Gravitational wave background from rotating neutron stars

Abstract

The background of gravitational waves produced by the ensemble of rotating neutron stars (which includes pulsars, magnetars and gravitars) is investigated. A formula for Ω(f) (commonly used to quantify the background) is derived, properly taking into account the time evolution of the systems since their formation until the present day. Moreover, the formula allows one to distinguish the different parts of the background: the unresolvable (which forms a stochastic background) and the resolvable. Several estimations of the background are obtained, for different assumptions on the parameters that characterize neutron stars and their population. In particular, different initial spin period distributions lead to very different results. For one of the models, with slow initial spins, the detection of the background can be rejected. However, other models do predict the detection of the background by the future ground-based gravitational wave detector ET. A robust upper limit for the background of rotating neutron stars is obtained; it does not exceed the detection threshold of two cross-correlated Advanced LIGO interferometers. If gravitars exist and constitute more than a few percent of the neutron star population, then they produce an unresolvable background that could be detected by ET. Under the most reasonable assumptions on the parameters characterizing a neutron star, the background is too faint. Previous papers have suggested neutron star models in which large magnetic fields (like the ones that characterize magnetars) induce big deformations in the star, which produce a stronger emission of gravitational radiation. Considering the most optimistic (in terms of the detection of gravitational waves) of these models, an upper limit for the background produced by magnetars is obtained; it could be detected by ET, but not by BBO or DECIGO.

25 pages, 15 figures

References in corpus (12)

• The ATNF Pulsar Catalogue
• LIGO: The Laser Interferometer Gravitational-Wave Observatory
• Physics of Strongly Magnetized Neutron Stars
• Intermediate and Extreme Mass-Ratio Inspirals -- Astrophysics, Science Applications and Detection using LISA
• The Evolution of Stellar Mass and the Implied Star Formation History
• On the Evolutionary History of Stars and their Fossil Mass and Light
• The History of Cosmological Star Formation: Three Independent Approaches and a Critical Test Using the Extragalactic Background Light
• Blandford's Argument: The Strongest Continuous Gravitational Wave Signal
• How rapidly do neutron stars spin at birth? Constraints from archival X-ray observations of extragalactic supernovae
• Detecting a Stochastic Gravitational-Wave Background: The Overlap Reduction Function
• Stochastic Gravitational Wave Background from Neutron Star r-mode Instability Revisited
• Ultrahigh energy cosmic ray acceleration in newly born magnetars and their associated gravitational wave signatures