scholarly journals Testing General Relativity with Supermassive Black Holes Using X-Ray Reflection Spectroscopy

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 2 ◽  
Author(s):  
Askar B. Abdikamalov ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
Sourabh Nampalliwar ◽  
Ashutosh Tripathi ◽  
...  
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Strong Field ◽  
Supermassive Black Holes ◽  
Kerr Solution ◽  
Reflection Spectroscopy ◽  
Systematic Uncertainties ◽  
Preliminary Study ◽  
Spacetime Metric ◽  
The Impact

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 analyzed 11 sources with observations of NuSTAR, Suzaku, Swift, and XMM-Newton. Our results are consistent with General Relativity, according to which the spacetime metric around astrophysical black holes should be well approximated by the Kerr solution. We discuss the systematic uncertainties in our model and we present a preliminary study on the impact of some of them on the measurement of the spacetime metric.

scholarly journals Impact of the reflection model on the estimate of the properties of accreting black holes

2020 ◽  
Vol 498 (3) ◽  
pp. 3565-3577
Author(s):  
Ashutosh Tripathi ◽  
Honghui Liu ◽  
Cosimo Bambi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Strong Field ◽  
Quality Data ◽  
X Ray ◽  
Black Hole Binaries ◽  
Systematic Uncertainties ◽  
Reflection Model ◽  
Hot Corona ◽  
The Impact

ABSTRACT Relativistic reflection features in the X-ray spectra of black hole binaries and active galactic nuclei originate from illumination of the inner part of the accretion disc by a hot corona. In the presence of high quality data and with the correct astrophysical model, X-ray reflection spectroscopy can be quite a powerful tool to probe the strong gravity region, study the morphology of the accreting matter, measure black hole spins, and even test Einstein’s theory of general relativity in the strong field regime. There are a few relativistic reflection models available today and developed by different groups. All these models present some differences and have a number of simplifications introducing systematic uncertainties. The question is whether different models provide different measurements of the properties of black holes and how to arrive at a common model for the whole X-ray astronomy community. In this paper, we start exploring this issue by analysing a Suzaku observation of the stellar-mass black hole in GRS 1915+105 and simultaneous XMM–Newton and NuSTAR observations of the supermassive black hole in MCG-6-30-15. The relativistic reflection component of these sources is fitted with relconv × reflionx, relconv × xillver, and relxill. We discuss the differences and the impact on the study of accreting black holes.

scholarly journals Driven black holes: from Kolmogorov scaling to turbulent wakes

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Tomas Andrade ◽  
Christiana Pantelidou ◽  
Julian Sonner ◽  
Benjamin Withers
Keyword(s):  
Nonlinear Dynamics ◽  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
De Sitter ◽  
Event Horizons ◽  
Binary Mergers ◽  
Tidal Deformations ◽  
Proof Of Principle

Abstract General relativity governs the nonlinear dynamics of spacetime, including black holes and their event horizons. We demonstrate that forced black hole horizons exhibit statistically steady turbulent spacetime dynamics consistent with Kolmogorov’s theory of 1941. As a proof of principle we focus on black holes in asymptotically anti-de Sitter spacetimes in a large number of dimensions, where greater analytic control is gained. We focus on cases where the effective horizon dynamics is restricted to 2+1 dimensions. We also demonstrate that tidal deformations of the horizon induce turbulent dynamics. When set in motion relative to the horizon a deformation develops a turbulent spacetime wake, indicating that turbulent spacetime dynamics may play a role in binary mergers and other strong-field phenomena.

The stellar graveyard

2019 ◽  
pp. 177-206
Author(s):  
Nils Andersson
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
Fermi Gases ◽  
The 1950S

This chapter introduces the different classes of compact objects—white dwarfs, neutron stars, and black holes—that are relevant for gravitational-wave astronomy. The ideas are placed in the context of developing an understanding of the likely endpoint(s) of stellar evolution. Key ideas like Fermi gases and the Chandrasekhar mass are discussed, as is the emergence of general relativity as a cornerstone of astrophysics in the 1950s. Issues associated with different formation channels for, in particular, black holes are considered. The chapter ends with a discussion of the supermassive black holes that are found at the centre of galaxies.

scholarly journals Reflection spectra of thick accretion discs

2019 ◽  
Vol 491 (1) ◽  
pp. 417-426 ◽  
Author(s):  
Shafqat Riaz ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
Sourabh Nampalliwar
Keyword(s):  
Black Holes ◽  
Circular Orbit ◽  
Supermassive Black Holes ◽  
Accretion Disc ◽  
High Mass ◽  
Model Parameters ◽  
Reflection Spectra ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit ◽  
The Impact

ABSTRACT 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 accretion disc by a hot corona. All the available relativistic reflection models assume that the disc is infinitesimally thin and the inner edge is at the innermost stable circular orbit or at a larger radius. However, we know that several sources, especially among supermassive black holes, have quite high-mass accretion rates. In such a case, the accretion disc becomes geometrically thick and the inner edge of the disc is expected to be inside the innermost stable circular orbit. In this work, we employ the Polish donut model to describe geometrically thick discs and we study the iron-line shapes from similar systems. We also simulate full reflection spectra and we analyse the simulated observations with a thin disc relativistic reflection model to determine the impact of the disc structure on the estimation of the model parameters, in particular in the case of tests of the Kerr hypothesis.

scholarly journals From galactic nuclei to the halo outskirts: tracing supermassive black holes across cosmic history and environments

2020 ◽  
Vol 495 (4) ◽  
pp. 4681-4706 ◽  
Author(s):  
David Izquierdo-Villalba ◽  
Silvia Bonoli ◽  
Massimo Dotti ◽  
Alberto Sesana ◽  
Yetli Rosas-Guevara ◽  
...  
Keyword(s):  
Black Holes ◽  
Cosmic Time ◽  
Mass Function ◽  
Supermassive Black Holes ◽  
Dominant Type ◽  
Central Regions ◽  
Mass Assembly ◽  
The One ◽  
Gas Accretion ◽  
The Impact

ABSTRACT We study the mass assembly and spin evolution of supermassive black holes (BHs) across cosmic time as well as the impact of gravitational recoil on the population of nuclear and wandering BHs (wBHs) by using the semi-analytical model L-Galaxies run on top of Millennium merger trees. We track spin changes that BHs experience during both coalescence events and gas accretion phases. For the latter, we assume that spin changes are coupled with the bulge assembly. This assumption leads to predictions for the median spin values of z = 0 BHs that depend on whether they are hosted by pseudo-bulges, classical bulges or ellipticals, being $\overline{a} \sim 0.9$, 0.7 and 0.4, respectively. The outcomes of the model display a good consistency with $z \le 4$ quasar luminosity functions and the $z = 0$ BH mass function, spin values, and BH correlation. Regarding the wBHs, we assume that they can originate from both the disruption of satellite galaxies (orphan wBH) and ejections due to gravitational recoils (ejected wBH). The model points to a number density of wBHs that increases with decreasing redshift, although this population is always $\rm {\sim}2\, dex$ smaller than the one of nuclear BHs. At all redshifts, wBHs are typically hosted in $\rm {\it M}_{halo} \gtrsim 10^{13} \, M_{\odot }$ and $\rm {\it M}_{stellar} \gtrsim 10^{10} \, M_{\odot }$, being orphan wBHs the dominant type. Besides, independently of redshift and halo mass, ejected wBHs inhabit the central regions (${\lesssim}\rm 0.3{\it R}_{200}$) of the host DM halo, while orphan wBH linger at larger scales (${\gtrsim}\rm 0.5{\it R}_{200}$). Finally, we find that gravitational recoils cause a progressive depletion of nuclear BHs with decreasing redshift and stellar mass. Moreover, ejection events lead to changes in the predicted local BH–bulge relation, in particular for BHs in pseudo-bulges, for which the relation is flattened at $\rm {\it M}_{bulge} \gt 10^{10.2}\, M_{\odot }$ and the scatter increase up to ${\sim}\rm 3\, dex$.

Detecting Blackholes through Gravitational Waves

2014 ◽  
Author(s):  
Charles D. Bailyn
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Electromagnetic Radiation ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Stellar Mass ◽  
Supermassive Black Holes ◽  
Current Technology

This chapter looks at the detection of black holes through gravitational waves. While further improvements can be expected in the ability to detect and measure electromagnetic radiation, it is possible that the next great advances in observational astrophysics will come from the detection of other kinds of information altogether. Currently, there is a great excitement about the possibility of directly detecting an entirely new “celestial messenger,” namely, gravitational radiation. The existence of gravitational waves is a prediction of general relativity, and current technology is very close to being able to detect them directly. The strongest sources of gravitational radiation are expected to be merging black holes. Since such mergers are expected to occur, both between stellar-mass and supermassive black holes, the detection of gravitational radiation would provide a new way not only to explore gravitational physics but also to look for and to study celestial black holes.

scholarly journals Atomic X-ray spectroscopy of accreting black holes

2005 ◽  
Vol 83 (12) ◽  
pp. 1179-1242 ◽  
Author(s):  
D A Liedahl ◽  
D F Torres
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Strong Field ◽  
Electromagnetic Spectrum ◽  
Field Equations ◽  
X Ray ◽  
Physical Conditions ◽  
Luminous Objects

Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation across the electromagnetic spectrum, each energy band providing access to rather distinct regimes of physical conditions and geometric scale. X-ray emission probes the innermost regions of the accretion disk, where relativistic effects prevail. While this has been known for decades, it also has been acknowledged that inferring physical conditions in the relativistic regime from the behavior of the X-ray continuum is problematic and not satisfactorily constraining. With the discovery in the 1990s of iron X-ray lines bearing signatures of relativistic distortion came the hope that such emission would more firmly constrain models of disk accretion near black holes, as well as provide observational criteria by which to test general relativity in the strong field limit. Here, we provide an introduction to this phenomenon. While the presentation is intended to be primarily tutorial in nature, we aim also to acquaint the reader with trends in current research. To achieve these ends, we present the basic applications of general relativity that pertain to X-ray spectroscopic observations of black hole accretion-disk systems, focusing on the Schwarzschild and Kerr solutions to the Einstein field equations. To this, we add treatments of the fundamental concepts associated with the theoretical and modeling aspects of accretion disks, as well as relevant topics from observational and theoretical X-ray spectroscopy.PACS Nos.: 32.30.Rj, 32.80.Hd, 95.30.Dr, 95.30.Sf, 95.85.Nv, 97.10.Gz. 97.80.Jp, 98.35.Mp, 98.62.Mw

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