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Cosmological constraints on the very low frequency gravitational-wave background

Seto, Naoki and Cooray, Asantha (2006) Cosmological constraints on the very low frequency gravitational-wave background. Physical Review D, 73 (2). Art. No. 023005. ISSN 2470-0010. doi:10.1103/PhysRevD.73.023005.

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The curl modes of cosmic microwave background polarization allow one to indirectly constrain the primordial background of gravitational waves with frequencies around 10^(-18) to 10^(-16) Hz. The proposed high precision timing observations of a large sample of millisecond pulsars with the pulsar timing array or with the square kilometer array can either detect or constrain the stochastic gravitational-wave background at frequencies greater than roughly 0.1 yr^(-1). While existing techniques are limited to either observe or constrain the gravitational-wave background across six or more orders of magnitude between 10^(-16) and 10^(-10) Hz, we suggest that the anisotropy pattern of time variation of the redshift related to a sample of high-redshift objects can be used to study the background around a frequency of 10^(-12) Hz. Useful observations to detect an anisotropy signal in the global redshift change include spectroscopic observations of the Ly-alpha forest in absorption towards a sample of quasars, redshifted 21 cm line observations either in absorption or emission towards a sample of neutral HI regions before or during reionization, and high-frequency (0.1 to 1 Hz) gravitational-wave analysis of a sample of neutron star-neutron star binaries detected with gravitational-wave instruments such as the Decihertz Interferometer Gravitational Wave Observatory (DECIGO). For reasonable observations expected in the future involving extragalactic sources, we find limits at the level of Omega(GW)< 10^(-6) at a frequency around 10^(-12) Hz while the ultimate limit is likely to be around Omega(GW)< 10^(-11). On the other hand, if there is a background of gravitational waves at 10^(-12) Hz with an amplitude larger than this limit, its presence will be visible as a measurable anisotropy in the time-evolving redshift of extragalactic sources.

Item Type:Article
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URLURL TypeDescription
Cooray, Asantha0000-0002-3892-0190
Additional Information:© 2006 The American Physical Society. Received 2 February 2005; published 20 January 2006. This work has been supported by NASA Grant No. NNG04GK98G and the Japan Society for the Promotion of Science.
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Subject Keywords:cosmology; gravitational waves; radiofrequency cosmic radiation; pulsars; red shift; circumstellar matter; infrared sources (astronomical); quasars; H I regions; neutron stars; binary stars
Issue or Number:2
Record Number:CaltechAUTHORS:SETprd06a
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3685
Deposited By: Tony Diaz
Deposited On:29 Jun 2006
Last Modified:08 Nov 2021 20:11

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