Title

Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data

Authors

B. P. Abbott, California Institute of Technology
R. Abbott, California Institute of Technology
T. D. Abbott, Louisiana State University
F. Acernese, Università degli Studi di Salerno
K. Ackley, University of Florida
C. Adams, LIGO Livingston
T. Adams, Université Savoie Mont Blanc
P. Addesso, Università degli Studi del Sannio
R. X. Adhikari, California Institute of Technology
V. B. Adya, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
C. Affeldt, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
M. Afrough, University of Mississippi
B. Agarwal, University of Illinois Urbana-Champaign
M. Agathos, University of Cambridge
K. Agatsuma, FOM-Institute of Subatomic Physics - NIKHEF
N. Aggarwal, LIGO, Massachusetts Institute of Technology
O. D. Aguiar, Instituto Nacional de Pesquisas Espaciais
L. Aiello, Gran Sasso Science Institute
A. Ain, Inter-University Centre for Astronomy and Astrophysics India
P. Ajith, Tata Institute of Fundamental Research, Mumbai
B. Allen, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
G. Allen, University of Illinois Urbana-Champaign
A. Allocca, Università di Pisa
P. A. Altin, The Australian National University
A. Amato, IN2P3 Institut National de Physique Nucleaire et de Physique des Particules
A. Ananyeva, California Institute of Technology
S. B. Anderson, California Institute of Technology
W. G. Anderson, University of Wisconsin-Milwaukee
S. Antier, Laboratoire de l'Accélérateur Linéaire
S. Appert, California Institute of Technology
K. Arai, California Institute of Technology
M. C. Araya, California Institute of Technology
J. S. Areeda, California State University, Fullerton

Document Type

Article

Publication Date

9-20-2017

Abstract

We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using data from the first Advanced LIGO observing run. The search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specified coherence time, which can be adjusted to trade off sensitivity against computational cost. A search was conducted over the frequency range 25-2000 Hz, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates and simulated signal injections. The most stringent upper limit was set at 175 Hz, with comparable limits set across the most sensitive frequency range from 100 to 200 Hz. At this frequency, the 95% upper limit on the signal amplitude h0 is 2.3 × 10-25 marginalized over the unknown inclination angle of the neutron star's spin, and 8.0 × 10-26 assuming the best orientation (which results in circularly polarized gravitational waves). These limits are a factor of 3-4 stronger than those set by other analyses of the same data, and a factor of ∼ 7 stronger than the best upper limits set using data from Initial LIGO science runs. In the vicinity of 100 Hz, the limits are a factor of between 1.2 and 3.5 above the predictions of the torque balance model, depending on the inclination angle; if the most likely inclination angle of 44° is assumed, they are within a factor of 1.7.

Publication Source (Journal or Book title)

Astrophysical Journal

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