scholarly journals MULTIPLE IMAGING BY GRAVITATIONAL WAVES

1998 ◽  
Vol 07 (03) ◽  
pp. 409-429 ◽  
Author(s):  
VALERIO FARAONI
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gravitational Lenses ◽  
Multiple Imaging ◽  
Gravitational Wave Background

Gravitational waves act like lenses for the light propagating through them. This phenomenon is described using the vector formalism employed for ordinary gravitational lenses, which was proved to be applicable also to a nonstationary spacetime, with the appropriate modifications. In order to have multiple imaging an approximate condition analogous to that for ordinary gravitational lenses must be satisfied. Certain astrophysical sources of gravitational waves satisfy this condition, while the gravitational wave background, on average, does not. Multiple imaging by gravitational waves is, in principle, possible, but the probability of observing such a phenomenon is extremely low.

scholarly journals PULSAR TIMING ARRAYS

2013 ◽  
Vol 22 (01) ◽  
pp. 1341008 ◽  
Author(s):  
BHAL CHANDRA JOSHI
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Low Frequency ◽  
Radio Pulsars ◽  
Very Low Frequency ◽  
Pulsar Timing ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array ◽  
Current Operating

In the last decade, the use of an ensemble of radio pulsars to constrain the characteristic strain caused by a stochastic gravitational wave background has advanced the cause of detection of very low frequency gravitational waves (GWs) significantly. This electromagnetic means of GW detection, called Pulsar Timing Array (PTA), is reviewed in this paper. The principle of operation of PTA, the current operating PTAs and their status are presented along with a discussion of the main challenges in the detection of GWs using PTA.

Review of the possible role of self-ordering scalar fields in production of a stochastic background of gravitational waves

2015 ◽  
Vol 24 (04) ◽  
pp. 1541005
Author(s):  
James B. Dent
Keyword(s):  
Phase Transition ◽  
Scalar Field ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Scalar Fields ◽  
Inflationary Cosmology ◽  
Tensor Power ◽  
Stochastic Background ◽  
Gravitational Wave Background

A primordial gravitational wave background is a hallmark of inflationary cosmology. The recent announcement made by the BICEP2 collaboration of a possible measurement of B-mode polarization of the CMB on degree scales has produced an abundance of ideas and speculations on how such a signal constrains the inflationary paradigm, or possible alternative mechanisms of gravitational wave production. Here the possibility of a contribution to the gravitational wave background from the relaxation of a scalar field after a global phase transition is reviewed. The general contribution to the overall power is shown, and it is then demonstrated that if the BICEP2 result were to hold, this mechanism could at best produce a very small fraction of the measured tensor power.

scholarly journals Principles of Gravitational-Wave Detection with Pulsar Timing Arrays

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2418
Author(s):  
Michele Maiorano ◽  
Francesco De Paolis ◽  
Achille A. Nucita
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Low Frequency ◽  
Black Hole Binaries ◽  
Pulsar Timing ◽  
Time Correlations ◽  
Array Detection ◽  
Square Kilometer Array ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array

Pulsar timing uses the highly stable pulsar spin period to investigate many astrophysical topics. In particular, pulsar timing arrays make use of a set of extremely well-timed pulsars and their time correlations as a challenging detector of gravitational waves. It turns out that pulsar timing arrays are particularly sensitive to ultra-low-frequency gravitational waves, which makes them complementary to other gravitational-wave detectors. Here, we summarize the basics, focusing especially on supermassive black-hole binaries and cosmic strings, which have the potential to form a stochastic gravitational-wave background in the pulsar timing array detection band, and the scientific goals on this challenging topic. We also briefly outline the recent interesting results of the main pulsar timing array collaborations, which have found strong evidence of a common-spectrum process compatible with a stochastic gravitational-wave background and mention some new perspectives that are particularly interesting in view of the forthcoming radio observatories such as the Five hundred-meter Aperture Spherical Telescope, the MeerKAT telescope, and the Square Kilometer Array.

THE POLARIZATION OF THE COSMIC MICROWAVE BACKGROUND DUE TO PRIMORDIAL GRAVITATIONAL WAVES

2006 ◽  
Vol 21 (12) ◽  
pp. 2459-2479 ◽  
Author(s):  
BRIAN G. KEATING ◽  
ALEXANDER G. POLNAREV ◽  
NATHAN J. MILLER ◽  
DEEPAK BASKARAN
Keyword(s):  
Cosmic Microwave Background ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Microwave Background ◽  
Primordial Gravitational Waves ◽  
Cmb Polarization ◽  
Cosmological Inflation ◽  
Gravitational Wave Background ◽  
Review Current ◽  
Rule Out

We review current observational constraints on the polarization of the Cosmic Microwave Background (CMB), with a particular emphasis on detecting the signature of primordial gravitational waves. We present an analytic solution to the Polanarev approximation for CMB polarization produced by primordial gravitational waves. This simplifies the calculation of the curl, or B-mode power spectrum associated with gravitational waves during the epoch of cosmological inflation. We compare our analytic method to existing numerical methods and also make predictions for the sensitivity of upcoming CMB polarization observations to the inflationary gravitational wave background. We show that upcoming experiments should be able either detect the relic gravitational wave background or completely rule out whole classes of inflationary models.

scholarly journals Constraining the nanohertz gravitational wave background with the Parkes Pulsar Timing Array

2012 ◽  
Vol 8 (S291) ◽  
pp. 177-177
Author(s):  
Ryan Shannon
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Pulsar Timing ◽  
The Galaxy ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array ◽  
The Universe

AbstractThe direct detection of gravitational waves will usher in a new era of astrophysics, enabling the study of regions of the universe opaque to electromagnetic radiation or electromagnetically quiet. An ensemble of pulsars (referred to as a pulsar timing array) provides a set of clocks distributed across the Galaxy sensitive to gravitational waves with periods on the order of five years (frequencies of many nanohertz). Plausible source of gravitational waves in this frequency band include massive black hole binaries in the throes of mergers and oscillating cosmic strings. The stochastic gravitational wave background, the sum of gravitational waves emitted throughout the universe, is the most likely signal to be detected by a pulsar timing array.While the detection of gravitational waves will be a milestone in pulsar astronomy, a constraining limit on the strength of the gravitational wave background can be used to constrain cosmological models and early Universe physics. Here we present a new algorithm that can be used to constrain the strength of the GWB with a pulsar timing array. We then apply this technique to Parkes Pulsar Timing Array observations and place a new limit on the strength of the GWB. We conclude by discussing the astrophysical implications of this limit and the prospects for detecting gravitational waves with pulsars.

scholarly journals Gravitons to photons — Attenuation of gravitational waves

2015 ◽  
Vol 24 (12) ◽  
pp. 1544017 ◽  
Author(s):  
Preston Jones ◽  
Douglas Singleton
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Electron Scattering ◽  
Muon Decay ◽  
Detector Response ◽  
Level System ◽  
Three Body ◽  
Gravitational Wave Background

In this essay, we examine the response of an Unruh–DeWitt (UD) detector (a quantum two-level system) to a gravitational wave background. The spectrum of the UD detector is of the same form as some scattering processes or three body decays such as muon-electron scattering or muon decay. Based on this similarity, we propose that the UD detector response implies a “decay” or attenuation of gravitons, [Formula: see text], into photons, [Formula: see text], via [Formula: see text] or [Formula: see text]. Over large distances such a decay/attenuation may have consequences in regard to the detection of gravitational waves.

scholarly journals The Stochastic Gravitational Wave Background Generated by Cosmic String Networks

2014 ◽  
Vol 10 (S306) ◽  
pp. 391-393
Author(s):  
L. Sousa ◽  
P. P. Avelino
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Recent Work ◽  
Cosmic String ◽  
Cosmological Evolution ◽  
Analytical Tools ◽  
String Networks ◽  
Gravitational Wave Background

AbstractCosmic string interactions often result in the formation of cosmic string loops that detach from the long string network and radiate their energy in the form of gravitational waves. Loop production occurs copiously throughout the cosmological evolution of a cosmic string network and the superimposition of their emissions gives rise to a stochastic gravitational In this essay, we briefly review our recent work on the stochastic gravitational wave background generated by cosmic string networks and introduce a set of numerical and analytical tools for the computation of this background.

scholarly journals A CMB B-mode Search with Three Years of BICEP Observations

2012 ◽  
Vol 8 (S288) ◽  
pp. 61-67
Author(s):  
Colin Bischoff ◽  
Keyword(s):  
Cosmic Microwave Background ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Final Analysis ◽  
Integration Time ◽  
South Pole ◽  
Microwave Background ◽  
Promising Technique ◽  
Primordial Gravitational Waves ◽  
Gravitational Wave Background

AbstractThe search for B-mode, or curl-type, polarization in the Cosmic Microwave Background is the most promising technique to constrain or detect primordial gravitational waves predicted by the theory of inflation. The Bicep telescope, which observed from the South Pole for three years from 2006 through 2008, is the first experiment specifically designed to target this signal. We review the observational motivations for inflation, the advantages of B-mode observations as a technique for detecting the gravitational wave background, and the design features of Bicep that optimize it for this search. The final analysis of all three seasons of Bicep data is in progress, representing a 50% increase in integration time compared to the result from Chiang et al. (2010). A preview of the three year result includes E-mode and B-mode maps, as well as the projected constraint on r, the tensor-to-scalar ratio.

scholarly journals LIMITS ON THE STOCHASTIC GRAVITATIONAL WAVE BACKGROUND FROM THE NORTH AMERICAN NANOHERTZ OBSERVATORY FOR GRAVITATIONAL WAVES

2012 ◽  
Vol 762 (2) ◽  
pp. 94 ◽  
Author(s):  
P. B. Demorest ◽  
R. D. Ferdman ◽  
M. E. Gonzalez ◽  
D. Nice ◽  
S. Ransom ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
North American ◽  
The North ◽  
Gravitational Wave Background

scholarly journals Multifrequency Gravitational Wave Background From Continuous Sources

2021 ◽  
Author(s):  
C Sivaram ◽  
Arun Kenath
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Mass Range ◽  
Compact Objects ◽  
Compact Binary ◽  
Transient Events ◽  
Stellar Interiors ◽  
Gravitational Wave Background ◽  
Hubble Time ◽  
Thermal Background

Gravitational waves have been detected in the past few years from several transient events such as merging stellar mass black holes, binary neutron stars, etc. These waves have frequencies in a band ranging from a few hundred hertz to around a kilohertz to which LIGO type instruments are sensitive. LISA would be sensitive to much lower range of frequencies from SMBH mergers. Apart from these cataclysmic burst events, there are innumerable sources of radiation which are continuously emitting gravitational waves of all frequencies. These include a whole mass range of compact binary and isolated compact objects as well as close planetary stellar entities. In this work, quantitative estimates are made of the gravitational wave background produced in typical frequency ranges from such sources emitting over a Hubble time and the fluctuations in the h values measured in the usual devices. Also estimates are made of the high frequency thermal background gravitational radiation from hot stellar interiors and newly formed compact objects.

Sign in / Sign up

Export Citation Format

Share Document