In this paper, we investigate the effects of a dark matter (DM) spike on neighborhood Sgr A*, black hole (BH) in center Milky Way galaxy. Our main goal is to whether current and future astronomical observations A* could detect presence such DM spike. At first, construct spacetime metric around static spherically symmetric BH with spike, later solution generalized for rotating using Newman-Janis-Azreg A\"{i}nou algorithm. For metric, use data S2 star orbiting determine analyze constraints two...

Recently, we have extended the X-ray reflection model relxill to test spacetime metric in strong gravitational field of astrophysical black holes. In present Letter, employ this analyze XMM-Newton, NuSTAR, and Swift data supermassive hole 1H0707-495 deviations from a Kerr parametrized by Johannsen deformation parameter $\alpha_{13}$. Our results are consistent with hypothesis that around is described solution.

Abstract We present the first X-ray reflection model for testing assumption that metric of astrophysical black holes is described by Kerr solution. employ formalism transfer function proposed Cunningham. The calculations spectrum a thin accretion disk are split into two parts: calculation and local at any emission point in disk. only depends on background takes account all relativistic effects (gravitational redshift, Doppler boosting, light bending). Our code computes spacetime Johannsen...

Abstract Astrophysical black hole systems are the ideal laboratories for testing Einstein’s theory of gravity in strong field regime. We have recently developed a framework that uses reflection spectrum to perform precision tests general relativity by Kerr hypothesis. In this paper, we analyze XMM-Newton and NuSTAR observations supermassive Seyfert 1 galaxy MCG–06–30–15 with our disk model. consider Johannsen metric deformation parameters α 13 22 , which quantify deviations from metric. For...

Abstract X-ray reflection spectroscopy is a powerful tool for probing the strong gravity region of black holes and can be used testing general relativity in field regime. Simplifications available relativistic models limit capability performing accurate measurements properties holes. In this paper, we present an extension model relxill _ nk which accretion disk has finite thickness rather than being infinitesimally thin. We employ geometry proposed by Taylor & Reynolds construct...

We present the study of a sample seven "bare" active galactic nuclei (AGN) observed with Suzaku. interpret spectrum these sources relativistic reflection component and we employ our model RELXILL_NK to test Kerr nature their supermassive black holes. constrain Johannsen deformation parameters $\alpha_{13}$ $\alpha_{22}$, in which metric is recovered when $\alpha_{13} = \alpha_{22} 0$. All measurements are consistent hypothesis that spacetime geometry around objects described by solution. For...

Weyl conformal symmetry can solve the problem spacetime singularities present in Einstein's gravity. In a recent paper, two of us have found singularity-free rotating black hole solution addition to mass $M$ and spin angular momentum $J$ hole, new has parameter, $L$, which here we consider be proportional mass. Since is conformally equivalent Kerr metric, photon trajectories are unchanged, while structure an accretion disk around affected by value parameter $L$. this show that X-ray data...

Electromagnetic observations of the radiation emitted by an accretion disk around a black hole, as well gravitational wave coalescing binaries, can be used to probe strong-field gravity. We here compare constraints that these two types impose on theory-agnostic, parametric deviations from Schwarzschild metric. On side, we begin computing leading-order deviation Hamiltonian binary system in quasi-circular orbit within post-Newtonian approximation, given deformation metrics each component....

Abstract In a previous paper, we tried to test the Kerr nature of stellar-mass black hole in GRS 1915+105 by analyzing NuSTAR data 2012 with our reflection model relxill _ nk . We found that choice intensity profile component is crucial and eventually were not able get any constraint on spacetime metric around 1915+105. present study same source Suzaku 2007. confirm plays an important role, but now find quite stringent constraints consistent hypothesis. The key differences respect are likely...

Abstract It is thought that the spacetime metric around astrophysical black holes well described by Kerr solution of Einstein’s gravity. However, robust observational evidence nature these objects still lacking. Here we fit X-ray spectrum stellar-mass hole in GS 1354–645 with a disk reflection model beyond gravity order test hypothesis. We consider Johannsen deformation parameters α 13 and 22 . The recovered for <?CDATA ${\alpha }_{13}={\alpha }_{22}=0$?> For = 0, our measurements spin...

Einstein's theory of general relativity has been extensively tested in weak gravitational fields, mainly with experiments the Solar System and observations radio pulsars, current data agree well theoretical predictions. Nevertheless, there are a number scenarios beyond gravity that have same predictions for fields present deviations only when becomes strong. Here, we try to test strong field regime. We fit x-ray spectrum supermassive black hole Ark 564 disk reflection model gravity, able...

Relativistic reflection features are commonly observed in the X-ray spectra of stellar-mass and supermassive black holes originate from illumination inner part accretion disk by a hot corona. All available relativistic models assume that is infinitesimally thin edge at innermost stable circular orbit or larger radius. However, we know several sources, especially among holes, have quite high mass rates. In such case, becomes geometrically thick expected to be inside orbit. this work, employ...

We present the public release version of relxill_nk, an X-ray reflection model for testing Kerr hypothesis and general relativity. This extends relxill that assumes black hole spacetime is described by metric. also relxilllp_nk, first non-Kerr with a lamppost corona configuration, as well all other models available in full relxill_nk package. In relevant relativistic effects are calculated through ray-tracing code can be applied to any well-behaved, stationary, axisymmetric, asymptotically...

Einstein-dilaton-Gauss-Bonnet gravity is a well-motivated alternative theory of that emerges naturally from string theory. While black hole solutions have been known in this numerical form for while, an approximate analytical metric was obtained recently by some us, which allows faster and more detailed analysis. Here we test the accuracy context X-ray reflection spectroscopy. We analyze innermost stable circular orbits (ISCO) relativistically broadened iron lines find both ISCO are...

According to the Blandford-Znajek mechanism, black hole jets are powered by rotational energy of compact object. In this work, we consider possibility that metric around holes may not be described Kerr solution and study how changes model. If mechanism is responsible for formation jets, estimate jet power in combination with another measurement can test nature candidates constrain possible deviations from solution. However, approach might become competitive respect other techniques only when...

We continue exploring the constraining capabilities of x-ray reflection spectroscopy to test Kerr-nature astrophysical black holes, and we present results our analysis two NuSTAR observations Cygnus X-1 in soft state. find that final measurement can strongly depend on assumption intensity profile. conclude is not suitable for tests general relativity using spectroscopy, discuss desired properties a source be good candidate studies.

We present nkbb, an XSPEC model for the thermal spectrum of thin accretion disks in parametric black hole spacetimes. employ Novikov-Thorne description disk and formalism transfer function proposed by Cunningham storing all relativistic effects spacetime metric. The current version assumes Johannsen metric, but it can be easily extended to any stationary, axisymmetric, asymptotically flat without pathological properties. used within package test Kerr nature astrophysical holes with...

Kaluza-Klein theory is a popular alternative of gravity, with both non-rotating and rotating black hole solutions known. This allows for the possibility that could be observationally tested. We present model which calculates reflection spectrum accretion disk system, where described by solution theory. also use this to analyze X-ray data from stella-mass in GRS 1915+105 provide constraints on free parameters holes.

X-ray reflection spectroscopy is a promising technique for testing general relativity in the strong field regime, as it can be used to test Kerr black hole hypothesis. In this context, parametrically deformed metrics proposed by Konoplya, Rezzolla \& Zhidenko (Phys. Rev. D93, 064015, 2016) form an important class of non-Kerr holes. We implement \textsc{relxill\_nk}, which framework we have developed holes using spectroscopy. perform qualitative analysis effect leading order strong-field...

Asymptotically safe quantum gravity is a promising candidate scenario to provide UV extension for the effective field theory of Einstein's gravity. The has its foundations on very successful framework theory, which been extensively tested electromagnetic and nuclear interactions. However, observational tests asymptotically are more challenging. Recently, rotating black hole metric inspired by proposed, this opens possibility astrophysical theory. In present paper, we show capabilities X-ray...

Binary black hole coalescence has its peak of gravitational wave generation during the "plunge," transition from quasicircular early motion to late quasinormal ringing. Although advances in numerical relativity have provided plunge waveforms, there is still no intuitive or phenomenological understanding plungecomparable that and stages. Here we make progress developing such by focusing on excitation ringing (QNR) plunge. We rely insights linear mathematics particle perturbation model for...

QPOs are a common feature in the X-ray power density spectrum of black hole binaries and potentially powerful tool to probe spacetime geometry around these objects. Here we discuss their constraining test Kerr hypothesis within relativistic precession model. We compare our results with constraints that can be obtained from gravitational waves iron line. find may provide very precise measurements, but they strongly affected by parameter degeneracy, it is difficult metric this approach absence...

We consider the family of singularity-free rotating black hole solutions in Einstein's conformal gravity found Bambi C. et al., JCAP, 05 (2017) 003 and we constrain value parameter L from analysis a NuSTAR observation stellar-mass GS 1354–645 during its outburst 2015. Our new constraint is much stronger than that previous work. Here obtain (99% confidence level, statistical uncertainty only).

There are many simplifications in current relativistic reflection models and this introduces systematic uncertainties the measurement of properties source. In paper, we study impact radiation crossing equatorial plane between black hole inner edge accretion disk; that is, produced by other side disk or circling one more times (higher order images). For slow-rotating holes with a larger plunging region, effect is not very sensitive to exact inclination angle disk. fast-rotating smaller weak...