The gravitational rainbow beyond Einstein gravity

2019 ◽  
Vol 28 (05) ◽  
pp. 1942003 ◽  
Author(s):  
Claudia de Rham
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Upper Bound ◽  
Degrees Of Freedom ◽  
Direct Detection ◽  
Einstein Gravity ◽  
Observable Universe ◽  
Basic Properties ◽  
Speed Of Propagation

The recent direct detection of gravitational waves have been successfully used to examine the basic properties of the gravitational degrees of freedom. They set an upper bound on their mass and constrain their speed of propagation with unprecedented accuracy. Within the current realm of observational and theoretical constraints, we explore the possibility for gravity to depart from general relativity (GR) in the infrared and derive the implications on our observable Universe. We also investigate whether these types of models could ever enjoy a standard analytic UV completion.

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.

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.

scholarly journals Recent Observations of Gravitational Waves by LIGO and Virgo Detectors

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 137
Author(s):  
Andrzej Królak ◽  
Paritosh Verma
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Direct Detection ◽  
Nobel Prize Winner ◽  
Short Introduction ◽  
Interferometric Detectors ◽  
Laser Interferometric

In this paper we present the most recent observations of gravitational waves (GWs) by LIGO and Virgo detectors. We also discuss contributions of the recent Nobel prize winner, Sir Roger Penrose to understanding gravitational radiation and black holes (BHs). We make a short introduction to GW phenomenon in general relativity (GR) and we present main sources of detectable GW signals. We describe the laser interferometric detectors that made the first observations of GWs. We briefly discuss the first direct detection of GW signal that originated from a merger of two BHs and the first detection of GW signal form merger of two neutron stars (NSs). Finally we present in more detail the observations of GW signals made during the first half of the most recent observing run of the LIGO and Virgo projects. Finally we present prospects for future GW observations.

scholarly journals The past, present and future of gravitational wave astronomy

2021 ◽  
pp. 1-1
Author(s):  
H. Leverenz ◽  
M.D. Filipovic
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Nobel Prize ◽  
Direct Detection ◽  
Albert Einstein ◽  
Particle Measurements ◽  
The Past ◽  
Cosmic Scale ◽  
Nobel Prize In Physics

Gravitational Waves (GWs) have become a major source of insight in Multi Messenger Astronomy since their first direct detection in 2015 (Abbott et al. 2016) where the Nobel prize in Physics was awarded in 2017 to LIGO founders Barry C. Barish, Kip S. Thorne, and Rainer Weiss. They complement electromagnetic and particle measurements by providing cosmic scale evidence which cannot be detected in any other way. Their rise to prominence has not been straightforward since the founder of general relativity, Albert Einstein, who predicted GWs, was nevertheless skeptical of their existence and detectability. This skepticism put a damper on Gravitational Wave (GW) research that was not overcome until the 1950's, the decade of Einstein's death. Since then, ever more sensitive GW detectors have been designed for construction on earth and in space. Each of these detector approaches was designed to expand the types of cosmic events that could be detected.

scholarly journals From Einstein’s Theory to Gravity’s Chirp

2017 ◽  
Vol 13 (S337) ◽  
pp. 127-127
Author(s):  
Joseph H. Taylor
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Theoretical Work ◽  
Physical Reality ◽  
Quantitative Agreement ◽  
Field Equations ◽  
Experimental Proof ◽  
Quarter Century ◽  
Binary Pulsar

The tortuous journey from theoretical suspicions to direct detection of gravitational waves took a hundred years and followed a crooked course. The field equations of general relativity evidently have wave-like solutions, but physical reality of these implied waves was doubted by many — including Einstein himself — for nearly fifty years. The question of physical reality was settled theoretically by the late 1950s, but for several more decades serious questions remained about what types of astrophysical systems might generate gravitational waves, and with what energies. The discovery of binary pulsar PSR B1913+16 led to dedicated development of much more accurate pulsar timing techniques, and results of these experiments motivated further theoretical work to clear up the quantitative questions about energy generation. By the late 1980s the generation of gravitational waves by the Hulse-Taylor binary pulsar was firmly established to be in quantitative agreement with general relativity. This experimental proof was almost surely a prerequisite for the funding of LIGO, the Laser Interferometer Gravitational-Wave Observatory, in 1992, which after nearly another quarter century achieved the first direct detection of gravitational waves.

scholarly journals Gravitational waves in the extended theory of gravity

2021 ◽  
Author(s):  
Sourav Roy Chowdhury ◽  
Maxim Khlopov
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Degrees Of Freedom ◽  
Standard Theory ◽  
New Approach ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Theory Of Gravity ◽  
New Formula ◽  
Extended Theories

Extended theories of gravity are considered as a new approach for solving the infrared and ultraviolet scale problems; the standard theory of gravity (general relativity) and observational evidence of gravitational waves and subsequent identification of the number of existing polarizations are an effective tool for testing general relativity and extended theories of gravity. The Newman–Penrose method is used to characterize the polarization modes for specific forms of [Formula: see text] in the present study. Both the forms of the [Formula: see text] theory belong to far more general variational class of gravitational waves, capable of presenting up to six separate polarizations states. We have introduced a new [Formula: see text] gravity model as an attempt to have a theory with more parametric regulations so that the model can be used to describe existing issues and discover different directions in gravity physics. The primary goal of this research is to look into the properties of gravitational waves with new cases. The model shows the existence of scalar degrees of freedom in [Formula: see text] gravity metric notation.

scholarly journals Pulsars are cool. Seriously.

2012 ◽  
Vol 8 (S291) ◽  
pp. 3-10 ◽  
Author(s):  
Scott M. Ransom
Keyword(s):  
General Relativity ◽  
Interstellar Medium ◽  
Gravitational Waves ◽  
Stellar Evolution ◽  
Direct Detection ◽  
Dense Matter ◽  
Tests Of General Relativity ◽  
The Future ◽  
Basic Physics ◽  
Over 40 Years

AbstractEver since the first pulsar was discovered by Bell and Hewish over 40 years ago, we've known that not only are pulsars fascinating and truly exotic objects, but that we can use them as powerful tools for basic physics and astrophysics as well. Taylor and Hulse hammered these views home with their discovery and timing of the spectacular “binary pulsar” in the 1970s and 1980s. In the last two decades a host of surprises and a promise of phenomenal scientific riches in the future has come from the millisecond pulsars. As our instrumentation has become more sensitive and better suited to measuring the pulses from these objects, they've given us new tests of general relativity, fantastic probes of the interstellar medium, constraints on the physics of ultra-dense matter, new windows into binary and stellar evolution, and the promise of a direct detection of gravitational waves. These things really are cool, and there is much more we will do with them in the future.

scholarly journals Testing General Relativity with Pulsar Timing Arrays

2012 ◽  
Author(s):  
Sydney Chamberlin ◽  
Xavier Siemens
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Promising Tool ◽  
Pulsar Timing ◽  
Theories Of Gravity ◽  
Statistical Detection ◽  
Detection Strategies ◽  
Pulsar Timing Array ◽  
The Universe

Pulsar timing arrays are a promising tool for probing the universe through gravitational radiation. A variety of astrophysical and cosmological sources are expected to contribute to a stochastic background of gravitational waves (GWs) in the pulsar timing array (PTA) frequency band. Direct detection of GWs will provide a new mechanism to test General Relativity and requires the development of robust statistical detection strategies. Here, we investigate the overlap reduction function, a term present in the optimal detection statistic, for GWs in various metric theories of gravity. We show that PTA sensitivity increases for non-transverse gravitational waves when pulsar pairs have small angular separations in the sky. 

On the direct detection of gravitational waves

2016 ◽  
Vol 186 (10) ◽  
pp. 1133-1152 ◽  
Author(s):  
V.I. Pustovoit
Keyword(s):  
Gravitational Waves ◽  
Direct Detection
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