204 citations · 1.8k across the 55 of their papers we have counts for
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Search for traversable wormholes in active galactic nuclei using X-ray data
Ashutosh Tripathi, Biao Zhou, Askar B. Abdikamalov +2
In a previous paper, one of us calculated iron K line profiles emitted from possible accretion disks around traversable wormholes as a first step to use X-ray reflection spectro…
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…
Modeling uncertainties in X-ray reflection spectroscopy measurements I: Impact of higher order disk images
Menglei Zhou, Dimitry Ayzenberg, Cosimo Bambi +1
There are many simplifications in current relativistic reflection models and this introduces systematic uncertainties in the measurement of the properties of the source. In this pa…
RELXILL_NK: A Black Hole Relativistic Reflection Model for Testing General Relativity
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi +1
In this paper, we briefly present RELXILL_NK, the first and currently only readily available model of the relativistic reflection spectrum of black hole accretion disks that includ…
Relativistic reflection spectra of super-spinning black holes
Biao Zhou, Ashutosh Tripathi, Askar B. Abdikamalov +4
We construct a relativistic reflection model in a non-Kerr spacetime in which, depending on the value of the deformation parameter of the metric, there are black hole solutions wit…
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…
Tests of the Kerr hypothesis with GRS 1915+105 using different RELXILL flavors
Yuexin Zhang, Askar B. Abdikamalov, Dimitry Ayzenberg +2
In a previous paper, we tried to test the Kerr nature of the stellar-mass black hole in GRS 1915+105 by analyzing NuSTAR data of 2012 with our reflection model RELXILL_NK. We found…
Testing general relativity with supermassive black holes using X-ray reflection spectroscopy
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi +7
In this paper, we review our current efforts to test General Relativity in the strong field regime by studying the reflection spectrum of supermassive black holes. So far we have a…
Constraining the Johannsen deformation parameter with black hole X-ray data
Ashutosh Tripathi, Askar B. Abdikamalov, Dimitry Ayzenberg +2
We extend our previous work on tests of the Kerr black hole hypothesis using X-ray reflection spectroscopy and we infer observational constraints on the Johannsen deformation param…
Testing the Kerr hypothesis using X-ray reflection spectroscopy with NuSTAR data of Cygnus X-1 in the soft state
Honghui Liu, Askar B. Abdikamalov, Dimitry Ayzenberg +4
We continue exploring the constraining capabilities of X-ray reflection spectroscopy to test the Kerr-nature of astrophysical black holes and we present the results of our analysis…
Black hole mimicker hiding in the shadow: Optical properties of the -metric
Askar B. Abdikamalov, Ahmadjon A. Abdujabbarov, Dimitry Ayzenberg +3
Can the observation of the "shadow" allow us to distinguish a black hole from a more exotic compact object? We study the motion of photons in a class of vacuum static axially-symme…
Testing General Relativity with X-ray reflection spectroscopy: The Konoplya-Rezzolla-Zhidenko parametrization
Sourabh Nampalliwar, Shuo Xin, Shubham Srivastava +6
X-ray reflection spectroscopy is a promising technique for testing general relativity in the strong field regime, as it can be used to test the Kerr black hole hypothesis. In this…
XSPEC model for testing the Kerr black hole hypothesis using the continuum-fitting method
Menglei Zhou, Askar B. Abdikamalov, Dimitry Ayzenberg +3
We present NKBB, an XSPEC model for the thermal spectrum of thin accretion disks in parametric black hole spacetimes. We employ the Novikov-Thorne model for the description of the…
Public Release of RELXILL_NK: A Relativistic Reflection Model for Testing Einstein's Gravity
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi +3
We present the public release version of relxill_nk, an X-ray reflection model for testing the Kerr hypothesis and general relativity. This model extends the relxill model that ass…
About the Kerr nature of the stellar-mass black hole in GRS 1915+105
Yuexin Zhang, Askar B. Abdikamalov, Dimitry Ayzenberg +4
We employ the accretion disk reflection model RELXILL_NK to test the spacetime geometry around the stellar-mass black hole in GRS 1915+105. We adopt the Johannsen metric with the d…
Constraints on the spacetime metric around seven "bare" AGNs using X-ray reflection spectroscopy
Ashutosh Tripathi, Jinli Yan, Yuchan Yang +12
We present the study of a sample of seven "bare" active galactic nuclei (AGN) observed with Suzaku. We interpret the spectrum of these sources with a relativistic reflection compon…