204 citations · 1.8k across the 55 of their papers we have counts for
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Fundamental Physics Opportunities with the Next-Generation Event Horizon Telescope
Dimitry Ayzenberg, Lindy Blackburn, Richard Brito +45
The Event Horizon Telescope (EHT) Collaboration recently published the first images of the supermassive black holes in the cores of the Messier 87 and Milky Way galaxies. These obs…
Tests of General Relativity using black hole X-ray data
Dimitry Ayzenberg, Cosimo Bambi
The theory of General Relativity has successfully passed a large number of observational tests. The theory has been extensively tested in the weak-field regime with experiments in…
A reflection model with a radial disk density profile
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi +2
In this paper we present RELXILLDGRAD_NK, a relativistic reflection model in which the electron density of the accretion disk is allowed to have a radial power-law profile. The ion…
Constraining the Konoplya-Rezzolla-Zhidenko deformation parameters II: limits from stellar-mass black hole X-ray data
Zhibo Yu, Qunfeng Jiang, Askar B. Abdikamalov +5
Astrophysical black holes are thought to be the Kerr black holes predicted by general relativity, but macroscopic deviations from the Kerr solution can be expected from a number of…
Testing the Kerr black hole hypothesis with the continuum-fitting and the iron line methods: the case of GRS 1915+105
Ashutosh Tripathi, Askar B. Abdikamalov, Dimitry Ayzenberg +4
The continuum-fitting and the iron line methods are currently the two leading techniques for probing the strong gravity region around accreting black holes. In the present work, we…
Testing the Kerr black hole hypothesis with GRS 1716-249 by combining the continuum-fitting and the iron-line methods
Zuobin Zhang, Honghui Liu, Askar B. Abdikamalov +3
The continuum-fitting and the iron-line methods are currently the two leading techniques for measuring the spins of accreting black holes. In the past few years, these two methods…
Constraining the KRZ deformation parameters I: limits from supermassive black hole X-ray data
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi +2
X-ray reflection spectroscopy is a powerful technique for probing the nature of gravity around black holes in the so-called strong field regime. One of the most popular of such pro…
Testing the Weak Equivalence Principle near black holes
Rittick Roy, Askar B. Abdikamalov, Dimitry Ayzenberg +3
Today we have quite stringent constraints on possible violations of the Weak Equivalence Principle from the comparison of the acceleration of test-bodies of different composition i…
Constraints on Einstein-Maxwell dilaton-axion gravity from X-ray reflection spectroscopy
Ashutosh Tripathi, Biao Zhou, Askar B. Abdikamalov +2
Einstein-Maxwell dilaton-axion gravity is a string-inspired model arising from the low energy effective action of heterotic string theory and an important candidate as alternative…
Impact of the disk thickness on X-ray reflection spectroscopy measurements
Ashutosh Tripathi, Askar B. Abdikamalov, Dimitry Ayzenberg +2
In a previous paper, we presented an extension of our reflection model RELXILL_NK to include the finite thickness of the accretion disk following the prescription in Taylor & Reyno…
Probing the near-horizon region of Cygnus X-1 with Suzaku and NuSTAR
Zuobin Zhang, Honghui Liu, Askar B. Abdikamalov +3
Astrophysical black holes are ideal laboratories for testing Einstein's theory of general relativity in the strong field regime. In this manuscript, we present an analysis of Suzak…
Implementation of a radial disk ionization profile in the RELXILL_NK model
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi +2
Very steep reflection emissivity profiles in the inner part of accretion disks are commonly found in the analysis of X-ray observations of black hole binaries and AGN, but there is…
Testing General Relativity with NuSTAR data of Galactic Black Holes
Ashutosh Tripathi, Yuexin Zhang, Askar B. Abdikamalov +5
Einstein's theory of General Relativity predicts that the spacetime metric around astrophysical black holes is described by the Kerr solution. In this work, we employ state-of-the-…
Reflection spectra of accretion disks illuminated by disk-like coronae
Shafqat Riaz, Askar B. Abdikamalov, Dimitry Ayzenberg +3
Relativistic reflection features in the X-ray spectra of black hole binaries and AGNs are thought to be produced through illumination of a cold accretion disk by a hot corona. In t…
Testing the Kerr Black Hole Hypothesis with GX 339-4 by a combined analysis of its thermal spectrum and reflection features
Ashutosh Tripathi, Askar B. Abdikamalov, Dimitry Ayzenberg +3
We analyze simultaneous observations with NuSTAR and Swift of the black hole binary GX 339-4 in which we clearly detect both a strong thermal component and prominent relativistic r…
Testing the Keplerian disk hypothesis using X-ray reflection spectroscopy
Ashutosh Tripathi, Biao Zhou, Askar B. Abdikamalov +3
The Novikov-Thorne model is the standard framework for the description of geometrically thin and optically thick accretion disks around black holes and is widely used to study the…
Impact of the returning radiation on the analysis of the reflection spectra of black holes
Shafqat Riaz, Michal Szanecki, Andrzej Niedzwiecki +2
A fraction of the electromagnetic radiation emitted from the surface of a geometrically thin and optically thick accretion disk of a black hole returns to the disk because of the s…
Shining X-rays on asymptotically safe quantum gravity
Biao Zhou, Askar B. Abdikamalov, Dimitry Ayzenberg +3
Asymptotically safe quantum gravity is a promising candidate scenario to provide a UV extension for the effective quantum field theory of Einstein's gravity. The theory has its fou…
Modeling bias in supermassive black hole spin measurements
Shafqat Riaz, Dimitry Ayzenberg, Cosimo Bambi +1
X-ray reflection spectroscopy (or iron line method) is a powerful tool to probe the strong gravity region of black holes, and currently is the only technique for measuring the spin…
Reflection spectra of thick accretion disks
Shafqat Riaz, Dimitry Ayzenberg, Cosimo Bambi +1
Relativistic reflection features are commonly observed in the X-ray spectra of stellar-mass and supermassive black holes and originate from illumination of the inner part of the ac…
Can the Slow-Rotation Approximation be used in Electromagnetic Observations of Black Holes?
Dimitry Ayzenberg, Kent Yagi, Nicolas Yunes
Future electromagnetic observations of black holes may allow us to test General Relativity in the strong-field regime. Such tests, however, require knowledge of rotating black hole…