Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50–550 Hz, and performs an incoherent sum of coherent F -statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and an angle-restricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3 × 10−24 and 8 × 10−25 are reported at 150 Hz for the standard and angle-restricted searches respectively. This proof-of-principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of ∼1.4 for the standard, and 2.3 for the angle-restricted search at the sensitive region of the detector.

Bibliographic Details

Main Authors:	Aasi, J., Abbott, B. P., Abbott, R., Abbott, T., Abernathy, M. R., Acernese, F., Domínguez, Alfredo Eduardo, Maglione, César Germán, Ortega Larcher, Walter Emanuel, Quiroga, Gonzalo Damián, Reula, Oscar Alejandro
Format:	article biblioteca
Language:	eng
Published:	2015
Subjects:	Gravitational waves, Neutron stars, X-ray binaries, General Relativity and Quantum Cosmology, Astrophysics, High Energy Astrophysical Phenomena,
Online Access:	http://hdl.handle.net/11086/29514 https://doi.org/10.1103/PhysRevD.91.062008
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