scholarly journals Prospects for probing strong gravity with a pulsar-black hole system

2012 ◽  
Vol 8 (S291) ◽  
pp. 171-176 ◽  
Author(s):  
N. Wex ◽  
K. Liu ◽  
R. P. Eatough ◽  
M. Kramer ◽  
J. M. Cordes ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Quadrupole Moment ◽  
Strong Field ◽  
Mass Measurement ◽  
Test System ◽  
Space Time ◽  
High Grade ◽  
Radio Telescopes ◽  
Strong Gravity

AbstractThe discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems, utilizing present and future radio telescopes, like FAST and SKA.

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.

OBSERVATIONAL CONSTRAINTS ON STRONG GRAVITY

2011 ◽  
Vol 20 (14) ◽  
pp. 2755-2760
Author(s):  
CHRIS DONE
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Strong Field ◽  
Field Tests ◽  
High Energy ◽  
Observational Constraints ◽  
Tests Of General Relativity ◽  
Strong Gravity ◽  
Accretion Flows ◽  
Spacetime Curvature

Accretion onto a black hole transforms the darkest objects in the universe to the brightest. The high energy radiation emitted from the accretion flow before it disappears forever below the event horizon lights up the regions of strong spacetime curvature close to the black hole, enabling strong field tests of General Relativity. I review the observational constraints on strong gravity from such accretion flows, and show how the data strongly support the existence of such fundamental General Relativistic features of a last stable orbit and the event horizon. However, these successes also imply that gravity does not differ significantly from Einstein's predictions above the event horizon, so any new theory of quantum gravity will be very difficult to test.

A ROBUST TEST OF GENERAL RELATIVITY IN SPACE

2007 ◽  
Vol 16 (12a) ◽  
pp. 2319-2324 ◽  
Author(s):  
JAMES GRABER
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Quadrupole Moment ◽  
Binary Systems ◽  
High Mass ◽  
Uniqueness Theorems ◽  
Mass Ratio ◽  
Intermediate Mass ◽  
Robust Test

LISA may make it possible to test the black-hole uniqueness theorems of general relativity, also called the no-hair theorems, by Ryan's method of detecting the quadrupole moment of a black hole using high-mass-ratio inspirals. This test can be performed more robustly by observing inspirals in earlier stages, where the simplifications used in making inspiral predictions by the perturbative and post-Newtonian methods are more nearly correct. Current concepts for future missions such as DECIGO and BBO would allow even more stringent tests by this same method. Recently discovered evidence supports the existence of intermediate-mass black holes (IMBHs). Inspirals of binary systems with one IMBH and one stellar-mass black hole would fall into the frequency band of proposed maximum sensitivity for DECIGO and BBO. This would enable us to perform the Ryan test more precisely and more robustly. We explain why tests based on observations earlier in the inspiral are more robust and provide preliminary estimates of possible optimal future observations.

scholarly journals Galactic center pulsar as a test of black hole existence and properties

1979 ◽  
Vol 84 ◽  
pp. 401-404
Author(s):  
B. Paczyński ◽  
V. Trimble
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Galactic Center ◽  
Strong Field ◽  
Field Tests ◽  
Central Black Hole ◽  
X Ray ◽  
Tests Of General Relativity ◽  
Period Orbit ◽  
Short Period

There is a reasonable chance of finding a (probably X-ray) pulsar in a short-period orbit around the galactic center. Such a pulsar can provide a test distinguishing a central black hole from a supermassive object or spinar. It also makes available a good clock in a region of space in which GM/Rc2 is much larger than solar system values, thus allowing strong-field tests of general relativity.

The Direct Detection of Gravitational Waves

2018 ◽  
pp. 106-109
Author(s):  
Alvaro De Rújula
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Space Time ◽  
New Era ◽  
The Third ◽  
Perfect Storm

Gravitational waves emitted by black hole mergers. The first LIGO event: GW150917, the coalescence of two black holes of twenty nine and thirty six solar masses into one of “only” sixty two. The remaining three solar masses were emitted as energy in gravitational waves, a gigantic and perfect storm in the fabric of space-time. This is the dawn of a new era: The opening of the third “window” through which to look at the sky. Yet another triumph of general relativity. How much progress astrophysics has made since my time as a student.

AN ANSWER TO THE MAIN BLACK HOLE PATHOLOGY: FORMING NONSINGULAR BLACK HOLES FROM DUST COLLAPSE

2009 ◽  
Vol 18 (14) ◽  
pp. 2221-2229 ◽  
Author(s):  
R. MAIER ◽  
I. DAMIÃO SOARES
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Nonlinear Resonance ◽  
Space Time ◽  
Low Energy ◽  
Spherically Symmetric ◽  
Energy Limit ◽  
Exterior Space

The dynamics of gravitational collapse is examined in the realm of string-based formalism of D-branes which encompasses general relativity as a low energy limit. A complete analytical solution is given to the spherically symmetric collapse of a pure dust star, including its matching with a corrected Schwarzschild exterior space–time. The collapse forms a black hole (an exterior event horizon) enclosing not a singularity but perpetually bouncing matter in the infinite chain of space–time maximal analytical extensions inside the outer event horizon. This chain of analytical extensions has a structure analogous to that of the Reissner–Nordstrom solution. The interior trapped bouncing matter has the possibility of being expelled by disruptive nonlinear resonance mechanisms.

scholarly journals The shape of the black hole photon ring: A precise test of strong-field general relativity

2020 ◽  
Vol 102 (12) ◽  
Author(s):  
Samuel E. Gralla ◽  
Alexandru Lupsasca ◽  
Daniel P. Marrone
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Strong Field

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 Constraints on General Relativity Geodesics by a Covariant Geometric Uncertainty Principle

2021 ◽  
Author(s):  
David Escors ◽  
Grazyna Kochan
Keyword(s):  
Mathematical Model ◽  
General Relativity ◽  
Black Hole ◽  
Quantum Gravity ◽  
Uncertainty Principle ◽  
Zero Point ◽  
Space Time ◽  
Planck Length ◽  
Exclusion Zone ◽  
Curvature Perturbation

General relativity is a theory for gravitation based on Riemannian geometry, difficult to compatibilize with quantum mechanics. This is evident in relativistic problems in which quantum effects cannot be discarded. For example in quantum gravity, gravitation of zero-point energy or events close to a black hole singularity. Here, we set up a mathematical model to select general relativity geodesics according to compatibility with the uncertainty principle. To achieve this, we derived a geometric expression of the uncertainty principle (GeUP). This formulation identified proper space-time length with Planck length by a geodesic-derived scalar. GeUP imposed a minimum allowed value for the interval of proper space-time which depended on the particular space-time geometry. GeUP forced the introduction of a “zero-point” curvature perturbation over flat Minkowski space, caused exclusively by quantum uncertainty but not to gravitation. When applied to the Schwarzschild metric and choosing radial-dependent geodesics, our mathematical model identified a particle exclusion zone close to the singularity, similar to calculations by loop quantum gravity. For a 2 black hole merger, this exclusion zone was shown to have a radius that cannot go below a value proportional to the energy/mass of the incoming black hole multiplied by Planck length.

scholarly journals Post-Newtonian gravitational and scalar waves in scalar-Gauss-Bonnet gravity

2021 ◽  
Author(s):  
Banafsheh Shiralilou ◽  
Tanja Hinderer ◽  
Samaya Nissanke ◽  
Nestor Ortiz ◽  
Helvi Witek
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Gravitational Wave ◽  
Strong Field ◽  
Field Tests ◽  
Theoretical Modelling ◽  
Bonnet Gravity ◽  
Weak Coupling Approximation ◽  
Tests Of Gravity ◽  
The Impact

Abstract Gravitational waves emitted by black hole binary inspiral and mergers enable unprecedented strong-field tests of gravity, requiring accurate theoretical modelling of the expected signals in extensions of General Relativity. In this paper we model the gravitational wave emission of inspiralling binaries in scalar Gauss-Bonnet gravity theories. Going beyond the weak-coupling approximation, we derive the gravitational waveform to relative first post-Newtonian order beyond the quadrupole approximation and calculate new contributions from nonlinear curvature terms. We also compute the scalar waveform to relative 0.5PN order beyond the leading -0.5PN order terms. We quantify the effect of these terms and provide ready-to-implement gravitational wave and scalar waveforms as well as the Fourier domain phase for quasi-circular binaries. We also perform a parameter space study, which indicates that the values of black hole scalar charges play a crucial role in the detectability of deviation from General Relativity. We also compare the scalar waveforms to numerical relativity simulations to assess the impact of the relativistic corrections to the scalar radiation. Our results provide important foundations for future precision tests of gravity.

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