Directed search for gravitational waves from Scorpius X-1 with initial LIGO data
Source
Physical Review D Particles Fields Gravitation and Cosmology
ISSN
15507998
Date Issued
2015-03-26
Author(s)
Aasi, J.
Abbott, B. P.
Abbott, R.
Abbott, T.
Abernathy, M. R.
Acernese, F.
Ackley, K.
Adams, C.
Adams, T.
Addesso, P.
Adhikari, R. X.
Adya, V.
Affeldt, C.
Agathos, M.
Agatsuma, K.
Aggarwal, N.
Aguiar, O. D.
Ain, A.
Ajith, P.
Alemic, A.
Allen, B.
Allocca, A.
Amariutei, D.
Anderson, S. B.
Anderson, W. G.
Arai, K.
Araya, M. C.
Arceneaux, C.
Areeda, J. S.
Arnaud, N.
Ashton, G.
Ast, S.
Aston, S. M.
Astone, P.
Aufmuth, P.
Aulbert, C.
Aylott, B. E.
Babak, S.
Baker, P. T.
Baldaccini, F.
Ballardin, G.
Ballmer, S. W.
Barayoga, J. C.
Barbet, M.
Barclay, S.
Barish, B. C.
Barker, D.
Barone, F.
Barr, B.
Barsotti, L.
Barsuglia, M.
Bartlett, J.
Barton, M. A.
Bartos, I.
Bassiri, R.
Basti, A.
Batch, J. C.
Bauer, Th S.
Baune, C.
Bavigadda, V.
Behnke, B.
Bejger, M.
Belczynski, C.
Bell, A. S.
Bell, C.
Benacquista, M.
Bergman, J.
Bergmann, G.
Berry, C. P.L.
Bersanetti, D.
Bertolini, A.
Betzwieser, J.
Bhagwat, S.
Bhandare, R.
Bilenko, I. A.
Billingsley, G.
Birch, J.
Biscans, S.
Bitossi, M.
Biwer, C.
Bizouard, M. A.
Blackburn, J. K.
Blackburn, L.
Blair, C. D.
Blair, D.
Bloemen, S.
Bock, O.
Bodiya, T. P.
Boer, M.
Bogaert, G.
Bojtos, P.
Bond, C.
Bondu, F.
Bonelli, L.
Bonnand, R.
Bork, R.
Born, M.
Boschi, V.
Bose, Sukanta
Bradaschia, C.
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.