scholarly journals The confrontation between general relativity and experiment

2009 ◽  
Vol 5 (S261) ◽  
pp. 198-199
Author(s):  
Clifford M. Will
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Equivalence Principle ◽  
Gamma Ray ◽  
Strong Field ◽  
Weak Field ◽  
X Ray ◽  
Spacetime Geometry ◽  
Tests Of General Relativity ◽  
Laser Interferometric

AbstractWe review the experimental evidence for Einstein's general relativity. A variety of high precision null experiments confirm the Einstein Equivalence Principle, which underlies the concept that gravitation is synonymous with spacetime geometry, and must be described by a metric theory. Solar system experiments that test the weak-field, post-Newtonian limit of metric theories strongly favor general relativity. Binary pulsars test gravitational-wave damping and aspects of strong-field general relativity. During the coming decades, tests of general relativity in new regimes may be possible. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests via precise measurements of the properties of gravitational waves. Future efforts using X-ray, infrared, gamma-ray and gravitational-wave astronomy may one day test general relativity in the strong-field regime near black holes and neutron stars.

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.

scholarly journals Testing General Relativity with black hole X-ray data: a progress report

2021 ◽  
Author(s):  
Cosimo Bambi
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
Weak Field ◽  
Progress Report ◽  
X Ray ◽  
Binary Pulsars ◽  
The Past ◽  
Modern Physics ◽  
New Generation

AbstractEinstein’s theory of General Relativity is one of the pillars of modern physics. For decades, the theory has been mainly tested in the weak field regime with experiments in the Solar System and observations of binary pulsars. Thanks to a new generation of observational facilities, the past 5 years have seen remarkable changes in this field and there are now numerous efforts for testing General Relativity in the strong field regime with black holes and neutron stars using different techniques. Here I will review the work of my group at Fudan University devoted to test General Relativity with black hole X-ray data.

scholarly journals The first 5 years of gravitational-wave astrophysics

Science ◽  
2021 ◽  
Vol 372 (6546) ◽  
pp. eabc7397
Author(s):  
Salvatore Vitale
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Electromagnetic Waves ◽  
Gamma Ray ◽  
Direct Consequence ◽  
Compact Objects ◽  
Tests Of General Relativity ◽  
Astrophysical Objects ◽  
Progenitor Stars ◽  
The Universe

Gravitational waves are ripples in spacetime generated by the acceleration of astrophysical objects; a direct consequence of general relativity, they were first directly observed in 2015. Here, I review the first 5 years of gravitational-wave detections. More than 50 gravitational-wave events have been found, emitted by pairs of merging compact objects such as neutron stars and black holes. These signals yield insights into the formation of compact objects and their progenitor stars, enable stringent tests of general relativity, and constrain the behavior of matter at densities higher than that of an atomic nucleus. Mergers that emit both gravitational and electromagnetic waves probe the formation of short gamma-ray bursts and the nucleosynthesis of heavy elements, and they measure the local expansion rate of the Universe.

scholarly journals Slowly rotating topological neutron stars: universal relations and epicyclic frequencies

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Victor I. Danchev ◽  
Daniela D. Doneva ◽  
Stoytcho S. Yazadjiev
Keyword(s):  
General Relativity ◽  
Neutron Stars ◽  
Strong Field ◽  
Compact Objects ◽  
X Ray ◽  
Tests Of General Relativity ◽  
New Type ◽  
Theories Of Gravity ◽  
Scalar Theories ◽  
The Moment

AbstractIn the modern era of abundant X-ray detections and the increasing momentum of gravitational waves astronomy, tests of general relativity in strong field regime become increasingly feasible and their importance for probing gravity cannot be understated. To this end, we study the characteristics of slowly rotating topological neutron stars in the tensor-multi-scalar theories of gravity following the static study of this new type of compact objects by two of the authors. We explore the moment of inertia and verify that universal relations known from general relativity hold for this new class of compact objects. Furthermore, we study the properties of their innermost stable circular orbits and the epicyclic frequencies due to the latter’s hinted link to observational quantities such as quasi-periodic X-ray spectrum features.

scholarly journals Testing General Relativity with Gravitational Waves: An Overview

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 497
Author(s):  
N. V. Krishnendu ◽  
Frank Ohme
Keyword(s):  
General Relativity ◽  
General Theory ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Strong Field ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Tests Of General Relativity ◽  
Compact Binary

The detections of gravitational-wave (GW) signals from compact binary coalescence by ground-based detectors have opened up the era of GW astronomy. These observations provide opportunities to test Einstein’s general theory of relativity at the strong-field regime. Here we give a brief overview of the various GW-based tests of General Relativity (GR) performed by the LIGO-Virgo collaboration on the detected GW events to date. After providing details for the tests performed in four categories, we discuss the prospects for each test in the context of future GW detectors. The four categories of tests include the consistency tests, parametrized tests for GW generation and propagation, tests for the merger remnant properties, and GW polarization tests.

scholarly journals Gravitational waves from mountains in newly born millisecond magnetars

2021 ◽  
Vol 502 (4) ◽  
pp. 4680-4688
Author(s):  
Ankan Sur ◽  
Brynmor Haskell
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Massive Star ◽  
Gamma Ray ◽  
Dipole Radiation ◽  
X Ray ◽  
Binary Neutron Star ◽  
Spin Period ◽  
Lower Maximum ◽  
Wave Emission

ABSTRACT In this paper, we study the spin-evolution and gravitational-wave luminosity of a newly born millisecond magnetar, formed either after the collapse of a massive star or after the merger of two neutron stars. In both cases, we consider the effect of fallback accretion; and consider the evolution of the system due to the different torques acting on the star, namely the spin-up torque due to accretion and spin-down torques due to magnetic dipole radiation, neutrino emission, and gravitational-wave emission linked to the formation of a ‘mountain’ on the accretion poles. Initially, the spin period is mostly affected by the dipole radiation, but at later times, accretion spin the star up rapidly. We find that a magnetar formed after the collapse of a massive star can accrete up to 1 M⊙, and survive on the order of 50 s before collapsing to a black hole. The gravitational-wave strain, for an object located at 1 Mpc, is hc ∼ 10−23 at kHz frequencies, making this a potential target for next-generation ground-based detectors. A magnetar formed after a binary neutron star merger, on the other hand, accretes at the most 0.2 M⊙ and emits gravitational waves with a lower maximum strain of the order of hc ∼ 10−24, but also survives for much longer times, and may possibly be associated with the X-ray plateau observed in the light curve of a number of short gamma-ray burst.

scholarly journals Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

2020 ◽  
Vol 499 (4) ◽  
pp. 5986-5992
Author(s):  
Nikhil Sarin ◽  
Paul D Lasky ◽  
Gregory Ashton
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dipole Radiation ◽  
X Ray ◽  
Radiative Efficiency ◽  
Central Engine ◽  
Radiative Losses ◽  
Wave Emission ◽  
Prompt Emission

ABSTRACT The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as $n=4.85^{+0.11}_{-0.15}$ suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

scholarly journals Tests of weak equivalence principle with the gravitational wave signals in the LIGO–Virgo catalogue GWTC-1

2020 ◽  
Vol 499 (1) ◽  
pp. L53-L57
Author(s):  
Shu-Cheng Yang ◽  
Wen-Biao Han ◽  
Gang Wang
Keyword(s):  
Gravitational Wave ◽  
Equivalence Principle ◽  
Arrival Time ◽  
Gamma Ray ◽  
Weak Equivalence ◽  
Radio Bursts ◽  
Weak Equivalence Principle ◽  
Massive Galaxies ◽  
Binary Black Hole ◽  
Gravitational Theories

ABSTRACT The weak equivalence principle (WEP) is the cornerstone of gravitational theories. At the local scale, WEP has been tested to high accuracy by various experiments. On the intergalactic distance scale, WEP could be tested by comparing the arrival time of different messengers emitted from the same source. The gravitational time delay caused by massive galaxies is proportional to γ + 1, where the parameter γ is unity in general relativity. The values of γ for different massless particles should be different if WEP is violated, i.e. Δγ is used to indicate the deviation from WEP. So far, |Δγ| has been constrained with gamma-ray bursts, fast radio bursts, etc. Here, we report a new constraint of |Δγ| by using the gravitational wave data of binary black hole coalescences in the LIGO–Virgo catalogue GWTC-1. The best constraints imply that |Δγ| ≲ 10−15 at 90 per cent confidence level.

General Relativity

2017 ◽  
Author(s):  
Nicholas Manton ◽  
Nicholas Mee
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Field Equation ◽  
Einstein Field Equation ◽  
Kerr Metric ◽  
Gravitational Lenses ◽  
Field Equations ◽  
Spacetime Geometry ◽  
Tests Of General Relativity ◽  
Rotating Black Holes

This chapter presents the physical motivation for general relativity, derives the Einstein field equation and gives concise derivations of the main results of the theory. It begins with the equivalence principle, tidal forces in Newtonian gravity and their connection to curved spacetime geometry. This leads to a derivation of the field equation. Tests of general relativity are considered: Mercury’s perihelion advance, gravitational redshift, the deflection of starlight and gravitational lenses. The exterior and interior Schwarzschild solutions are discussed. Eddington–Finkelstein coordinates are used to describe objects falling into non-rotating black holes. The Kerr metric is used to describe rotating black holes and their astrophysical consequences. Gravitational waves are described and used to explain the orbital decay of binary neutron stars. Their recent detection by LIGO and the beginning of a new era of gravitational wave astronomy is discussed. Finally, the gravitational field equations are derived from the Einstein–Hilbert action.

scholarly journals Multiparameter Tests of General Relativity Using Multiband Gravitational-Wave Observations

2020 ◽  
Vol 125 (20) ◽  
Author(s):  
Anuradha Gupta ◽  
Sayantani Datta ◽  
Shilpa Kastha ◽  
Ssohrab Borhanian ◽  
K. G. Arun ◽  
...  
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Tests Of General Relativity
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