152 citations · 1.3k across the 50 of their papers we have counts for
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Magnetic rigidity reveals the PeVatron acceleration region in SS 433
Jie Liao, Wancheng Xu, Lang Cui +10
PeVatrons are cosmic accelerators capable of driving particles to petaelectronvolt (PeV) energies. Recently, microquasar jets have emerged as compelling Galactic PeVatron candidate…
Dual AGN and Multiple SMBH Systems in the Era of SKAO
Q. D'Amato, L. Cui, R. Deane +23
We present a radio-oriented review of current strategies for the detection and characterization of dual active galactic nuclei (DAGN) and supermassive black hole binaries (SMBHBs),…
X-Ray Intraday Variability of the Blazar OJ 287 Observed with XMM-Newton
Tao Huang, Alok C. Gupta, Lang Cui +4
We present X-ray intraday variability, cross-correlated variability, and power spectrum density analysis of the binary black hole blazar candidate OJ 287. The X-ray pointed observa…
Probable Quasi-Periodic Oscillations in the {\tt TESS} observations of blazars in the Swift X-ray Survey
Ashutosh Tripathi, Paul J. Wiita, Krista Lynne Smith
This work presents possible quasi-periodic oscillations in the Transiting Exoplanet Survey Satellite observations of blazars that are in the 157-month hard X-ray survey done by Swi…
Application of time-series analysis methods to a multiple-sector TESS observations: the case of the radio-loud blazar 3C 371
Ashutosh Tripathi, Paul J. Wiita, Ryne Dingler +4
We present various time series analysis methods to analyze multiple-sector observations of bright AGN from the Transiting Exoplanet Survey Satellite (TESS) and examine whether issu…
Revisiting radio variability of the blazar 3C 454.3
Ashutosh Tripathi, Alok C. Gupta, Krista Lynne Smith +7
We examine lengthy radio light curves of the flat spectrum radio galaxy 3C 454.3 for possible quasi-periodic oscillations (QPOs). The data used in this work were collected at five…
Tracking the jet-like corona of black hole Swift J1727.8-1613 during a flare state through Type-C quasi-periodic oscillations
Jie Liao, Ning Chang, Lang Cui +10
Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients typically manifest in the low-hard and hard-intermediate states. This study presents a detailed spectral an…
Tests of the Kerr Hypothesis with MAXI J1803-298 Using Different RELXILL_NK Flavors
Jie Liao, M. Ghasemi-Nodehi, Lang Cui +3
Iron line spectroscopy has been one of the leading methods not only for measuring the spins of accreting black holes but also for testing fundamental physics. Basing on such a meth…
Search for Quasi-Periodic Oscillations in TESS light curves of bright Fermi Blazars
Ashutosh Tripathi, Krista Lynne Smith, Paul J. Wiita +1
In a previous paper, we reported evidence for quasi-periodicities in the \textsl{TESS} light curves of BL Lacerate and two other blazars found serendipitously in the SDSS AGN catal…
Testing General Relativity with NuSTAR data of Galactic Black Holes : II
Ashutosh Tripathi, Swarnim Shashank, Gitika Mall +1
General relativity predicts the spacetime metric around an astrophysical black hole to be described by the Kerr solution, which is a massive rotating black hole without any residua…
Optical Quasi-periodic Oscillations in the TESS light curves of three blazars
Ashutosh Tripathi, Krista Lynne Smith, Paul J. Wiita +1
We report the time series analysis of TESS light curves of three blazars, BL Lacertae, 1RXS J111741.0+254858, and 1RXS J004519.6+212735, obtained using a customized approach for ex…
Multi-wavelength temporal variability of the blazar PKS 1510-089
Q. Yuan, Pankaj Kushwaha, Alok C. Gupta +13
We perform correlation and periodicity search analyses on long-term multi-band light curves of the FSRQ 1510-089 observed by the space-based Fermi--Large Area Telescope in gamma-ra…
Impact of ionization and electron density gradients in X-ray reflection spectroscopy measurements
Gitika Mall, Ashutosh Tripathi, Askar B. Abdikamalov +1
The models currently used for the analysis of the reflection spectra of black holes usually assume a disk with constant ionization and electron density. However, there is some deba…
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…
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…
Quasi-Periodic Oscillations in the long term radio light curves of the blazar AO 0235+164
Ashutosh Tripathi, Alok C. Gupta, Margo F. Aller +4
We present time series analyses of three-decade long radio observations of the BL Lacertae object AO 0235+164 made at the University of Michigan Radio Astronomical Observatory oper…
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-…
Towards precision measurements of accreting black holes using X-ray reflection spectroscopy
Cosimo Bambi, Laura W. Brenneman, Thomas Dauser +14
Relativistic reflection features are commonly observed in the X-ray spectra of accreting black holes. In the presence of high quality data and with the correct astrophysical model,…
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…