相关论文: Tests of the Kerr Hypothesis with MAXI J1803-298 U…
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 reflection features. We employ NKBB and RELXILL_NK, which are…
Astrophysical black hole candidates are thought to be the Kerr black holes of general relativity. However, macroscopic deviations from the Kerr background are predicted by a number of scenarios beyond Einstein's gravity. X-ray reflection…
We present our analysis of MAXI J1813-095 during its hard state ``stalled'' outburst in 2018. This self-consistent analysis has been carried out using \NICER, \Swift, \Chandra, and {\NuSTAR} throughout seven observations of MAXI J1813-095.…
Astrophysical black hole systems are the ideal laboratories for testing Einstein's theory of gravity in the strong field regime. We have recently developed a framework which uses the reflection spectrum of black hole systems to perform…
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 deformation parameters $\alpha_{13}$ and $\alpha_{22}$, for…
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 test the Kerr black hole hypothesis with the stellar-mass…
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 includes non-Kerr solutions for the black hole spacetime, thus…
MAXI J1803-298, a newly-discovered Galactic transient and black hole candidate, was first detected by \emph{MAXI}/GSC on May 1st, 2021. In this paper, we present a detailed spectral analysis of MAXI J1803-298. Utilizing the X-ray reflection…
We present the broadband spectral analysis of all the six hard, intermediate and soft state NuSTAR observations of the recently discovered transient black hole X-ray binary MAXI J1348-630 during its first outburst in 2019. We first model…
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 that the choice of the intensity profile of the reflection…
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 Suzaku and NuSTAR spectra of the black hole binary Cygnus X-1…
The transient black hole X-ray binary MAXI J1803-298 was discovered on 2021 May 1, as it went into outburst from a quiescent state. As the source rose in flux it showed periodic absorption dips and fit the timing and spectral…
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 parameter $\epsilon_3$. We analyze a NuSTAR observation of the…
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 have been developed for testing fundamental physics. In the…
The iron K$\alpha$ line commonly observed in the X-ray spectrum of both stellar-mass and supermassive black hole candidates originates from X-ray fluorescence of the inner accretion disk. Accordingly, it can be used to map the spacetime…
In a recent paper [Ghasemi-Nodehi & Bambi, EPJC 76 (2016) 290], we have proposed a new parametrization for testing the Kerr nature of astrophysical black hole candidates. In the present work, we study the possibility of constraining the…
The spacetime geometry around astrophysical black holes is well approximated by the Kerr metric, but deviations from standard predictions are possible in a number of scenarios beyond Einstein's gravity and in the presence of exotic matter.…
We report on a NuSTAR observation of the recently discovered bright black hole candidate MAXI J1535-571. NuSTAR observed the source on MJD 58003 (five days after the outburst was reported). The spectrum is characteristic of a black hole…
Einstein's gravity has undergone extensive tests in the weak field gravitational limit, with results in agreement with theoretical predictions. There exist theories beyond general relativity (GR) which modify gravity in the strong field…
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 debate on the impact of these assumptions on the estimate of the…