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 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 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 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.

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