Directed search for gravitational waves from Scorpius X-1 with initial LIGO data
Abstract
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.
- Publication:
-
Physical Review D
- Pub Date:
- March 2015
- DOI:
- 10.1103/PhysRevD.91.062008
- arXiv:
- arXiv:1412.0605
- Bibcode:
- 2015PhRvD..91f2008A
- Keywords:
-
- 95.85.Sz;
- 97.60.Jd;
- 97.80.Jp;
- Gravitational radiation magnetic fields and other observations;
- Neutron stars;
- X-ray binaries;
- General Relativity and Quantum Cosmology;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 19 pages, 8 figures