TY - JOUR

T1 - Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

AU - Aylott, Benjamin

AU - Berry, Christopher

AU - Bond, Charlotte

AU - Brown, Daniel

AU - Del Pozzo, Walter

AU - Farr, Will

AU - Freise, Andreas

AU - Haster, Carl-Johan

AU - Mandel, Ilya

AU - Miao, Haixing

AU - Middleton, Hannah

AU - Sidery, Trevor

AU - Stevenson, Simon

AU - Vecchio, Alberto

AU - Veitch, John

AU - Vousden, Will

AU - Wang, Haoyu

AU - Wang, Mengyao

AU - LIGO Scientific Collaboration

AU - Virgo Collaboration

PY - 2015/3/26

Y1 - 2015/3/26

N2 - 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.

AB - 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.

U2 - 10.1103/physrevd.91.062008

DO - 10.1103/physrevd.91.062008

M3 - Article

SN - 1550-7998

VL - 91

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

M1 - 062008

ER -