Event Horizon Telescope observations as probes for quantum structure of astrophysical black holes

Steven B. Giddings and Dimitrios Psaltis
Phys. Rev. D 97, 084035 – Published 19 April 2018

Abstract

The need for a consistent quantum evolution for black holes has led to proposals that their semiclassical description is modified not just near the singularity, but at horizon or larger scales. If such modifications extend beyond the horizon, they influence regions accessible to distant observation. Natural candidates for these modifications behave like metric fluctuations, with characteristic length scales and timescales set by the horizon radius. We investigate the possibility of using the Event Horizon Telescope to observe these effects, if they have a strength sufficient to make quantum evolution consistent with unitarity, without introducing new scales. We find that such quantum fluctuations can introduce a strong time dependence for the shape and size of the shadow that a black hole casts on its surrounding emission. For the black hole in the center of the Milky Way, detecting the rapid time variability of its shadow will require nonimaging timing techniques. However, for the much larger black hole in the center of the M87 galaxy, a variable black-hole shadow, if present with these parameters, would be readily observable in the individual snapshots that will be obtained by the Event Horizon Telescope.

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  • Received 3 July 2016

DOI:https://doi.org/10.1103/PhysRevD.97.084035

© 2018 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
  1. Physical Systems
Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Steven B. Giddings1 and Dimitrios Psaltis2

  • 1Department of Physics, University of California, Santa Barbara, California 93106, USA
  • 2Departments of Astronomy and Physics, University of Arizona, Tucson, Arizona 85721, USA

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Issue

Vol. 97, Iss. 8 — 15 April 2018

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