scholarly journals Testing General Relativity in the Strong-Field Regime with Observations of Black Holes in the Electromagnetic Spectrum

2012 ◽  
Vol 124 (920) ◽  
pp. 1133-1134 ◽  
Author(s):  
Tim Johannsen
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Strong Field ◽  
Electromagnetic Spectrum

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

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.

scholarly journals Black holes in active galactic nuclei

2009 ◽  
Vol 5 (S261) ◽  
pp. 260-268
Author(s):  
M. J. Valtonen ◽  
S. Mikkola ◽  
D. Merritt ◽  
A. Gopakumar ◽  
H. J. Lehto ◽  
...  
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
Equations Of Motion ◽  
Binary Black Holes ◽  
Time Dynamic ◽  
Black Hole Spacetime ◽  
First Time ◽  
Black Hole Masses

AbstractSupermassive black holes are common in centers of galaxies. Among the active galaxies, quasars are the most extreme, and their black hole masses range as high as to 6⋅1010M⊙. Binary black holes are of special interest but so far OJ287 is the only confirmed case with known orbital elements. In OJ287, the binary nature is confirmed by periodic radiation pulses. The period is twelve years with two pulses per period. The last four pulses have been correctly predicted with the accuracy of few weeks, the latest in 2007 with the accuracy of one day. This accuracy is high enough that one may test the higher order terms in the Post Newtonian approximation to General Relativity. The precession rate per period is 39°.1 ± 0°.1, by far the largest rate in any known binary, and the (1.83 ± 0.01)⋅1010M⊙primary is among the dozen biggest black holes known. We will discuss the various Post Newtonian terms and their effect on the orbit solution. The over 100 year data base of optical variations in OJ287 puts limits on these terms and thus tests the ability of Einstein's General Relativity to describe, for the first time, dynamic binary black hole spacetime in the strong field regime. The quadrupole-moment contributions to the equations of motion allows us to constrain the ‘no-hair’ parameter to be 1.0 ± 0.3 which supports the black hole no-hair theorem within the achievable precision.

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 Venturing beyond the ISCO: detecting X-ray emission from the plunging regions around black holes

2020 ◽  
Vol 493 (4) ◽  
pp. 5532-5550 ◽  
Author(s):  
D R Wilkins ◽  
C S Reynolds ◽  
A C Fabian
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Energy Band ◽  
Strong Field ◽  
Time Lags ◽  
X Ray ◽  
Region Detection ◽  
Improving Accuracy

ABSTRACT We explore how X-ray reverberation around black holes may reveal the presence of the innermost stable circular orbit (ISCO), predicted by general relativity, and probe the dynamics of the plunging region between the ISCO and the event horizon. Being able to directly detect the presence of the ISCO and probe the dynamics of material plunging through the event horizon represents a unique test of general relativity in the strong field regime. X-ray reverberation off of the accretion disc and material in the plunging region is modelled using general relativistic ray tracing simulations. X-ray reverberation from the plunging region has a minimal effect on the time-averaged X-ray spectrum and the overall lag-energy spectrum, but is manifested in the lag in the highest frequency Fourier components, above $0.01\, c^{3}\, (GM)^{-1}$ (scaled for the mass of the black hole) in the 2–4 keV energy band for a non-spinning black hole or the 1–2 keV energy band for a maximally spinning black hole. The plunging region is distinguished from disc emission not just by the energy shifts characteristic of plunging orbits, but by the rapid increase in ionization of material through the plunging region. Detection requires measurement of time lags to an accuracy of 20 per cent at these frequencies. Improving accuracy to 12 per cent will enable constraints to be placed on the dynamics of material in the plunging region and distinguish plunging orbits from material remaining on stable circular orbits, confirming the existence of the ISCO, a prime discovery space for future X-ray missions.

A SIMPLIFIED TWO-BODY PROBLEM IN GENERAL RELATIVITY

2013 ◽  
Vol 22 (12) ◽  
pp. 1342029
Author(s):  
SHAHAR HOD
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Body Problem ◽  
Strong Field ◽  
Solvable Model ◽  
Weak Field ◽  
Fundamental Parameter ◽  
Two Body Problem ◽  
Weak Field Limit

General relativity, Einstein's theory of gravity, predicts a universe full of black holes and gravitational waves. The prospects of detecting gravitational waves from inspirals of compact astrophysical objects into supermassive black holes have made it highly important to analyze in detail the gravitational two-body problem. While the two-body problem in Newtonian gravity (the weak-field limit) has a well-defined compact analytic solution, the corresponding problem in general relativity (the strong-field regime) is very complex and cannot be solved analytically. In this paper, we propose to model the two-body problem in general relativity using the analytically solvable model of a ring of particles in orbit around a central black hole. We use our model to calculate the innermost stable circular orbit (ISCO) frequency which characterizes the two-body dynamics. Remarkably, our expression for the characteristic ISCO frequency through linear order in the ring's mass predicts with astonishing accuracy the actual value of this fundamental parameter.

scholarly journals From fundamental physics to tests with compact objects in metric-affine theories of gravity

2020 ◽  
Vol 29 (11) ◽  
pp. 2041007
Author(s):  
Diego Rubiera-Garcia
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Strong Field ◽  
Compact Objects ◽  
Fundamental Physics ◽  
Theories Of Gravity

This paper provides a short but comprehensible overview of some relevant aspects of metric-affine theories of gravity in relation to the physics and astrophysics of compact objects. We shall highlight the pertinence of this approach to supersede General Relativity on its strong-field regime, as well as its advantages and some of its difficulties. Moreover, we shall reflect on the present and future opportunities to test its predictions with relativistic and nonrelativistic stars, black holes, and other exotic horizonless compact objects.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

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