Modelbased Crosscorrelation Search for Gravitational Waves from the Lowmass XRay Binary Scorpius X1 in LIGO O3 Data
Abstract
We present the results of a modelbased search for continuous gravitational waves from the lowmass Xray binary Scorpius X1 using LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo. This is a semicoherent search that uses details of the signal model to coherently combine data separated by less than a specified coherence time, which can be adjusted to balance sensitivity with computing cost. The search covered a range of gravitationalwave frequencies from 25 to 1600 Hz, as well as ranges in orbital speed, frequency, and phase determined from observational constraints. No significant detection candidates were found, and upper limits were set as a function of frequency. The most stringent limits, between 100 and 200 Hz, correspond to an amplitude h _{0} of about 10^{25} when marginalized isotropically over the unknown inclination angle of the neutron star's rotation axis, or less than 4 × 10^{26} assuming the optimal orientation. The sensitivity of this search is now probing amplitudes predicted by models of torque balance equilibrium. For the usual conservative model assuming accretion at the surface of the neutron star, our isotropically marginalized upper limits are close to the predicted amplitude from about 70 to 100 Hz; the limits assuming that the neutron star spin is aligned with the most likely orbital angular momentum are below the conservative torque balance predictions from 40 to 200 Hz. Assuming a broader range of accretion models, our direct limits on gravitationalwave amplitude delve into the relevant parameter space over a wide range of frequencies, to 500 Hz or more.
 Publication:

The Astrophysical Journal
 Pub Date:
 December 2022
 DOI:
 10.3847/20418213/aca1b0
 arXiv:
 arXiv:2209.02863
 Bibcode:
 2022ApJ...941L..30A
 Keywords:

 Gravitational waves;
 Gravitational wave astronomy;
 Lowmass xray binary stars;
 Neutron stars;
 678;
 675;
 939;
 1108;
 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 19 pages, Open Access Journal PDF