scholarly journals Asymptotic behavior of null geodesics near future null infinity: Significance of gravitational waves

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Masaya Amo ◽  
Keisuke Izumi ◽  
Yoshimune Tomikawa ◽  
Hirotaka Yoshino ◽  
Tetsuya Shiromizu
Keyword(s):  
Asymptotic Behavior ◽  
Gravitational Waves ◽  
Null Infinity ◽  
Null Geodesics ◽  
Near Future ◽  
Future Null Infinity

scholarly journals On the local extension of the future null infinity

2018 ◽  
Vol 110 (1) ◽  
pp. 73-133 ◽  
Author(s):  
Junbin Li ◽  
Xi-Ping Zhu
Keyword(s):  
Null Infinity ◽  
Local Extension ◽  
The Future ◽  
Future Null Infinity

scholarly journals Trapping of null geodesics in slowly rotating spacetimes

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Jaroslav Vrba ◽  
Martin Urbanec ◽  
Zdeněk Stuchlík ◽  
John C. Miller
Keyword(s):  
Angular Velocity ◽  
Gravitational Waves ◽  
Compact Objects ◽  
Trapping Efficiency ◽  
Uniform Density ◽  
Slow Rotation ◽  
Null Geodesics ◽  
Effective Potentials ◽  
First Order ◽  
Simple Generalization

AbstractExtremely compact objects containing a region of trapped null geodesics could be of astrophysical relevance due to trapping of neutrinos with consequent impact on cooling processes or trapping of gravitational waves. These objects have previously been studied under the assumption of spherical symmetry. In the present paper, we consider a simple generalization by studying trapping of null geodesics in the framework of the Hartle–Thorne slow-rotation approximation taken to first order in the angular velocity, and considering a uniform-density object with uniform emissivity for the null geodesics. We calculate effective potentials and escape cones for the null geodesics and how they depend on the parameters of the spacetimes, and also calculate the “local” and “global” coefficients of efficiency for the trapping. We demonstrate that due to the rotation the trapping efficiency is different for co-rotating and retrograde null geodesics, and that trapping can occur even for $$R>3GM/c^2$$ R > 3 G M / c 2 , contrary to what happens in the absence of rotation.

scholarly journals INFLATION, QUANTUM FIELDS, AND CMB ANISOTROPIES

2009 ◽  
Vol 18 (14) ◽  
pp. 2329-2335 ◽  
Author(s):  
IVÁN AGULLÓ ◽  
JOSÉ NAVARRO-SALAS ◽  
GONZALO J. OLMO ◽  
LEONARD PARKER
Keyword(s):  
Cosmic Microwave Background ◽  
Gravitational Waves ◽  
Early Universe ◽  
Inflationary Cosmology ◽  
Quantum Field ◽  
Quantum Fields ◽  
Microwave Background ◽  
Cosmological Inflation ◽  
Near Future ◽  
Field Renormalization

Inflationary cosmology has proven to be the most successful at predicting the properties of the anisotropies observed in the cosmic microwave background (CMB). In this essay we show that quantum field renormalization significantly influences the generation of primordial perturbations and hence the expected measurable imprint of cosmological inflation on the CMB. However, the new predictions remain in agreement with observation, and in fact favor the simplest forms of inflation. In the near future, observations of the influence of gravitational waves from the early universe on the CMB will test our new predictions.

scholarly journals Post-Newtonian Expansion of Gravitational Waves from a Particle in Circular Orbits around a Rotating Black Hole: Effects of Black Hole Absorption

1999 ◽  
Vol 183 ◽  
pp. 163-163
Author(s):  
Hideyuki Tagoshi ◽  
Shuhei Mano ◽  
Eiichi Takasugi
Keyword(s):  
Black Hole ◽  
Gravitational Waves ◽  
Energy Absorption ◽  
Absorption Rate ◽  
Kerr Black Hole ◽  
Compact Binaries ◽  
Wave Forms ◽  
Teukolsky Equation ◽  
Interferometric Detectors ◽  
Near Future

Coalescing compact binaries are the most promising candidates for detection by near-future, ground based laser interferometric detectors. It is very important to investigate detailed wave forms from coalescing compact binaries. When one (or two) of the stars is a black hole, some of those waves are absorbed by the black hole. Here, we consider a case when a test particle moves circular orbit on the equatorial plane around a Kerr black hole, and calculate the the energy absorption rate by the black hole. We adopt an analytic techniques for the Teukolsky equation which was found by Mano, Suzuki, and Takasugi (1996). We calculated the energy absorption rate to O((v/c)13) beyond the Newtonian-quadrupole formula of gravitational waves radiated to infinity, assuming v/c ≪ 1. Here v is the velocity of the particle. We find that, when a black hole is rotating, the black hole absorption appear at O((v/c)5) beyond the Newtonian-quadrapole formula. These effects become more important as the mass of the black hole becomes larger. We also found that the black hole absorption is more important when a particle moves to the same direction of the black hole rotation. All the details of this paper is presented in Tagoshi et al. (1997).

The black hole symphony: probing new physics using gravitational waves

2008 ◽  
Vol 366 (1884) ◽  
pp. 4365-4379 ◽  
Author(s):  
Jonathan R Gair
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
Direct Detection ◽  
New Physics ◽  
Relativity Theory ◽  
New Generation ◽  
Laser Interferometers ◽  
Near Future ◽  
First Time ◽  
The Universe

The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics.

scholarly journals Pulsar Timing Arrays: Status and Techniques

2012 ◽  
Vol 8 (S291) ◽  
pp. 165-170 ◽  
Author(s):  
George Hobbs
Keyword(s):  
Solar System ◽  
Gravitational Waves ◽  
Quality Data ◽  
Data Sets ◽  
High Quality ◽  
High Quality Data ◽  
Pulsar Timing ◽  
Time Standard ◽  
Near Future

AbstractThree pulsar timing arrays are now producing high quality data sets. As reviewed in this paper, these data sets are been processed to 1) develop a pulsar-based time standard, 2) search for errors in the solar system planetary ephemeris and 3) detect gravitational waves. It is expected that the data sets will significantly improve in the near future by combining existing observations and by using new telescopes.

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