a new set of practical complications. Sgr A* exhibits intraday variability that violates the assumptions underlying Earth aperture synthesis, limiting traditional image reconstruction methods to short timescales and data sets with very sparse (u, v) coverage. We present a new set of tools to detect and mitigate this variability. We develop a data-driven, model-agnostic procedure to detect and characterize the spatial structure of intraday variability. This method is calibrated against a large set of mock data sets, producing an empirical estimator of the spatial power spectrum of the brightness fluctuations. We present a novel Bayesian noise modeling algorithm that simultaneously reconstructs an average image and statistical measure of the fluctuations about it using a parameterized form for the excess variance in the complex visibilities not otherwise explained by the statistical errors. These methods are validated using a variety of simulated data, including general relativistic magnetohydrodynamic simulations appropriate for Sgr A* and M87*. We find that the reconstructed source structure and variability are robust to changes in the underlying image model. We apply these methods to the 2017 EHT observations of M87*, finding evidence for variability across the EHT observing campaign. The variability mitigation strategies presented are widely applicable to very long baseline interferometry observations of variable sources generally, for which they provide a data-informed averaging procedure and natural characterization of inter-epoch image consistency. 02083nas a2200121 4500000000100000000000100001008004100002100004600043245013400089856004500223490000800268520168500276 2022 d 1 aThe Event Horizon Telescope Collaboration 00 aFirst Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way uhttps://doi.org/10.3847/2041-8213/ac6674 0 v930 3 aWe present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), the Galactic center source associated with a supermassive black hole. These observations were conducted in 2017 using a global interferometric array of eight telescopes operating at a wavelength of λ = 1.3 mm. The EHT data resolve a compact emission region with intrahour variability. A variety of imaging and modeling analyses all support an image that is dominated by a bright, thick ring with a diameter of 51.8 ± 2.3 μas (68% credible interval). The ring has modest azimuthal brightness asymmetry and a comparatively dim interior. Using a large suite of numerical simulations, we demonstrate that the EHT images of Sgr A* are consistent with the expected appearance of a Kerr black hole with mass ~4 × 106 M⊙, which is inferred to exist at this location based on previous infrared observations of individual stellar orbits, as well as maser proper-motion studies. Our model comparisons disfavor scenarios where the black hole is viewed at high inclination (i > 50°), as well as nonspinning black holes and those with retrograde accretion disks. Our results provide direct evidence for the presence of a supermassive black hole at the center of the Milky Way, and for the first time we connect the predictions from dynamical measurements of stellar orbits on scales of 103-105 gravitational radii to event-horizon-scale images and variability. Furthermore, a comparison with the EHT results for the supermassive black hole M87* shows consistency with the predictions of general relativity spanning over three orders of magnitude in central mass.
02025nas a2200109 4500000000100000000000100001008004100002100004600043245013400089490000800223520168400231 2022 d 1 aThe Event Horizon Telescope Collaboration 00 aFirst Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration 0 v930 3 aWe present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of ~50 μas, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
01875nas a2200121 4500000000100000000000100001008004100002100004600043245011900089856004500208490000800253520149200261 2022 d 1 aThe Event Horizon Telescope Collaboration 00 aFirst Sagittarius A* Event Horizon Telescope Results. III. Imaging of the Galactic Center Supermassive Black Hole uhttps://doi.org/10.3847/2041-8213/ac6429 0 v930 3 aWe present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr A* has been conducted through surveys over a wide range of imaging assumptions using the classical CLEAN algorithm, regularized maximum likelihood methods, and a Bayesian posterior sampling method. Different prescriptions have been used to account for scattering effects by the interstellar medium toward the Galactic center. Mitigation of the rapid intraday variability that characterizes Sgr A* has been carried out through the addition of a "variability noise budget" in the observed visibilities, facilitating the reconstruction of static full-track images. Our static reconstructions of Sgr A* can be clustered into four representative morphologies that correspond to ring images with three different azimuthal brightness distributions and a small cluster that contains diverse nonring morphologies. Based on our extensive analysis of the effects of sparse (u, v)-coverage, source variability, and interstellar scattering, as well as studies of simulated visibility data, we conclude that the Event Horizon Telescope Sgr A* data show compelling evidence for an image that is dominated by a bright ring of emission with a ring diameter of ~50 μas, consistent with the expected "shadow" of a 4 × 106 M ⊙ black hole in the Galactic center located at a distance of 8 kpc.
02019nas a2200109 4500000000100000000000100001008004100002100004600043245010700089490000800196520170500204 2022 d 1 aThe Event Horizon Telescope Collaboration 00 aFirst Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass 0 v930 3 aIn this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. We find that the Sgr A* data exhibit variability that exceeds what can be explained by the uncertainties in the data or by the effects of interstellar scattering. The magnitude of this variability can be a substantial fraction of the correlated flux density, reaching ~100% on some baselines. Through an exploration of simple geometric source models, we demonstrate that ring-like morphologies provide better fits to the Sgr A* data than do other morphologies with comparable complexity. We develop two strategies for fitting static geometric ring models to the time-variable Sgr A* data; one strategy fits models to short segments of data over which the source is static and averages these independent fits, while the other fits models to the full data set using a parametric model for the structural variability power spectrum around the average source structure. Both geometric modeling and image-domain feature extraction techniques determine the ring diameter to be 51.8 ± 2.3 μas (68% credible intervals), with the ring thickness constrained to have an FWHM between ~30% and 50% of the ring diameter. To bring the diameter measurements to a common physical scale, we calibrate them using synthetic data generated from GRMHD simulations. This calibration constrains the angular size of the gravitational radius to be ${4.8}_{-0.7}^{+1.4}$ μas, which we combine with an independent distance measurement from maser parallaxes to determine the mass of Sgr A* to be ${4.0}_{-0.6}^{+1.1}\times {10}^{6}$ M ⊙.
02036nas a2200109 4500000000100000000000100001008004100002100004600043245012400089490000800213520170500221 2022 d 1 aThe Event Horizon Telescope Collaboration 00 aFirst Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole 0 v930 3 aIn this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 μm, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i ≤ 30°. They have accretion rate (5.2-9.5) × 10-9 M ⊙ yr-1, bolometric luminosity (6.8-9.2) × 1035 erg s-1, and outflow power (1.3-4.8) × 1038 erg s-1. We also find that all models with i ≥ 70° fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 μm flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.
01886nas a2200109 4500000000100000000000100001008004100002100004600043245009300089490000800182520158600190 2022 d 1 aThe Event Horizon Telescope Collaboration 00 aFirst Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric 0 v930 3 aAstrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies Einstein's equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017 EHT observations of Sagittarius A* (Sgr A*). We calibrate the relationship between the geometrically defined black hole shadow and the observed size of the ring-like images using a library that includes both Kerr and non-Kerr simulations. We use the exquisite prior constraints on the mass-to-distance ratio for Sgr A* to show that the observed image size is within ~10% of the Kerr predictions. We use these bounds to constrain metrics that are parametrically different from Kerr, as well as the charges of several known spacetimes. To consider alternatives to the presence of an event horizon, we explore the possibility that Sgr A* is a compact object with a surface that either absorbs and thermally reemits incident radiation or partially reflects it. Using the observed image size and the broadband spectrum of Sgr A*, we conclude that a thermal surface can be ruled out and a fully reflective one is unlikely. We compare our results to the broader landscape of gravitational tests. Together with the bounds found for stellar-mass black holes and the M87 black hole, our observations provide further support that the external spacetimes of all black holes are described by the Kerr metric, independent of their mass.
01721nas a2200157 4500000000100000000000100001008004100002100002300043700001700066700002300083245012100106856004300227300001400270490000800284520127100292 2022 d 1 aAntonios Nathanail 1 aPrasun Dhang 1 aChristian M. Fromm 00 aMagnetic field structure in the vicinity of a supermassive black hole in low-luminosity galaxies: the case of Sgr A* uhttps://doi.org/10.1093/mnras/stac1276 a5204-5210 0 v513 3 aObservations of SgrA∗ have provided a lot of insight on low-luminosity accretion, with a handful of bright flares accompanied with orbital motion close to the horizon. It has been proposed that gas supply comes from stellar winds in the neighborhood of the supermassive black hole. We here argue that the flow at the vicinity of the black hole has a low magnetization and a structure of alternating polarity, totally dictated by the well-studied and long-ago proposed MRI turbulent process. This can be the case, provided that in larger distances from the black hole magnetic diffusivity is dominant, and thus, the magnetic field will never reach equipartition values. For SgrA∗, we show the immediate consequences of this specific magnetic field geometry, which are: (i) an intermittent flow that passes from quiescent states to flaring activity, (ii) no quasi-steady-state jet, (iii) no possibility of a magnetically arrested configuration. Moreover, a further distinctive feature of this geometry is the intense magnetic reconnection events, occurring as layers of opposite magnetic polarity, accreted in the vicinity of the black hole. Finally, we argue that the absence of a jet structure in such case will be a smoking gun in 43 and 86 GHz observations. 02408nas a2200253 4500000000100000000000100001008004100002100002300043700002600066700001800092700002300110700001600133700001700149700002000166700001900186700001700205700001900222700002100241245008600262856004800348300000900396490000800405520174100413 2022 d 1 aChristian M. Fromm 1 aAlejandro Cruz-Osorio 1 aYosuke Mizuno 1 aAntonios Nathanail 1 aZiri Younsi 1 aOliver Porth 1 aHector Olivares 1 aJordy Davelaar 1 aHeino Falcke 1 aMichael Kramer 1 aLuciano Rezzolla 00 aImpact of non-thermal particles on the spectral and structural properties of M87 uhttps://doi.org/10.1051/0004-6361/202142295 a1-22 0 v660 3 aContext. The recent 230 GHz observations of the Event Horizon Telescope are able to image the innermost structure of M 87 and show a ring-like structure that agrees with thermal synchrotron emission generated in a torus surrounding a supermassive black hole. However, at lower frequencies, M 87 is characterised by a large-scale and edge-brightened jet with clear signatures of non-thermal emission. In order to bridge the gap between these scales and to provide a theoretical interpretation of these observations, we perform general relativistic magnetohydrodynamic simulations of accretion onto black holes and jet launching.The direct detection of a bright, ring-like structure in horizon-resolving images of M87* by the Event Horizon Telescope (EHT) is a striking validation of general relativity. The angular size and shape of the ring is a degenerate measure of the location of the emission region, mass, and spin of the black hole. However, we show that the observation of multiple rings, corresponding to the low-order photon rings, can break this degeneracy and produce mass and spin measurements independent of the shape of the rings. We describe two potential experiments that would measure the spin. In the first, observations of the direct emission and n = 1 photon ring are made at multiple epochs with different emission locations. This method is conceptually similar to spacetime constraints that arise from variable structures (or hot spots) in that it breaks the near-perfect degeneracy between emission location, mass, and spin for polar observers using temporal variability. In the second, observations of the direct emission and n = 1 and n = 2 photon rings are made during a single epoch. For both schemes, additional observations comprise a test of general relativity. Thus, comparisons of EHT observations in 2017 and 2018 may be capable of producing the first horizon-scale spin estimates of M87* inferred from strong lensing alone. Additional observation campaigns from future high-frequency, Earth-sized, and space-based radio interferometers can produce high-precision tests of general relativity.
00458nas a2200145 4500000000100000000000100001008004100002100002600043700002100069700004200090245009200132856007000224300001000294490000800304 2021 d 1 aPrashant Kocherlakota 1 aLuciano Rezzolla 1 aEvent Horizon Telescope Collaboration 00 aConstraints on non-Einsteinian black-hole charges with the 2019 EHT observations of M87 uhttps://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.104047 a40-47 0 v103 00350nas a2200121 4500000000100000000000100001008004100002100002900043245007700072856006400149300000700213490000800220 2021 d 1 aet EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. VII. Polarization of the Ring uhttps://iopscience.iop.org/article/10.3847/2041-8213/abe71d a48 0 v910 00374nas a2200121 4500000000100000000000100001008004100002100002900043245010100072856006400173300000700237490000800244 2021 d 1 aet EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon uhttps://iopscience.iop.org/article/10.3847/2041-8213/abe4de a43 0 v910 00337nas a2200121 4500000000100000000000100001008004100002100002000043245007300063856006400136300000700200490000800207 2021 d 1 aet C. Goddi al. 00 aPolarimetric Properties of Event Horizon Telescope Targets from ALMA uhttps://iopscience.iop.org/article/10.3847/2041-8213/abee6a a54 0 v910 02057nas a2200133 4500000000100000000000100001008004100002100002400043245009800067856006400165300000800229490000800237520167800245 2021 d 1 aet J. C. Algaba al. 00 aBroadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign uhttps://iopscience.iop.org/article/10.3847/2041-8213/abef71 aL11 0 v911 3 aIn 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109M⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded. 02426nas a2200181 4500000000100000000000100001008004100002100002000043700001700063700002000080700001600100700002600116245009300142856004700235300001400282490000600296520194200302 2021 d 1 aMichael Janssen 1 aHeino Falcke 1 aMatthias Kadler 1 aEduardo Ros 1 athe EHT Collaboration 00 aEvent Horizon Telescope observations of the jet launching and collimation in Centaurus A uhttps://doi.org/10.1038/s41550-021-01417-w a1017-1028 0 v5 3 aVery-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimetre wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to 10–100 gravitational radii (rg ≡ GM/c2) scales in nearby sources. Centaurus A is the closest radio-loud source to Earth. It bridges the gap in mass and accretion rate between the supermassive black holes (SMBHs) in Messier 87 and our Galactic Centre. A large southern declination of −43° has, however, prevented VLBI imaging of Centaurus A below a wavelength of 1 cm thus far. Here we show the millimetre VLBI image of the source, which we obtained with the Event Horizon Telescope at 228 GHz. Compared with previous observations, we image the jet of Centaurus A at a tenfold higher frequency and sixteen times sharper resolution and thereby probe sub-lightday structures. We reveal a highly collimated, asymmetrically edge-brightened jet as well as the fainter counterjet. We find that the source structure of Centaurus A resembles the jet in Messier 87 on ~500 rg scales remarkably well. Furthermore, we identify the location of Centaurus A’s SMBH with respect to its resolved jet core at a wavelength of 1.3 mm and conclude that the source’s event horizon shadow4 should be visible at terahertz frequencies. This location further supports the universal scale invariance of black holes over a wide range of masses. 02183nas a2200169 4500000000100000000000100001008004100002100001700043700002000060700002000080700001700100245010700117856004500224300001400269490000800283520172200291 2021 d 1 aRazieh Emami 1 aRichard Anantua 1 aAndrew A. Chael 1 aAbraham Loeb 00 aPositron Effects on Polarized Images and Spectra from Jet and Accretion Flow Models of M87* and Sgr A* uhttps://doi.org/10.3847/1538-4357/ac2950 a272, 1-27 0 v923 3 aWe study the effects of including a nonzero positron-to-electron fraction in emitting plasma on the polarized spectral energy distributions and submillimeter images of jet and accretion flow models for near-horizon emission from M87* and Sgr A*. For M87*, we consider a semi-analytic fit to the force-free plasma regions of a general relativistic magnetohydrodynamic jet simulation, which we populate with power-law leptons with a constant electron-to-magnetic pressure ratio. For Sgr A*, we consider a standard self-similar radiatively inefficient accretion flow where the emission is predominantly from thermal leptons with a small fraction in a power-law tail. In both models, we fix the positron-to-electron ratio throughout the emission region. We generate polarized images and spectra from our models using the general relativistic ray tracing and radiative transfer from GRTRANS. We find that a substantial positron fraction reduces the circular polarization fraction at IR and higher frequencies. However, in submillimeter images, higher positron fractions increase polarization fractions due to strong effects of Faraday conversion. We find an M87* jet model that best matches the available broadband total intensity, and 230 GHz polarization data is a sub-equipartition, with positron fraction of ≃10%. We show that jet models with significant positron fractions do not satisfy the polarimetric constraints at 230 GHz from the Event Horizon Telescope (EHT). Sgr A* models show similar trends in their polarization fractions with increasing pair fraction. Both models suggest that resolved, polarized EHT images are useful to constrain the presence of pairs at 230 GHz emitting regions of M87* and Sgr A*. 01725nas a2200133 4500000000100000000000100001008004100002100001900043245009100062856004800153300001100201490000800212520137100220 2021 d 1 aMaciek Wielgus 00 aPhoton rings of spherically symmetric black holes and robust tests of non-Kerr metrics uhttps://doi.org/10.1103/PhysRevD.104.124058 a124058 0 v104 3 aUnder very general assumptions on the accretion flow geometry, images of a black hole illuminated by electromagnetic radiation display a sequence of photon rings (demagnified and rotated copies of the direct image) which asymptotically approach a purely theoretical critical curve—the outline of the black hole photon shell. To a distant observer, these images appear dominated by the direct emission, which forms a ring whose diameter is primarily determined by the effective radius of the emitting region. For that reason, connecting the image diameter seen by a distant observer to the properties of the underlying spacetime crucially relies on a calibration that necessarily depends on the assumed astrophysical source model. On the other hand, the diameter of the photon rings depends more on the detailed geometry of the spacetime than on the source structure. As such, a photon ring detection would allow for the spacetime metric to be probed in a less model-dependent way, enabling more robust tests of general relativity and the Kerr hypothesis. Here we present the photon ring structure of several spherically symmetric black hole spacetimes and perform comparisons with the Schwarzschild/Kerr case. We offer our perspective on future tests of the spacetime metric with photon rings, discussing the challenges and opportunities involved.
3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3 mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable γ-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array (ALMA), at an angular resolution of ∼20 μas (at a redshift of z = 0.536 this corresponds to ∼0.13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M☉). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation. We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across different imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet. We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1.3 and ∼1.7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3 mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≲1010 K, a magnitude or more lower than typical values seen at ≥7 mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
The data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A69 and at http://https://eventhorizontelescope.org/for-astronomers/data 00327nas a2200121 4500000000100000000000100001008004100002100001900043245005900062856006400121300001200185490000800197 2020 d 1 aet R. Gold al. 00 aVerification of Radiative Transfer Schemes for the EHT uhttps://iopscience.iop.org/article/10.3847/1538-4357/ab96c6 aid. 148 0 v897 00350nas a2200121 4500000000100000000000100001008004100002100002400043245007700067856006400144300001200208490000800220 2020 d 1 aet A. Broderick al. 00 aTHEMIS: A Parameter Estimation Framework for the Event Horizon Telescope uhttps://iopscience.iop.org/article/10.3847/1538-4357/ab91a4 aid. 139 0 v897 00409nas a2200121 4500000000100000000000100001008004100002100002200043245012400065856008300189300000700272490000800279 2020 d 1 aet F. Roelofs al. 00 aSYMBA: An end-to-end VLBI synthetic data generation pipeline. Simulating Event Horizon Telescope observations of M 87 uhttps://www.aanda.org/articles/aa/full_html/2020/04/aa36622-19/aa36622-19.html a19 0 v636 00338nas a2200121 4500000000100000000000100001008004100002100002400043245006500067856006900132300000700201490000800208 2020 d 1 aet T. Bronzwaer al. 00 aRAPTOR. II. Polarized radiative transfer in curved spacetime uhttps://ui.adsabs.harvard.edu/abs/2020A%26A...641A.126B/abstract a13 0 v641 00353nas a2200121 4500000000100000000000100001008004100002100002200043245008400065856006700149300000700216490000800223 2020 d 1 aet M. Wielgus al. 00 aMonitoring the Morphology of M87* in 2009-2017 with the Event Horizon Telescope uhttps://ui.adsabs.harvard.edu/abs/2020ApJ...901...67W/abstract a28 0 v901 00344nas a2200121 4500000000100000000000100001008004100002100002200043245007100065856006700136300001300203490000600216 2020 d 1 aet M. Johnson al. 00 aUniversal interferometric signatures of a black hole's photon ring uhttps://ui.adsabs.harvard.edu/abs/2020SciA....6.1310J/abstract aeaaz1310 0 v6 00338nas a2200121 4500000000100000000000100001008004100002100002500043245006500068856006900133300000600202490000800208 2020 d 1 aet E. Kravchenko al. 00 aLinear polarization in the nucleus of M87 at 7 mm and 1.3 cm uhttps://ui.adsabs.harvard.edu/abs/2020A%26A...637L...6K/abstract a9 0 v637 00372nas a2200121 4500000000100000000000100001008004100002100002200043245009900065856006700164300001100231490000800242 2020 d 1 aet D. Psaltis al. 00 aGravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole uhttps://ui.adsabs.harvard.edu/abs/2020PhRvL.125n1104P/abstract a141104 0 v125 00414nas a2200121 4500000000100000000000100001008004100002100002100043245011100064856009500175300001400270490000800284 2020 d 1 aet J. Dexter al. 00 aA parameter survey of Sgr A* radiative models from GRMHD simulations with self-consistent electron heating uhttps://academic.oup.com/mnras/article-abstract/494/3/4168/5817372?redirectedFrom=fulltext a4168-4186 0 v494 00368nas a2200121 4500000000100000000000100001008004100002100003300043245009200076856006400168300000600232490000800238 2019 d 1 aet The EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole uhttps://iopscience.iop.org/article/10.3847/2041-8213/ab0ec7 a1 0 v875 00353nas a2200121 4500000000100000000000100001008004100002100003300043245007700076856006400153300000600217490000800223 2019 d 1 aet The EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. II. Array and Instrumentation uhttps://iopscience.iop.org/article/10.3847/2041-8213/ab0c96 a2 0 v875 00360nas a2200121 4500000000100000000000100001008004100002100003300043245008400076856006400160300000600224490000800230 2019 d 1 aet The EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. III. Data Processing and Calibration uhttps://iopscience.iop.org/article/10.3847/2041-8213/ab0c57 a3 0 v875 00371nas a2200121 4500000000100000000000100001008004100002100003300043245009500076856006400171300000600235490000800241 2019 d 1 aet The EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole uhttps://iopscience.iop.org/article/10.3847/2041-8213/ab0e85 a4 0 v875 00365nas a2200121 4500000000100000000000100001008004100002100003300043245008900076856006400165300000600229490000800235 2019 d 1 aet The EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring uhttps://iopscience.iop.org/article/10.3847/2041-8213/ab0f43 a5 0 v875 00373nas a2200121 4500000000100000000000100001008004100002100003300043245009700076856006400173300000600237490000800243 2019 d 1 aet The EHT Collaboration al. 00 aFirst M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole uhttps://iopscience.iop.org/article/10.3847/2041-8213/ab1141 a6 0 v875 00334nas a2200109 4500000000100000000000100001008004100002100002200043245007400065856007700139490000800216 2019 d 1 aet F. Roelofs al. 00 aSimulations of imaging the event horizon of Sagittarius A* from space uhttps://www.aanda.org/articles/aa/abs/2019/05/aa32423-17/aa32423-17.html 0 v625 00352nas a2200121 4500000000100000000000100001008004100002100002200043245008600065856006400151300000700215490000800222 2019 d 1 aet S. Issaoun al. 00 aThe Size, Shape, and Scattering of Sagittarius A* at 86 GHz: First VLBI with ALMA uhttps://iopscience.iop.org/article/10.3847/1538-4357/aaf732 a30 0 v871 00398nas a2200121 4500000000100000000000100001008004100002100001800043245013700061856006400198300000600262490000800268 2019 d 1 aet Z. Zhu al. 00 aTesting General Relativity with the Black Hole Shadow Size and Asymmetry of Sagittarius A*: Limitations from Interstellar Scattering uhttps://iopscience.iop.org/article/10.3847/1538-4357/aaef3d a6 0 v870 00306nas a2200109 4500000000100000000000100001008004100002100002400043245005700067856006400124490000800188 2019 d 1 aet L. Blackburn al. 00 aEHT-HOPS pipeline for millimeter VLBI data reduction uhttps://iopscience.iop.org/article/10.3847/1538-4357/ab328d 0 v882 00394nas a2200109 4500000000100000000000100001008004100002100002200043245013400065856007700199490000800276 2019 d 1 aet M. Janssen al. 00 arPICARD: A CASA-based Calibration Pipeline for VLBI Data. Calibration and imaging of 7 mm VLBA observations of the AGN jet in M87 uhttps://www.aanda.org/articles/aa/abs/2019/06/aa35181-19/aa35181-19.html 0 v626 00359nas a2200121 4500000000100000000000100001008004100002100002000043245009100063856006400154300001100218490000800229 2019 d 1 aet C. Goddi al. 00 aCalibration of ALMA as a phased array: ALMA observations during the 2017 VLBI campaign uhttps://iopscience.iop.org/article/10.1088/1538-3873/ab136a a075003 0 v131 00332nas a2200109 4500000000100000000000100001008004100002100002000043245008700063856006400150490000800214 2019 d 1 aet O. Porth al. 00 aThe Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project uhttps://iopscience.iop.org/article/10.3847/1538-4365/ab29fd 0 v243 00344nas a2200109 4500000000100000000000100001008004100002100002600043245010700069856005100176490000700227 2019 d 1 aet L. Christensen al. 00 aAn Unprecedented Global Communications Campaign for the Event Horizon Telescope First Black Hole Image uhttps://www.capjournal.org/issues/26/26_11.pdf 0 v26 00368nas a2200121 4500000000100000000000100001008004100002100002000043245006700063856009800130300001000228490000800238 2019 d 1 aet C. Goddi al. 00 aFirst M87 Event Horizon Telescope Results and the Role of ALMA uhttps://www.eso.org/sci/publications/messenger/archive/no.177-sep19/messenger-no177-25-35.pdf a25-35 0 v177 00438nas a2200181 4500000000100000000000100001008004100002100001400043700001400057700001600071700001300087700002000100700001600120700001400136700001400150700001600164245007600180 2018 d 1 aY. Mizuno 1 aZ. Younsi 1 aC. M. Fromm 1 aO. Porth 1 aM. De Laurentis 1 aH. Olivares 1 aH. Falcke 1 aM. Kramer 1 aL. Rezzolla 00 aThe current ability to test theories of gravity with black hole shadows 00362nas a2200121 4500000000100000000000100001008004100002100002300043245009600066856006400162300000600226490000800232 2018 d 1 aet L. Medeiros al. 00 aPrincipal Component Analysis as a Tool for Characterizing Black Hole Images and Variability uhttps://iopscience.iop.org/article/10.3847/1538-4357/aad37a a7 0 v864 00394nas a2200121 4500000000100000000000100001008004100002100002000043245011600063856007100179300001400250490000800264 2018 d 1 aet A. Chael al. 00 aThe role of electron heating physics in images and variability of the Galactic Center black hole Sagittarius A* uhttps://academic.oup.com/mnras/article-abstract/478/4/5209/4996793 a5209-5229 0 v478 00333nas a2200133 4500000000100000000000100001008004100002100001600043700002100059700001700080700001400097245008000111490000800191 2018 d 1 aJ. Davelaar 1 aM. Mościbrodzka 1 aT. Bronzwaer 1 aH. Falcke 00 aGeneral relativistic magnetohydrodynamical κ-jet models for Sagittarius A* 0 v612 00409nas a2200169 4500000000100000000000100001008004100002100001600043700001800059700001700077700002000094700001500114700001500129245008000144300000700224490000800231 2018 d 1 aA. A. Chael 1 aM. D. Johnson 1 aK. L. Bouman 1 aL. L. Blackburn 1 aK. Akiyama 1 aR. Narayan 00 aInterferometric Imaging Directly with Closure Phases and Closure Amplitudes a23 0 v857 00298nas a2200121 4500000000100000000000100001008004100002100002100043700001700064245008000081300000700161490000800168 2018 d 1 aM. Mościbrodzka 1 aC. F. Gammie 00 aIPOLE - semi-analytic scheme for relativistic polarized radiative transport a43 0 v457 00296nas a2200109 4500000000100000000000100001008004100002100001900043700001500062245010200077490000700179 2018 d 1 aS. B. Giddings 1 aD. Psaltis 00 aEvent Horizon Telescope Observations as Probes for Quantum Structure of Astrophysical Black Holes 0 v97 00464nas a2200169 4500000000100000000000100001008004100002100001900043700001500062700001900077700001500096700001500111700003000126245011900156300001100275490000800286 2018 d 1 aL. D. Matthews 1 aG. B. Crew 1 aS. S. Doeleman 1 aR. Lacasse 1 aA. F. Saez 1 aALMA Phasing Project Team 00 aThe ALMA Phasing System: A Beamforming Capability for Ultra-high-resolution Science at (Sub)Millimeter Wavelengths a015002 0 v130 00342nas a2200121 4500000000100000000000100001008004100002100001800043245007900061856006400140300000800204490000800212 2018 d 1 aet J. Kim al. 00 aThe 1.4 mm core of Cen A: first VLBI results with the South Pole Telescope uhttps://iopscience.iop.org/article/10.3847/1538-4357/aac7c6 a129 0 v861 00299nas a2200109 4500000000100000000000100001008004100002100001700043245011400060300000700174490000800181 2018 d 1 aet R. Lu al. 00 aDetection of intrinsic source structure at ~3 Schwarzschild radii with Millimeter-VLBI observations of Sgr A* a60 0 v859 00412nas a2200121 4500000000100000000000100001008004100002100002400043245014300067856006400210300000700274490000900281 2018 d 1 aet K. Kuromochi al. 00 aSuperresolution Interferometric Imaging with Sparse Modeling Using Total Squared Variation -- Application to Imaging the Black Hole Shadow uhttps://iopscience.iop.org/article/10.3847/1538-4357/aab6b5 a56 0 v2018 00447nas a2200181 4500000000100000000000100001008004100002100001600043700001500059700001300074700001500087700001100102700001800113700001600131245010300147300000700250490000800257 2018 d 1 aL. Medeiros 1 aC.-K. Chan 1 aF. Özel 1 aD. Psaltis 1 aJ. Kim 1 aD. P. Marrone 1 aA. Sadowski 00 aGRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A* a13 0 v856 00260nas a2200109 4500000000100000000000100001008004100002100002200043245006900065300000700134490000900141 2018 d 1 aet C.-K. Chan al. 00 aGRay2: A General Purpose Geodesic Integrator for Kerr Spacetimes a59 0 v867 00400nas a2200157 4500000000100000000000100001008004100002100001200043700001300055700001500068700001500083700001400098245011400112300000800226490000800234 2018 d 1 aD. Ball 1 aF. Özel 1 aD. Psaltis 1 aC.-K. Chan 1 aL. Sironi 00 aThe Properties of Reconnection Current Sheets in GRMHD Simulations of Radiatively Inefficient Accretion Flows a184 0 v853 00277nas a2200109 4500000000100000000000100001008004100002100001800043245005700061856003900118490001000157 2018 d 1 aet J. Kim al. 00 aA VLBI receiving system for the South Pole Telescope uhttps://doi.org/10.1117/12.2301005 0 v10708 00354nas a2200121 4500000000100000000000100001008004100002100002100043245007500064856007700139300000800216490000800224 2018 d 1 aet J.-Y. Kim al. 00 aThe limb-brightened jet of M87 down to the 7 Schwarzschild radii scale uhttps://www.aanda.org/articles/aa/abs/2018/08/aa32921-18/aa32921-18.html a188 0 v616 00382nas a2200133 4500000000100000000000100001008004100002100002400043700001400067245008300081856006200164300001400226490000800240 2018 d 1 aA. Jiménez-Rosales 1 aJ. Dexter 00 aThe impact of Faraday effects on polarized black hole images of Sagittarius A* uhttps://academic.oup.com/mnras/article/478/2/1875/4995232 a1875-1883 0 v478 00370nas a2200121 4500000000100000000000100001008004100002100002300043245010200066856006400168300000800232490000800240 2018 d 1 aet G. C. Bower al. 00 aALMA Polarimetry of Sgr A*: Probing the Accretion Flow from the Event Horizon to the Bondi Radius uhttps://iopscience.iop.org/article/10.3847/1538-4357/aae983 a101 0 v868 00352nas a2200121 4500000000100000000000100001008004100002100002500043245008200068856006400150300000800214490000800222 2018 d 1 aet M. D. Johnson al. 00 aThe Scattering and Intrinsic Structure of Sagittarius A* at Radio Wavelengths uhttps://iopscience.iop.org/article/10.3847/1538-4357/aadcff a104 0 v865 00380nas a2200121 4500000000100000000000100001008004100002100002000043245011100063856006200174300001400236490000800250 2018 d 1 aet A. Chael al. 00 aTwo-temperature, Magnetically Arrested Disc simulations of the jet from the supermassive black hole in M87 uhttps://academic.oup.com/mnras/article/486/2/2873/5432368 a2873-2895 0 v486 00376nas a2200133 4500000000100000000000100001008004100002100001300043700001700056245008900073856006400162300000800226490000800234 2018 d 1 aH.-Y. Pu 1 aA. Broderick 00 aProbing the Innermost Accretion Flow Geometry of Sgr A* with Event Horizon Telescope uhttps://iopscience.iop.org/article/10.3847/1538-4357/aad086 a148 0 v863 00238nas a2200109 4500000000100000000000100001008004100002100001500043245005500058300000900113490000600122 2017 d 1 aA. Lobanov 00 aBeyond the event horizon or altogether without it? a0069 0 v1 00587nas a2200241 4500000000100000000000100001008004100002100001500043700001300058700001300071700001600084700001400100700001700114700002100131700001400152700002100166700001700187700001300204700002000217245009200237300000800329490000800337 2017 d 1 aK. Akiyama 1 aS. Ikeda 1 aM. Pleau 1 aV. L. Fish 1 aF. Tazaki 1 aK. Kuramochi 1 aA. E. Broderick 1 aJ. Dexter 1 aM. Mościbrodzka 1 aM. Gowanlock 1 aM. Honma 1 aS. S. Doeleman 00 aSuperresolution Full-polarimetric Imaging for Radio Interferometry with Sparse Modeling a159 0 v153 00639nas a2200253 4500000000100000000000100001008004100002100001500043700001700058700001300075700001600088700001400104700001300118700002000131700002100151700001400172700002100186700001800207700001700225700001400242245011500256300000600371490000800377 2017 d 1 aK. Akiyama 1 aK. Kuramochi 1 aS. Ikeda 1 aV. L. Fish 1 aF. Tazaki 1 aM. Honma 1 aS. S. Doeleman 1 aA. E. Broderick 1 aJ. Dexter 1 aM. Mościbrodzka 1 aK. L. Bouman 1 aA. A. Chael 1 aM. Zaizen 00 aImaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope Using Sparse Modeling a1 0 v838 00237nas a2200109 4500000000100000000000100001008004100002100001200043245006000055300000600115490000600121 2017 d 1 aK. Hada 00 aThe Structure and Propagation of the Misaligned Jet M87 a2 0 v5 01247nas a2200541 4500000000100000000000100001008004100002100001200043700001600055700001200071700001500083700001600098700001400114700001200128700001700140700001500157700001400172700001500186700001400201700001400215700002000229700001400249700001100263700001500274700001500289700001600304700001300320700001400333700001000347700001100357700001100368700001700379700001400396700001300410700001500423700001500438700001000453700001400463700001600477700001500493700001400508700001400522700001700536700001900553245011900572300000700691490000700698 2017 d 1 aK. Hada 1 aJ. H. Park 1 aM. Kino 1 aK. Niinuma 1 aB. W. Sohn 1 aH. W. Ro 1 aT. Jung 1 aJ.-C. Algaba 1 aG.-Y. Zhao 1 aS.-S. Lee 1 aK. Akiyama 1 aS. Trippe 1 aK. Wajima 1 aS. Sawada-Satoh 1 aF. Tazaki 1 aI. Cho 1 aJ. Hodgson 1 aJ. A. Lee 1 aY. Hagiwara 1 aM. Honma 1 aS. Koyama 1 aJ. Oh 1 aT. Lee 1 aH. Yoo 1 aN. Kawaguchi 1 aD.-G. Roh 1 aS.-J. Oh 1 aJ.-H. Yeom 1 aD.-K. Jung 1 aC. Oh 1 aH.-R. Kim 1 aJ.-Y. Hwang 1 aD.-Y. Byun 1 aS.-H. Cho 1 aH.-G. Kim 1 aH. Kobayashi 1 aK. M. Shibata 00 aPilot KaVA monitoring on the M87 jet: confirming the inner jet structure and superluminal motions at sub-pc scales a71 0 v69 00329nas a2200145 4500000000100000000000100001008004100002100001600043700002000059700001100079700001700090245006200107300000700169490000700176 2017 d 1 aB. Boccardi 1 aT. P. Kirchbaum 1 aE. Ros 1 aJ. A. Zenzus 00 aRadio observations of active galactic nuclei with mm-VLBI a48 0 v25 00399nas a2200169 4500000000100000000000100001008004100002100001300043700001400056700001400070700001600084700001800100700003100118245006100149300001200210490000700222 2017 d 1 aC. Goddi 1 aH. Falcke 1 aM. Kramer 1 aL. Rezzolla 1 aC. Brinkerink 1 aBlackHoleCam Collaboration 00 aBlackHoleCam: Fundamental physics of the galactic center a1730001 0 v26 00483nas a2200217 4500000000100000000000100001008004100002100001800043700001700061700002000078700001600098700001300114700001600127700001500143700001500158700001500173700001900188245004200207300000800249490000800257 2017 d 1 aM. D. Johnson 1 aK. L. Bouman 1 aL. L. Blackburn 1 aA. A. Chael 1 aJ. Rosen 1 aH. Shiokawa 1 aF. Roelofs 1 aK. Akiyama 1 aV. L. Fish 1 aS. S. Doeleman 00 aDynamical Imaging with Interferometry a172 0 v850 00301nas a2200133 4500000000100000000000100001008004100002100001600043700001700059700001900076245005700095300000700152490000800159 2017 d 1 aH. Shiokawa 1 aC. F. Gammie 1 aS. S. Doeleman 00 aTime Domain Filtering of Resolved Images of Sgr A∗ a29 0 v846 00403nas a2200169 4500000000100000000000100001008004100002100002000043700001400063700001300077700001400090700001300104700001600117700001600133245007600149490000800225 2017 d 1 aM. De Laurentis 1 aZ. Younsi 1 aO. Porth 1 aY. Mizuno 1 aC. Fromm 1 aL. Rezzolla 1 aH. Olivares 00 aObservational signatures of spherically-symmetric black hole spacetimes 0 v942 00213nas a2200097 4500000000100000000000100001008004100002100001400043245005000057490000800107 2017 d 1 aH. Falcke 00 aImaging black holes: past, present and future 0 v942 00418nas a2200157 4500000000100000000000100001008004100002100001500043700001800058700001600076700001900092700001400111245012000125300000700245490000800252 2017 d 1 aF. Roelofs 1 aM. D. Johnson 1 aH. Shiokawa 1 aS. S. Doeleman 1 aH. Falcke 00 aQuantifying Intrinsic Variability of Sagittarius A* Using Closure Phase Measurements of the Event Horizon Telescope a19 0 v847 00398nas a2200145 4500000000100000000000100001008004100002100001200043700001900055700001800074700001900092245012600111300000700237490000800244 2017 d 1 aR. Gold 1 aJ. C. McKinney 1 aM. D. Johnson 1 aS. S. Doeleman 00 aProbing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations a20 0 v837 00211nas a2200109 4500000000100000000000100001008004100002100001900043245002500062300000800087490000600095 2017 d 1 aS. S. Doeleman 00 aSeeing the unseeable a646 0 v1 00403nas a2200157 4500000000100000000000100001008004100002100001700043700001800060700001600078700001600094700001500110700001900125700001800144245008300162 2017 d 1 aK. L. Bouman 1 aM. D. Johnson 1 aA. V. Dalca 1 aA. A. Chael 1 aF. Roelofs 1 aS. S. Doeleman 1 aW. T. Freeman 00 aReconstructing Video from Interferometric Measurements of Time-Varying Sources 00562nas a2200241 4500000000100000000000100001008004100002100001400043700001400057700001600071700001600087700001400103700001900117700001500136700001200151700001800163700001500181700001800196700001500214245007400229300000900303490000800312 2017 d 1 aJ. Dexter 1 aA. Deller 1 aG. C. Bower 1 aP. Demorest 1 aM. Kramer 1 aB. W. Stappers 1 aA. G. Lyne 1 aM. Kerr 1 aL. G. Spitler 1 aD. Psaltis 1 aM. D. Johnson 1 aR. Narayan 00 aLocating the intense interstellar scattering towards the inner Galaxy a3563 0 v471 00315nas a2200133 4500000000100000000000100001008004100002100001600043700001500059700001600074245007400090300000900164490000800173 2017 d 1 aA. A. Chael 1 aR. Narayan 1 aA. Sadowski 00 aEvolving non-thermal electrons in simulations of black hole accretion a2367 0 v470 00440nas a2200181 4500000000100000000000100001008004100002100001600043700001500059700001300074700001500087700001100102700001800113700001600131245009600147300000700243490000800250 2017 d 1 aL. Medeiros 1 aC.-K. Chan 1 aF. Özel 1 aD. Psaltis 1 aJ. Kim 1 aD. P. Marrone 1 aA. Sadowski 00 aVariability in GRMHD Simulations of Sgr A*: Implications for EHT Closure Phase Observations a13 0 v844 00447nas a2200145 4500000000100000000000100001008004100002100002000043700001100063700001400074700001800088245017800106300000900284490000800293 2016 d 1 aI. Martí-Vidal 1 aA. Roy 1 aJ. Conway 1 aA. J. Zensus 00 aCalibration of mixed-polarization interferometric observations. Tools for the reduction of interferometric data from elements with linear and circular polarization receivers aA143 0 v587 02282nas a2200961 4500000000100000000000100001008004100002100001600043700001900059700002000078700002100098700001500119700001300134700001500147700001200162700001800174700001300192700001600205700001700221700001700238700001600255700001700271700001800288700001600306700001700322700001800339700001500357700001600372700001400388700001400402700001600416700001400432700001400446700001500460700001700475700001900492700001800511700001300529700001300542700001700555700001100572700002100583700001200604700002100616700001200637700001500649700001600664700001900680700001700699700002100716700002300737700001300760700001300773700002000786700001400806700002000820700002200840700001700862700001600879700001500895700001600910700001800926700001400944700001500958700001300973700002000986700002301006700001301029700002201042700001401064700002201078700001701100700001301117700001401130700001701144700001301161700001701174700001801191700001801209245007801227300000701305490000801312 2016 d 1 aV. L. Fish 1 aM. D. Johnson 1 aS. S. Doeleman 1 aA. E. Broderick 1 aD. Psaltis 1 aR.-S. Lu 1 aK. Akiyama 1 aW. Alef 1 aJ. C. Algaba 1 aK. Asada 1 aC. Beaudoin 1 aA. Bertarini 1 aL. Blackburn 1 aR. Blundell 1 aG. C. Bower 1 aC. Brinkerink 1 aR. Cappallo 1 aA. A. Chael 1 aR. Chamberlin 1 aC.-K. Chan 1 aG. B. Crew 1 aJ. Dexter 1 aM. Dexter 1 aS. A. Dzib 1 aH. Falcke 1 aR. Freund 1 aP. Friberg 1 aC. H. Greer 1 aM. A. Gurwell 1 aP. T. P. Ho 1 aM. Honma 1 aM. Inoue 1 aT. Johannsen 1 aJ. Kim 1 aT. P. Krichbaum 1 aJ. Lamb 1 aJ. León-Tavares 1 aA. Loeb 1 aL. Loinard 1 aD. MacMahon 1 aD. P. Marrone 1 aJ. M. Moran 1 aM. Mościbrodzka 1 aG. N. Ortiz-León 1 aT. Oyama 1 aF. Özel 1 aR. L. Plambeck 1 aN. Pradel 1 aR. A. Primiani 1 aA. E. E. Rogers 1 aK. Rosenfeld 1 aH. Rottmann 1 aA. L. Roy 1 aC. Ruszczyk 1 aD. L. Smythe 1 aJ. SooHoo 1 aJ. Spilker 1 aJ. Stone 1 aP. Strittmatter 1 aR. P. J. Tilanus 1 aM. Titus 1 aL. Vertatschitsch 1 aJ. Wagner 1 aJ. F. C. Wardle 1 aJ. Weintroub 1 aD. Woody 1 aM. Wright 1 aP. Yamaguchi 1 aA. Young 1 aK. H. Young 1 aJ. A. Zensus 1 aL. M. Ziurys 00 aPersistent Asymmetric Structure of Sagittarius A* on Event Horizon Scales a90 0 v820 00533nas a2200205 4500000000100000000000100001008004100002100002100043700001600064700001900080700001700099700001200116700002000128700001500148700001700163700001500180245011600195300000800311490000800319 2016 d 1 aA. E. Broderick 1 aV. L. Fish 1 aM. D. Johnson 1 aK. Rosenfeld 1 aC. Wang 1 aS. S. Doeleman 1 aK. Akiyama 1 aT. Johannsen 1 aA. L. Roy 00 aModeling Seven Years of Event Horizon Telescope Observations with Radiatively Inefficient Accretion Flow Models a137 0 v820 00352nas a2200157 4500000000100000000000100001008004100002100001300043700001400056700001500070700001200085700001300097245007000110300000700180490000700187 2016 d 1 aS. Ikeda 1 aF. Tazaki 1 aK. Akiyama 1 aK. Hada 1 aM. Honma 00 aPRECL: A new method for interferometry imaging from closure phase a45 0 v68 00399nas a2200169 4500000000100000000000100001008004100002100001500043700001200058700001800070700001300088700001700101700001300118245008200131300000800213490000800221 2016 d 1 aK. Akiyama 1 aStawarz 1 aY. T. Tanaka 1 aH. Nagai 1 aM. Giroletti 1 aM. Honma 00 aEVN Observations of HESS J1943+213: Evidence for an Extreme TeV BL Lac Object aL26 0 v823 00306nas a2200121 4500000000100000000000100001008004100002100001500043700001900058245009200077300000700169490000800176 2016 d 1 aK. Akiyama 1 aM. D. Johnson 00 aInterstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB 150418 aL3 0 v824 00449nas a2200181 4500000000100000000000100001008004100002100001100043700001300054700001200067700001600079700001400095700001700109700001400126245011300140300000700253490000700260 2016 d 1 aA. Doi 1 aT. Oyama 1 aY. Kono 1 aA. Yamauchi 1 aS. Suzuki 1 aN. Matsumoto 1 aF. Tazaki 00 aA radio detection survey of narrow-line Seyfert 1 galaxies using very long baseline interferometry at 22 GHz a73 0 v68 00603nas a2200241 4500000000100000000000100001008004100002100001200043700001200055700001100067700001300078700001300091700001500104700001400119700001200133700001700145700001800162700001500180700001600195245013400211300000800345490000800353 2016 d 1 aK. Hada 1 aM. Kino 1 aA. Doi 1 aH. Nagai 1 aM. Honma 1 aK. Akiyama 1 aF. Tazaki 1 aR. Lico 1 aM. Giroletti 1 aG. Giovannini 1 aM. Orienti 1 aY. Hagiwara 00 aHigh-sensitivity 86 GHz (3.5 mm) VLBI Observations of M87: Deep Imaging of the Jet Base at a Resolution of 10 Schwarzschild Radii a131 0 v817 00407nas a2200169 4500000000100000000000100001008004100002100001600043700001100059700001400070700001200084700001600096700001300112245009900125300000700224490000600231 2016 d 1 aS. Nakahara 1 aA. Doi 1 aY. Murata 1 aK. Hada 1 aM. Nakamura 1 aK. Asada 00 aConical Stream of the Two-Sided Jets in NGC 4261 over the Range of 103-109 Schwarzschild Radii a80 0 v4 00400nas a2200157 4500000000100000000000100001008004100002260001200043100002400055700002300079700001700102700002000119700002400139700002300163245005600186 2016 d c06/2016 1 aKatherine L. Bouman 1 aMichael D. Johnson 1 aDaniel Zoran 1 aVincent L. Fish 1 aSheperd S. Doeleman 1 aWilliam T. Freeman 00 aComputational Imaging for VLBI Image Reconstruction 00304nas a2200121 4500000000100000000000100001008004100002100002100043700001400064700001600078245008000094490000800174 2016 d 1 aM. Mościbrodzka 1 aH. Falcke 1 aH. Shiokawa 00 aGeneral relativistic magnetohydrodynamical simulations of the jet in M 87 0 v568 00337nas a2200133 4500000000100000000000100001008004100002100002100043700002100064700001800085700001400103245007800117490000800195 2016 d 1 aR. Fraga-Encinas 1 aM. Mościbrodzka 1 aC. Brinkerink 1 aH. Falcke 00 aProbing spacetime around Sagittarius A* using modeled VLBI closure phases 0 v588 00277nas a2200109 4500000000100000000000100001008004100002100001800043245009100061300000700152490000800159 2016 d 1 aM. D. Johnson 00 aStochastic Optics: A Scattering Mitigation Framework for Radio Interferometric Imaging a74 0 v833 00672nas a2200265 4500000000100000000000100001008004100002260007500043100001400118700001500132700001700147700001300164700001300177700001400190700002100204700001300225700001800238700002000256700001500276700002400291700001500315700001500330700002500345245003600370 2016 d bSouth African Astronomical Observatory (SAAO) aCape Town, South Africa 1 aM. Backes 1 aC. Müller 1 aJ. E. Conway 1 aR. Deane 1 aR. Evans 1 aH. Falcke 1 aR. Fraga-Encinas 1 aC. Goddi 1 aM. Klein Wolt 1 aT. P. Kirchbaum 1 aG. MacLeod 1 aV. A. R. M. Ribeiro 1 aF. Roelofs 1 aZ.-Q. Shen 1 avan H. J. Langevelde 00 aThe Africa Millimetre Telescope 00255nas a2200121 4500000000100000000000100001008004100002100001800043700001500061245004200076300000700118490000800125 2016 d 1 aM. D. Johnson 1 aR. Narayan 00 aThe Optics of Refractive Substructure a10 0 v826 00514nas a2200217 4500000000100000000000100001008004100002100001700043700002000060700001600080700002000096700001900116700001800135700001500153700001400168700001500182700001800197245006200215300001100277490000800288 2016 d 1 aT. Johannsen 1 aA. E. Broderick 1 aP. M. Plewa 1 aS. Chatzopoulos 1 aS. S. Doeleman 1 aF. Eisenhauer 1 aV. L. Fish 1 aR. Genzel 1 aO. Gerhard 1 aM. D. Johnson 00 aTesting General Relativity with the Shadow Size of Sgr A* a031101 0 v116 00437nas a2200169 4500000000100000000000100001008004100002100001100043700001800054700001500072700001600087700001300103700001500116245012000131300000800251490000800259 2016 d 1 aJ. Kim 1 aD. P. Marrone 1 aC.-K. Chan 1 aL. Medeiros 1 aF. Özel 1 aD. Psaltis 00 aBayesian Techniques for Comparing Time-dependent GRMHD Simulations to Variable Event Horizon Telescope Observations a156 0 v832 00346nas a2200133 4500000000100000000000100001008004100002100001500043700001100058700001400069245011300083300000800196490000800204 2016 d 1 aD. Psaltis 1 aN. Wex 1 aM. Kramer 00 aA Quantitative Test of the No-hair Theorem with Sgr A* Using Stars, Pulsars, and the Event Horizon Telescope a121 0 v818 00391nas a2200145 4500000000100000000000100001008004100002100001500043700001300058700001500071700001800086245012500104300000800229490000800237 2016 d 1 aD. Psaltis 1 aF. Özel 1 aC.-K. Chan 1 aD. P. Marrona 00 aA General Relativistic Null Hypothesis Test with Event Horizon Telescope Observations of the Black Hole Shadow in Sgr A* a115 0 v814 00939nas a2200361 4500000000100000000000100001008004100002100002200043700001500065700001400080700001700094700002100111700001600132700001800148700002000166700002100186700001300207700002500220700001800245700001400263700002100277700001500298700001600313700002100329700002300350700002500373700002300398700001800421700001800439245009800457300001400555490000800569 2016 d 1 aC. D. Brinkerink 1 aC. Müller 1 aH. Falcke 1 aG. C. Bower 1 aT. P. Krichbaum 1 aE. Castillo 1 aA. T. Deller 1 aS. S. Doeleman 1 aR. Fraga-Encinas 1 aC. Goddi 1 aA. Hernández-Gómez 1 aD. H. Hughes 1 aM. Kramer 1 aJ. Léon-Tavares 1 aL. Loinard 1 aA. Montaña 1 aM. Mościbrodzka 1 aG. N. Ortiz-León 1 aD. Sanchez-Arguelles 1 aR. P. J. Tilanus 1 aG. W. Wilson 1 aJ. A. Zensus 00 aAsymmetric structure in Sgr A* at 3 mm from closure phase measurements with VLBA, GBT and LMT a1382-1392 0 v462 00419nas a2200169 4500000000100000000000100001008004100002100001700043700001900060700001500079700002000094700002200114700001800136245008000154300000700234490000800241 2016 d 1 aA. A. Chael 1 aM. D. Johnson 1 aR. Narayan 1 aS. S. Doeleman 1 aJ. F. C. Wardle 1 aK. L. Bouman 00 aHigh-resolution Linear Polarimetric Imaging for the Event Horizon Telescope a11 0 v829 00426nas a2200181 4500000000100000000000100001008004100002100001700043700001200060700002100072700002000093700001600113700001200129700001500141245006900156300001100225490000800236 2016 d 1 aT. Johannsen 1 aC. Wang 1 aA. E. Broderick 1 aS. S. Doeleman 1 aV. L. Fish 1 aA. Loeb 1 aD. Psaltis 00 aTesting General Relativity with Accretion-Flow Imaging of Sgr A* a091101 0 v117 00348nas a2200145 4500000000100000000000100001008004100002260001200043100001800055700001500073700001000088700001600098700001200114245007600126 2016 d c08/2016 1 aL. Benkevitch 1 aK. Akiyama 1 aR. Lu 1 aS. Doeleman 1 aV. Fish 00 aReconstruction of Static Black Hole Images Using Simple Geometric Forms 00571nas a2200217 4500000000100000000000100001008004100002100001600043700001500059700001800074700001700092700001900109700002000128700001700148700002200165700001900187700004600206245008800252300000700340490000600347 2016 d 1 aV. L. Fish 1 aK. Akiyama 1 aK. L. Bouman 1 aA. A. Chael 1 aM. D. Johnson 1 aS. S. Doeleman 1 aL. Blackburn 1 aJ. F. C. Wardle 1 aW. T. Freeman 1 athe Event Horizon Telescope Collaboration 00 aObserving–-and Imaging–-Active Galactic Nuclei with the Event Horizon Telescope a54 0 v4 02273nas a2200949 4500000000100000000000100001008004100002100001600043700001900059700002000078700002100098700001500119700001300134700001500147700001200162700001800174700001300192700001600205700001700221700001700238700001600255700001700271700001800288700001600306700001700322700001800339700001500357700001600372700001400388700001400402700001600416700001400432700001400446700001500460700001700475700001900492700001800511700001300529700001300542700001700555700001100572700002100583700001200604700002000616700001200636700001500648700001600663700001900679700001700698700002000715700002200735700001300757700001200770700002000782700001400802700002000816700002200836700001700858700001600875700001500891700001600906700001800922700001400940700001500954700001300969700002000982700002301002700001301025700002201038700001401060700002201074700001701096700001301113700001401126700001701140700001301157700001701170700001801187700001801205245009201223490000801315 2016 d 1 aV. L. Fish 1 aM. D. Johnson 1 aS. S. Doeleman 1 aA. E. Broderick 1 aD. Psaltis 1 aR.-S. Lu 1 aK. Akiyama 1 aW. Alef 1 aJ. C. Algaba 1 aK. Asada 1 aC. Beaudoin 1 aA. Bertarini 1 aL. Blackburn 1 aR. Blundell 1 aG. C. Bower 1 aC. Brinkerink 1 aR. Cappallo 1 aA. A. Chael 1 aR. Chamberlin 1 aC.-K. Chan 1 aG. B. Crew 1 aJ. Dexter 1 aM. Dexter 1 aS. A. Dzib 1 aH. Falcke 1 aR. Freund 1 aP. Friberg 1 aC. H. Greer 1 aM. A. Gurwell 1 aP. T. P. Ho 1 aM. Honma 1 aM. Inoue 1 aT. Johannsen 1 aJ. Kim 1 aT. P. Krichbaum 1 aJ. Lamb 1 aJ. Leon-Tavares 1 aA. Loeb 1 aL. Loinard 1 aD. MacMahon 1 aD. P. Marrone 1 aJ. M. Moran 1 aM. Moscibrodzka 1 aG. N. Ortiz-Leon 1 aT. Oyama 1 aF. Ozel 1 aR. L. Plambeck 1 aN. Pradel 1 aR. A. Primiani 1 aA. E. E. Rogers 1 aK. Rosenfeld 1 aH. Rottmann 1 aA. L. Roy 1 aC. Ruszczyk 1 aD. L. Smythe 1 aJ. SooHoo 1 aJ. Spilker 1 aJ. Stone 1 aP. Strittmatter 1 aR. P. J. Tilanus 1 aM. Titus 1 aL. Vertatschitsch 1 aJ. Wagner 1 aJ. F. C. Wardle 1 aJ. Weintroub 1 aD. Woody 1 aM. Wright 1 aP. Yamaguchi 1 aA. Young 1 aK. H. Young 1 aJ. A. Zensus 1 aL. M. Ziurys 00 aVizieR Online Data Catalog: 4yr 1.3mm VLBI observations of SgrA* with EHT (Fish+, 2016) 0 v182 00896nas a2200373 4500000000100000000000100001008004100002260001200043100002300055700001900078700002000097700001700117700001600134700001500150700001600165700001600181700001700197700002500214700001800239700002100257700001300278700001600291700001700307700001700324700001600341700002000357700001500377700001600392700001400408700002200422245006300444300000700507490000800514 2016 d c06/2016 1 aG. N. Ortiz-León 1 aM. D. Johnson 1 aS. S. Doeleman 1 aL. Blackburn 1 aV. L. Fish 1 aL. Loinard 1 aM. J. Reid 1 aE. Castillo 1 aA. A. Chael 1 aA. Hernández-Gómez 1 aD. H. Hughes 1 aJ. León-Tavares 1 aR.-S. Lu 1 aA. Montaña 1 aG. Narayanan 1 aK. Rosenfeld 1 aD. Sánchez 1 aF. P. Schloerb 1 aZ.-Q. Shen 1 aH. Shiokawa 1 aJ. SooHoo 1 aL. Vertatschitsch 00 aThe Intrinsic Shape of Sagittarius A* at 3.5 mm Wavelength a40 0 v824 00699nas a2200277 4500000000100000000000100001008004100002100001700043700001400060700001600074700001800090700001400108700002000122700001900142700001900161700001400180700001500194700001500209700001700224700001900241700001600260700001600276245011300292300000800405490000800413 2016 d 1 aG. C. Bower 1 aA. Deller 1 aP. Demorest 1 aA. Brunthaler 1 aH. Falcke 1 aM. Moscibrodzka 1 aR. M. O'Leary 1 aR. P. Eatough 1 aM. Kramer 1 aK. J. Lee 1 aL. Spitler 1 aG. Desvignes 1 aA. P. Rushton 1 aS. Doeleman 1 aM. J. Reid 00 aErratum: "The Proper Motion of the Galactic Center Pulsar Relative to Sagittarius A*" (2015, ApJ, 798, 120)} a133 0 v821 00497nas a2200205 4500000000100000000000100001008004100002100001300043700001500056700001600071700001600087700002000103700001800123700001400141700002100155700001800176245008100194300000800275490000800283 2016 d 1 aR.-S. Lu 1 aF. Roelofs 1 aV. L. Fish 1 aH. Shiokawa 1 aS. S. Doeleman 1 aC. F. Gammie 1 aH. Falcke 1 aT. P. Krichbaum 1 aJ. A. Zensus 00 aImaging an Event Horizon: Mitigation of Source Variability of Sagittarius A* a173 0 v817 00362nas a2200121 4500000000100000000000100001008004100002100001200043700002000055700001900075700002000094245012600114 2016 d 1 aR. Gold 1 aJ. C. McKinney 1 aM. D. Johnson 1 aS. S. Doeleman 00 aProbing the magnetic field structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations 00570nas a2200229 4500000000100000000000100001008004100002100002000043700001500063700001500078700001300093700001200106700001700118700001400135700001200149700001500161700001300176700001900189245011300208300001200321490000700333 2015 d 1 aS. Sawada-Satoh 1 aK. Akiyama 1 aK. Niinuma 1 aH. Nagai 1 aM. Kino 1 aF. D'Ammando 1 aS. Koyama 1 aK. Hada 1 aM. Orienti 1 aM. Honma 1 aK. M. Shibata 00 aApparent Inward Motion of the Parsec-Scale Jet in the BL Lac Object OJ287 during the 2011-2012 γ-ray Flares a429-432 0 v30 00672nas a2200289 4500000000100000000000100001008004100002100001400043700001200057700001100069700001500080700001200095700001300107700001300120700001500133700001700148700001800165700001500183700001300198700001500211700001500226700001700241700001300258245009700271300000700368490000700375 2015 d 1 aS. Koyama 1 aM. Kino 1 aA. Doi 1 aK. Niinuma 1 aK. Hada 1 aH. Nagai 1 aM. Honma 1 aK. Akiyama 1 aM. Giroletti 1 aG. Giovannini 1 aM. Orienti 1 aN. Isobe 1 aJ. Kataoka 1 aD. Paneque 1 aH. Kobayashi 1 aK. Asada 00 aProbing the precise location of the radio core in the TeV blazar Mrk 501 with VERA at 43 GHz a67 0 v67 01636nas a2200673 4500000000100000000000100001008004100002100001500043700001300058700001600071700002000087700002100107700001400128700001200142700001200154700001300166700001300179700001900192700001800211700001300229700001800242700001600260700001700276700001600293700001600309700001400325700001600339700001400355700001500369700001500384700001800399700001300417700002100430700001500451700001600466700001900482700001700501700001600518700001700534700001800551700001600569700001400585700002000599700002200619700001500641700001400656700001800670700002300688700001300711700001400724700001700738700001700755700001700772700001400789700001800803245012500821300000800946490000800954 2015 d 1 aK. Akiyama 1 aR.-S. Lu 1 aV. L. Fish 1 aS. S. Doeleman 1 aA. E. Broderick 1 aJ. Dexter 1 aK. Hada 1 aM. Kino 1 aH. Nagai 1 aM. Honma 1 aM. D. Johnson 1 aJ. C. Algaba 1 aK. Asada 1 aC. Brinkerink 1 aR. Blundell 1 aG. C. Bower 1 aR. Cappallo 1 aG. B. Crew 1 aM. Dexter 1 aS. A. Dzib 1 aR. Freund 1 aP. Friberg 1 aM. Gurwell 1 aP. T. P. Ho 1 aM. Inoue 1 aT. P. Krichbaum 1 aL. Loinard 1 aD. MacMahon 1 aD. P. Marrone 1 aJ. M. Moran 1 aM. Nakamura 1 aN. M. Nagar 1 aG. Ortiz-Leon 1 aR. Plambeck 1 aN. Pradel 1 aR. A. Primiani 1 aA. E. E. Rogers 1 aA. L. Roy 1 aJ. SooHoo 1 aJ.-L. Tavares 1 aR. P. J. Tilanus 1 aM. Titus 1 aJ. Wagner 1 aJ. Weintroub 1 aP. Yamaguchi 1 aK. H. Young 1 aA. Zensus 1 aL. M. Ziurys 00 a230 GHz VLBI Observations of M87: Event-horizon-scale Structure during an Enhanced Very-high-energy γ-Ray State in 2012 a150 0 v807 00404nas a2200169 4500000000100000000000100001008004100002100001500043700001200058700001100070700001200081700001300093700001400106245009800120300000800218490000800226 2015 d 1 aK. Niinuma 1 aM. Kino 1 aA. Doi 1 aK. Hada 1 aH. Nagai 1 aS. Koyama 00 aDiscovery of a Wandering Radio Jet Base after a Large X-Ray Flare in the Blazar Markarian 421 aL14 0 v807 00452nas a2200169 4500000000100000000000100001008004100002100001200043700001600055700001200071700001500083700001300098700001600111245014000127300000700267490000800274 2015 d 1 aM. Kino 1 aF. Takahara 1 aK. Hada 1 aK. Akiyama 1 aH. Nagai 1 aB. W. Sohn 00 aMagnetization Degree at the Jet Base of M87 Derived from the Event Horizon Telescope Data: Testing the Magnetically Driven Jet Paradigm a30 0 v803 00461nas a2200181 4500000000100000000000100001008004100002100001500043700001500058700001300073700001600086700001800102700001600120700001500136245011200151300000800263490000800271 2015 d 1 aC.-K. Chan 1 aD. Psaltis 1 aF. Özel 1 aL. Medeiros 1 aD. P. Marrone 1 aA. Sadowski 1 aR. Narayan 00 aFast Variability and Millimeter/IR Flares in GRMHD Models of Sgr A* from Strong-field Gravitational Lensing a103 0 v812 00404nas a2200157 4500000000100000000000100001008004100002100001500043700001500058700001300073700001500086700001600101245011500117300000600232490000800238 2015 d 1 aC.-K. Chan 1 aD. Psaltis 1 aF. Özel 1 aR. Narayan 1 aA. Sadowski 00 aThe Power of Imaging: Constraining the Plasma Properties of GRMHD Simulations using EHT Observations of Sgr A* a1 0 v799 00452nas a2200169 4500000000100000000000100001008004100002100001500043700001500058700001500073700002000088700001200108700001900120245012800139300000700267490000800274 2015 d 1 aD. Psaltis 1 aR. Narayan 1 aV. L. Fish 1 aA. E. Broderick 1 aA. Loeb 1 aS. S. Doeleman 00 aEvent Horizon Telescope Evidence for Alignment of the Black Hole in the Center of the Milky Way with the Inner Stellar Disk a15 0 v798 01636nas a2200673 4500000000100000000000100001008004100002100001900043700001600062700002000078700001900098700002000117700002200137700001500159700001300174700001600187700001700203700001600220700001700236700001800253700002100271700001600292700001700308700001600325700001400341700001400355700001400369700001500383700001200398700001900410700001800429700001300447700001300460700001600473700002100489700001200510700001200522700001300534700001600547700002000563700001700583700001500600700002000615700001500635700002200650700001700672700001400689700002300703700001300726700002200739700001700761700001400778700001700792700001800809700001800827245009500845300001400940490000800954 2015 d 1 aM. D. Johnson 1 aV. L. Fish 1 aS. S. Doeleman 1 aD. P. Marrone 1 aR. L. Plambeck 1 aJ. F. C. Wardle 1 aK. Akiyama 1 aK. Asada 1 aC. Beaudoin 1 aL. Blackburn 1 aR. Blundell 1 aG. C. Bower 1 aC. Brinkerink 1 aA. E. Broderick 1 aR. Cappallo 1 aA. A. Chael 1 aG. B. Crew 1 aJ. Dexter 1 aM. Dexter 1 aR. Freund 1 aP. Friberg 1 aR. Gold 1 aM. A. Gurwell 1 aP. T. P. Ho 1 aM. Honma 1 aM. Inoue 1 aM. Kosowsky 1 aT. P. Krichbaum 1 aJ. Lamb 1 aA. Loeb 1 aR.-S. Lu 1 aD. MacMahon 1 aJ. C. McKinney 1 aJ. M. Moran 1 aR. Narayan 1 aR. A. Primiani 1 aD. Psaltis 1 aA. E. E. Rogers 1 aK. Rosenfeld 1 aJ. SooHoo 1 aR. P. J. Tilanus 1 aM. Titus 1 aL. Vertatschitsch 1 aJ. Weintroub 1 aM. Wright 1 aK. H. Young 1 aJ. A. Zensus 1 aL. M. Ziurys 00 aResolved magnetic-field structure and variability near the event horizon of Sagittarius A* a1242-1245 0 v350 00519nas a2200217 4500000000100000000000100001008004100002260001200043100002200055700001600077700001300093700001700106700001600123700002100139700001600160700001600176700001700192245007000209300001400279490000800293 2015 d c12/2015 1 aL. Vertatschitsch 1 aR. Primiani 1 aA. Young 1 aJ. Weintroub 1 aG. B. Crew 1 aS. R. McWhirter 1 aC. Beaudoin 1 aS. Doeleman 1 aL. Blackburn 00 aR2DBE: A Wideband Digital Backend for the Event Horizon Telescope a1226-1239 0 v127 00414nas a2200157 4500000000100000000000100001008004100002100001500043700002000058700001600078700002200094700001600116245010500132300001100237490000800248 2015 d 1 aF. Ruesink 1 aH. M. Doeleman 1 aR. Hendrikx 1 aA. F. Koenderink 1 aE. Verhagen 00 aPerturbing Open Cavities: Anomalous Resonance Frequency Shifts in a Hybrid Cavity-Nanoantenna System a203904 0 v115 00443nas a2200169 4500000000100000000000100001008004100002260001200043100001900055700001200074700001600086700001700102700002000119245011800139300000800257490000800265 2015 d c11/2015 1 aM. D. Johnson 1 aA. Loeb 1 aH. Shiokawa 1 aA. A. Chael 1 aS. S. Doeleman 00 aMeasuring the Direction and Angular Velocity of a Black Hole Accretion Disk via Lagged Interferometric Covariance a132 0 v813 01759nas a2200769 4500000000100000000000100001008004100002260001200043100001400055700001500069700002100084700001200105700001400117700001700131700001500148700001400163700001500177700001600192700001400208700001400222700001600236700001500252700001300267700001600280700001800296700001800314700001900332700001700351700001600368700001300384700002900397700001600426700001200442700001500454700001400469700001200483700001700495700001700512700001600529700001700545700001700562700001600579700001200595700001600607700001200623700001300635700001600648700001400664700001300678700001400691700001500705700002000720700001400740700001600754700001600770700001700786700001300803700001400816700001600830700002000846700001500866700001300881700001300894245006600907300000800973490000800981 2015 d c09/2015 1 aJ. Wagner 1 aA. L. Roy 1 aT. P. Krichbaum 1 aW. Alef 1 aA. Bansod 1 aA. Bertarini 1 aR. Güsten 1 aD. Graham 1 aJ. Hodgson 1 aR. Märtens 1 aK. Menten 1 aD. Muders 1 aH. Rottmann 1 aG. Tuccari 1 aA. Weiss 1 aG. Wieching 1 aM. Wunderlich 1 aJ. A. Zensus 1 aJ. P. Araneda 1 aO. Arriagada 1 aM. Cantzler 1 aC. Duran 1 aF. M. Montenegro-Montes 1 aR. Olivares 1 aP. Caro 1 aP. Bergman 1 aJ. Conway 1 aR. Haas 1 aJ. Johansson 1 aM. Lindqvist 1 aH. Olofsson 1 aM. Pantaleev 1 aS. Buttaccio 1 aR. Cappallo 1 aG. Crew 1 aS. Doeleman 1 aV. Fish 1 aR.-S. Lu 1 aC. Ruszczyk 1 aJ. SooHoo 1 aM. Titus 1 aR. Freund 1 aD. Marrone 1 aP. Strittmatter 1 aL. Ziurys 1 aR. Blundell 1 aR. Primiani 1 aJ. Weintroub 1 aK. Young 1 aM. Bremer 1 aS. Sánchez 1 aA. P. Marscher 1 aR. Chilson 1 aK. Asada 1 aM. Inoue 00 aFirst 230 GHz VLBI fringes on 3C 279 using the APEX Telescope aA32 0 v581 00340nas a2200145 4500000000100000000000100001008004100002260001200043100001300055700001600068700001900084245007200103300001200175490000700187 2015 d c08/2015 1 aA. Chael 1 aS. Doeleman 1 aM. D. Johnson 00 aImaging Black Hole Magnetic Fields with the Event Horizon Telescope a2258350 0 v22 00363nas a2200145 4500000000100000000000100001008004100002260001200043100001900055700002000074700004200094245006200136300001200198490000700210 2015 d c08/2015 1 aM. D. Johnson 1 aS. S. Doeleman 1 aEvent Horizon Telescope Collaboration 00 aThe Event Horizon Telescope: New Developments and Results a2257792 0 v22 02154nas a2200961 4500000000100000000000100001008004100002100001500043700001400058700001200072700001600084700001500100700001500115700002000130700001400150700001200164700001200176700001600188700001400204700001400218700001300232700001300245700001300258700001100271700001600282700001400298700001400312700001100326700001500337700001600352700001300368700001300381700001400394700001100408700001500419700001400434700001600448700001300464700001600477700001400493700001400507700001600521700001300537700001200550700001500562700001500577700001500592700001200607700001500619700001400634700001700648700001700665700001500682700001500697700001400712700001100726700001100737700001400748700001100762700001700773700001200790700001600802700001100818700001400829700001500843700001600858700001700874700001600891700001400907700001300921700001500934700001400949700001300963700001900976700001500995700001401010700001301024700001501037700001501052245011001067300000801177490000701185 2014 d 1 aK. Niinuma 1 aS.-S. Lee 1 aM. Kino 1 aB. W. Sohn 1 aK. Akiyama 1 aG.-Y. Zhao 1 aS. Sawada-Satoh 1 aS. Trippe 1 aK. Hada 1 aT. Jung 1 aY. Hagiwara 1 aR. Dodson 1 aS. Koyama 1 aM. Honma 1 aH. Nagai 1 aA. Chung 1 aA. Doi 1 aK. Fujisawa 1 aM.-H. Han 1 aJ.-S. Kim 1 aJ. Lee 1 aJ. A. Lee 1 aA. Miyazaki 1 aT. Oyama 1 aK. Sorai 1 aK. Wajima 1 aJ. Bae 1 aD.-Y. Byun 1 aS.-H. Cho 1 aY. K. Choi 1 aH. Chung 1 aM.-H. Chung 1 aS.-T. Han 1 aT. Hirota 1 aJ.-W. Hwang 1 aD.-H. Je 1 aT. Jike 1 aD.-K. Jung 1 aJ.-S. Jung 1 aJ.-H. Kang 1 aJ. Kang 1 aY.-W. Kang 1 aY. Kan-ya 1 aM. Kanaguchi 1 aN. Kawaguchi 1 aB. G. Kim 1 aH. R. Kim 1 aH.-G. Kim 1 aJ. Kim 1 aJ. Kim 1 aK.-T. Kim 1 aM. Kim 1 aH. Kobayashi 1 aY. Kono 1 aT. Kurayama 1 aC. Lee 1 aJ.-W. Lee 1 aS. H. Lee 1 aY. C. Minh 1 aN. Matsumoto 1 aA. Nakagawa 1 aC. S. Oh 1 aS.-J. Oh 1 aS.-Y. Park 1 aD.-G. Roh 1 aT. Sasao 1 aK. M. Shibata 1 aM.-G. Song 1 aY. Tamura 1 aS.-O. Wi 1 aJ.-H. Yeom 1 aY. J. Yun 00 aVLBI observations of bright AGN jets with the KVN and VERA Array (KaVA): Evaluation of imaging capability a103 0 v66 00335nas a2200145 4500000000100000000000100001008004100002100001300043700001500056700001400071700001300085245007700098300000700175490000700182 2014 d 1 aM. Honma 1 aK. Akiyama 1 aM. Uemura 1 aS. Ikeda 00 aSuper-resolution imaging with radio interferometry using sparse modeling a95 0 v66 00854nas a2200349 4500000000100000000000100001008004100002100001200043700001700055700001200072700001800084700001700102700001800119700001600137700001300153700001100166700001500177700001300192700001500205700001500220700001500235700001900250700001800269700002000287700001400307700001600321700001600337700001900353245011600372300000800488490000800496 2014 d 1 aK. Hada 1 aM. Giroletti 1 aM. Kino 1 aG. Giovannini 1 aF. D'Ammando 1 aC. C. Cheung 1 aM. Beilicke 1 aH. Nagai 1 aA. Doi 1 aK. Akiyama 1 aM. Honma 1 aK. Niinuma 1 aC. Casadio 1 aM. Orienti 1 aH. Krawczynski 1 aJ. L. Gómez 1 aS. Sawada-Satoh 1 aS. Koyama 1 aA. Cesarini 1 aS. Nakahara 1 aM. A. Gurwell 00 aA Strong Radio Brightening at the Jet Base of M 87 during the Elevated Very High Energy Gamma-Ray State in 2012 a165 0 v788 00354nas a2200145 4500000000100000000000100001008004100002100001200043700001600055700001200071700001100083245010000094300000600194490000800200 2014 d 1 aM. Kino 1 aF. Takahara 1 aK. Hada 1 aA. Doi 00 aRelativistic Electrons and Magnetic Fields of the M87 Jet on the \~10 Schwarzschild Radii Scale a5 0 v786 00670nas a2200265 4500000000100000000000100001008004100002100001500043700001300058700001100071700001600082700001800098700001500116700001300131700001600144700001800160700001800178700001300196700001500209700001600224700001400240245013400254300000800388490000800396 2014 d 1 aC. Y. Kuo 1 aK. Asada 1 aR. Rao 1 aM. Nakamura 1 aJ. C. Algaba 1 aH. B. Liu 1 aM. Inoue 1 aP. M. Koch 1 aP. T. P. Ho 1 aS. Matsushita 1 aH.-Y. Pu 1 aK. Akiyama 1 aH. Nishioka 1 aN. Pradel 00 aMeasuring Mass Accretion Rate onto the Supermassive Black Hole in M87 Using Faraday Rotation Measure with the Submillimeter Array aL33 0 v783 00249nas a2200121 4500000000100000000000100001008004100002100001600043700001300059245003600072300001200108490000700120 2014 d 1 aM. J. Reid 1 aM. Honma 00 aMicroarcsecond Radio Astrometry a339-372 0 v52 00359nas a2200145 4500000000100000000000100001008004100002100002000043700001700063700001200080700001500092245009200107300000600199490000800205 2014 d 1 aA. E. Broderick 1 aT. Johannsen 1 aA. Loeb 1 aD. Psaltis 00 aTesting the No-hair Theorem with Event Horizon Telescope Observations of Sagittarius A* a7 0 v784 02069nas a2200133 4500000000100000000000100001008004100002100001600043700001300059245007100072300000800143490000800151520177600159 2013 d 1 aM. Nakamura 1 aK. Asada 00 aThe Parabolic Jet Structure in M87 as a Magnetohydrodynamic Nozzle a118 0 v775 3 aThe structure and dynamics of the M87 jet from sub-milliarcsec to arcsecond scales are continuously examined. We analyzed the Very Long Baseline Array archival data taken at 43 and 86 GHz to measure the size of very long baseline interferometry (VLBI) cores. Millimeter/sub-millimeter VLBI cores are considered as innermost jet emissions, which has been originally suggested by Blandford & Königl. Those components fairly follow an extrapolated parabolic streamline in our previous study so that the jet has a single power-law structure with nearly 5 orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 Schwarzschild radius (r s). We further inspect the jet parabolic structure as a counterpart of the magnetohydrodynamic (MHD) nozzle in order to identify the property of a bulk acceleration. We interpret that the parabolic jet consists of Poynting-flux dominated flows, powered by large-amplitude, nonlinear torsional Alfvén waves. We examine the non-relativistic MHD nozzle equation in a parabolic shape. The nature of trans-fast magnetosonic flow is similar to the one of transonic solution of Parker's hydrodynamic solar wind; the jet becomes super-escape as well as super-fast magnetosonic at around ~103 r s, while the upstream trans-Alfvénic flow speed increases linearly as a function of the distance at ~102-103 r s. We here point out that this is the first evidence to identify these features in astrophysical jets. We propose that the M87 jet is magnetically accelerated, but thermally confined by the stratified interstellar medium inside the sphere of gravitational influence of the SMBH potential, which may be a norm in active galactic nucleus jets. 00481nas a2200205 4500000000100000000000100001008004100002100001200043700001200055700001100067700001300078700001300091700001600104700001700120700001800137700001700155245008800172300000700260490000800267 2013 d 1 aK. Hada 1 aM. Kino 1 aA. Doi 1 aH. Nagai 1 aM. Honma 1 aY. Hagiwara 1 aM. Giroletti 1 aG. Giovannini 1 aN. Kawaguchi 00 aThe Innermost Collimation Structure of the M87 Jet Down to \~10 Schwarzschild Radii a70 0 v775 00482nas a2200181 4500000000100000000000100001008004100002100001200043700001100055700001300066700001300079700001300092700001700105700001800122245014600140300000600286490000800292 2013 d 1 aK. Hada 1 aA. Doi 1 aH. Nagai 1 aM. Inoue 1 aM. Honma 1 aM. Giroletti 1 aG. Giovannini 00 aEvidence for a Nuclear Radio Jet and its Structure down to lsim100 Schwarzschild Radii in the Center of the Sombrero Galaxy (M 104, NGC 4594) a6 0 v779 00380nas a2200157 4500000000100000000000100001008004100002100001500043700001700058700001300075700001300088700001700101245009000118300000700208490000700215 2013 d 1 aK. Akiyama 1 aR. Takahashi 1 aM. Honma 1 aT. Oyama 1 aH. Kobayashi 00 aMulti-Epoch VERA Observations of Sagittarius A*. I. Images and Structural Variability a91 0 v65 00727nas a2200301 4500000000100000000000100001008004100002100001100043700001400054700001700068700001600085700001300101700001900114700001300133700001900146700001300165700001200178700001600190700001600206700001300222700001400235700001300249700001700262700001400279245011800293300000700411490000700418 2013 d 1 aA. Doi 1 aY. Murata 1 aN. Mochizuki 1 aH. Takeuchi 1 aK. Asada 1 aT. J. Hayashi 1 aH. Nagai 1 aK. M. Shibata 1 aT. Oyama 1 aT. Jike 1 aK. Fujisawa 1 aK. Sugiyama 1 aH. Ogawa 1 aK. Kimura 1 aM. Honma 1 aH. Kobayashi 1 aS. Koyama 00 aMultifrequency VLBI Observations of the Broad Absorption Line Quasar J1020+4320: Recently Restarted Jet Activity? a57 0 v65 00612nas a2200265 4500000000100000000000100001008004100002100001300043700001200056700001500068700001500083700001200098700001400110700001500124700001300139700002000152700001300172700001800185700001700203700001500220700001300235245008400248300000700332490000700339 2013 d 1 aH. Nagai 1 aM. Kino 1 aK. Niinuma 1 aK. Akiyama 1 aK. Hada 1 aS. Koyama 1 aM. Orienti 1 aK. Hiura 1 aS. Sawada-Satoh 1 aM. Honma 1 aG. Giovannini 1 aM. Giroletti 1 aK. Shibata 1 aK. Sorai 00 aThe GENJI Programme: Gamma-Ray Emitting Notable AGN Monitoring by Japanese VLBI a24 0 v65 01201nas a2200493 4500000000100000000000100001008004100002100001300043700001600056700001500072700002000087700001800107700001700125700001800142700001800160700001200178700002000190700001400210700001400224700001500238700001900253700001800272700001300290700001300303700001900316700002100335700001500356700001600371700001900387700002000406700001700426700001600443700001400459700001600473700002300489700001300512700001700525700001400542700001700556700001800573245010100591300000700692490000800699 2013 d 1 aR.-S. Lu 1 aV. L. Fish 1 aK. Akiyama 1 aS. S. Doeleman 1 aJ. C. Algaba 1 aG. C. Bower 1 aC. Brinkerink 1 aR. Chamberlin 1 aG. Crew 1 aR. J. Cappallo 1 aM. Dexter 1 aR. Freund 1 aP. Friberg 1 aM. A. Gurwell 1 aP. T. P. Ho 1 aM. Honma 1 aM. Inoue 1 aS. G. Jorstad 1 aT. P. Krichbaum 1 aL. Loinard 1 aD. MacMahon 1 aD. P. Marrone 1 aA. P. Marscher 1 aJ. M. Moran 1 aR. Plambeck 1 aN. Pradel 1 aR. Primiani 1 aR. P. J. Tilanus 1 aM. Titus 1 aJ. Weintroub 1 aM. Wright 1 aK. H. Young 1 aL. M. Ziurys 00 aFine-scale Structure of the Quasar 3C 279 Measured with 1.3 mm Very Long Baseline Interferometry a13 0 v772 00235nas a2200085 4500000000100000000000100001008004100002100002200043245008400065 2013 d 1 aet V. L. Fish al. 00 aHigh-Angular-Resolution and High-Sensitivity Science Enabled by Beamformed ALMA 00324nas a2200133 4500000000100000000000100001008004100002100001500043700001500058700001300073245008900086300000700175490000800182 2013 d 1 aC.-K. Chan 1 aD. Psaltis 1 aF. Özel 00 aGRay: A Massively Parallel GPU-based Code for Ray Tracing in Relativistic Spacetimes a13 0 v777 00489nas a2200205 4500000000100000000000100001008004100002100001200043700001200055700001300067700001100080700001600091700001300107700001700120700001800137700001700155245009600172300000700268490000800275 2012 d 1 aK. Hada 1 aM. Kino 1 aH. Nagai 1 aA. Doi 1 aY. Hagiwara 1 aM. Honma 1 aM. Giroletti 1 aG. Giovannini 1 aN. Kawaguchi 00 aVLBI Observations of the Jet in M 87 during the Very High Energy γ-Ray Flare in 2010 April a52 0 v760 00529nas a2200241 4500000000100000000000100001008004100002100001700043700001200060700001800072700001500090700001600105700001600121700001800137700001100155700001900166700001200185700001500197700001300212245004600225300000800271490000800279 2012 d 1 aM. Giroletti 1 aK. Hada 1 aG. Giovannini 1 aC. Casadio 1 aM. Beilicke 1 aA. Cesarini 1 aC. C. Cheung 1 aA. Doi 1 aH. Krawczynski 1 aM. Kino 1 aN. P. Lee 1 aH. Nagai 00 aThe kinematic of HST-1 in the jet of M 87 aL10 0 v538 00852nas a2200361 4500000000100000000000100001008004100002100001300043700001500056700001700071700001900088700001600107700001400123700001500137700001600152700001300168700001300181700002000194700001800214700001600232700001300248700001600261700001600277700001500293700002100308700001400329700001600343700001700359700001700376245008300393300000600476490000800482 2012 d 1 aR.-S. Lu 1 aV. L. Fish 1 aJ. Weintraub 1 aS. S. Doeleman 1 aG. C. Bower 1 aR. Freund 1 aP. Friberg 1 aP. T. P. Ho 1 aM. Honma 1 aM. Inoue 1 aT. P. Kirchbaum 1 aD. P. Marrone 1 aJ. M. Moran 1 aT. Oyama 1 aR. Plambeck 1 aR. Primiani 1 aZ.-Q. Shen 1 aR. P. J. Tilanus 1 aM. Wright 1 aK. H. Young 1 aL. M. Ziurys 1 aA. J. Zenzus 00 aResolving the Inner Jet Structure of 1924-292 with the Event Horizon Telescope a5 0 v757 00329nas a2200133 4500000000100000000000100001008004100002100001900043700001500062700002500077245007700102300000800179490000800187 2012 d 1 aS. S. Doeleman 1 aV. L. Fish 1 aet D. E. Schenck al. 00 aJet-Launching Structure Resolved Near the Supermassive Black Hole in M87 a355 0 v338 00357nas a2200145 4500000000100000000000100001008004100002100001400043700001300057700001300070700001700083245009600100300000700196490000800203 2012 d 1 aH. Falcke 1 aR. Laing 1 aL. Testi 1 aA. J. Zenzus 00 aReport on the ESO Workshop ''mm-wave VLBI with ALMA and Radio Telescopes around the World'' a50 0 v149 00439nas a2200181 4500000000100000000000100001008004100002100001700043700001500060700001700075700001800092700001300110700001900123700001500142245008500157300000700242490000800249 2012 d 1 aT. Johannsen 1 aD. Psaltis 1 aS. Gillessen 1 aD. P. Marrone 1 aF. Özel 1 aS. S. Doeleman 1 aV. L. Fish 00 aMasses of nearby Supermassive Black Holes with Very Long Baseline Interferometry a30 0 v758 00339nas a2200121 4500000000100000000000100001008004100002100001500043700001700058245012800075300000600203490000800209 2012 d 1 aD. Psaltis 1 aT. Johannsen 00 aA Ray-tracing Algorithm for Spinning Compact Object Spacetimes with Arbitrary Quadrupole Moments. I. Quasi-Kerr Black Holes a1 0 v745 00394nas a2200169 4500000000100000000000100001008004100002100001200043700001100055700001200066700001300078700001600091700001700107245008000124300001200204490000800216 2011 d 1 aK. Hada 1 aA. Doi 1 aM. Kino 1 aH. Nagai 1 aY. Hagiwara 1 aN. Kawaguchi 00 aAn origin of the radio jet in M87 at the location of the central black hole a185-187 0 v477 00326nas a2200121 4500000000100000000000100001008004100002100001500043700002500058245010600083300000700189490000800196 2011 d 1 aV. L. Fish 1 aet S. S. Doleman al. 00 a1.3 mm Wavelength VLBI of Sagittarius A*: Detection of Time-variable Emission on Event Horizon Scales a36 0 v727 00327nas a2200121 4500000000100000000000100001008004100002100001700043700001500060245011500075300000700190490000800197 2011 d 1 aT. Johannsen 1 aD. Psaltis 00 aTesting the No-hair Theorem with Observations in the Electromagnetic Spectrum. III. Quasi-periodic Variability a11 0 v726 00318nas a2200121 4500000000100000000000100001008004100002100001700043700001500060245010500075300000800180490000800188 2010 d 1 aT. Johannsen 1 aD. Psaltis 00 aTesting the No-hair Theorem with Observations in the Electromagnetic Spectrum. II. Black Hole Images a446 0 v718 00336nas a2200121 4500000000100000000000100001008004100002100001700043700001500060245012300075300000800198490000800206 2010 d 1 aT. Johannsen 1 aD. Psaltis 00 aTesting the No-hair Theorem with Observations in the Electromagnetic Spectrum. I. Properties of a Quasi-Kerr Spacetime a187 0 v716 00378nas a2200157 4500000000100000000000100001008004100002100001900043700001500062700002000077700001200097700002000109245007600129300000700205490000800212 2009 d 1 aS. S. Doeleman 1 aV. L. Fish 1 aA. E. Broderick 1 aA. Loeb 1 aA. E. E. Rogers 00 aDetecting Flaring Structures in Sagittarius A* with High-Frequency VLBI a59 0 v695 00311nas a2200121 4500000000100000000000100001008004100002100002000043700001200063245009700075300000900172490000800181 2009 d 1 aA. E. Broderick 1 aA. Loeb 00 aImaging the Black Hole Silhouette of M87: Implications for Jet Formation and Black Hole Spin a1164 0 v697 00292nas a2200109 4500000000100000000000100001008004100002100002600043245009800069300000700167490000800174 2009 d 1 aet S. S. Doeleman al. 00 aEvent-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre a78 0 v455 00226nas a2200085 4500000000100000000000100001008004100002100002600043245007100069 2009 d 1 aet S. S. Doeleman al. 00 aImaging an Event Horizon: submm-VLBI of a Super Massive Black Hole 00445nas a2200181 4500000000100000000000100001008004100002100001500043700001100058700001600069700001500085700001300100700001900113700001300132245010200145300000800247490000800255 2009 d 1 aC.-K. Chan 1 aS. Liu 1 aC. L. Fryer 1 aD. Psaltis 1 aF. Özel 1 aG. Rockefeller 1 aF. Melia 00 aMHD Simulations of Accretion onto Sgr A*: Quiescent Fluctuations, Outbursts, and Quasiperiodicity a512 0 v701 00550nas a2200229 4500000000100000000000100001008004100002100002000043700001700063700001400080700001300094700001500107700001500122700001500137700001800152700002200170700001400192700001700206245008100223300000800304490000800312 1998 d 1 aT. P. Kirchbaum 1 aD. A. Graham 1 aA. Witzel 1 aA. Greve 1 aJ. E. Wink 1 aM. Grewing 1 aF. Colomer 1 ade P. Vicente 1 aJ. Gomez-Gonzalez 1 aA. Baudry 1 aJ. A. Zenzus 00 aVLBI observations of the galactic center source Sgr A* at 86 GHz and 215 GHz a106 0 v335 00529nas a2200229 4500000000100000000000100001008004100002100002000043700001700063700001300080700001500093700001500108700001500123700001800138700001400156700002200170700001500192700001400207245006300221300000700284490000800291 1997 d 1 aT. P. Kirchbaum 1 aD. A. Graham 1 aA. Greve 1 aJ. E. Wink 1 aJ. Alcolea 1 aF. Colomer 1 ade P. Vicente 1 aA. Baudry 1 aJ. Gomez-Gonzalez 1 aM. Grewing 1 aA. Witzel 00 a215 GHz VLBI observations of bright Active Galactic Nuclei a17 0 v323 00721nas a2200289 4500000000100000000000100001008004100002100001300043700001400056700001500070700001500085700001200100700001500112700001400127700001500141700001900156700002200175700002300197700001700220700002000237700001600257700001800273700001400291700001400305245010400319490000800423 1995 d 1 aA. Greve 1 aM. Torres 1 aJ. E. Wink 1 aM. Grewing 1 aW. Wild 1 aJ. Alcolea 1 aA. Barcia 1 aF. Colomer 1 ade P. Vincente 1 aJ. Gomez-Gonzalez 1 aI. Lopez-Fernandez 1 aD. A. Graham 1 aT. P. Kirchbaum 1 aR. Schwartz 1 aK. J. Standke 1 aA. Witzel 1 aA. Baudry 00 a215 GHz VLBI observations: Detection of fringes on the 1147 KM baseline Pico Veleta-Plateau de Bure 0 v299