J/ApJ/906/L14 LIGO O2; gravitational waves from Scorpius X-1 (Zhang+, 2021)
Search for Continuous Gravitational Waves from Scorpius X-1 in LIGO O2 Data.
Zhang Y., Papa M.A., Krishnan B., Watts A.L.
<Astrophys. J., 906, L14 (2021)>
=2021ApJ...906L..14Z 2021ApJ...906L..14Z
ADC_Keywords: Stars, neutron; Binaries, X-ray; Gravitational wave;
Photometry, millimetric/submm
Keywords: Gravitational waves ; Neutron stars ; Low-mass x-ray binary
stars
Abstract:
We present the results of a search in LIGO O2 public data for
continuous gravitational waves from the neutron star in the low-mass
X-ray binary Scorpius X-1. We search for signals with ∼constant
frequency in the range 40-180Hz. Thanks to the efficiency of our
search pipeline we can use a long coherence time and achieve
unprecedented sensitivity, significantly improving on existing
results. This is the first search that has been able to probe
gravitational wave amplitudes that could balance the accretion torque
at the neutron star radius. Our search excludes emission at this level
between 67.5 and 131.5Hz, for an inclination angle 44°±6°
derived from radio observations, and assuming that the spin axis is
perpendicular to the orbital plane. If the torque arm is ∼26km-a
conservative estimate of the Alfven radius-our results are more
constraining than the indirect limit across the band. This allows us
to exclude certain mass-radius combinations and to place upper limits
on the strength of the star's magnetic field with a different probe
than ever used before. We also correct a mistake that appears in the
literature in the equation that gives the gravitational wave amplitude
at the torque balance and we re-interpret the associated latest
LIGO/Virgo results in light of this.
Description:
We use LIGO O2 open data from the Hanford and Livingston detectors
(LIGO 2019; http://www.gw-openscience.org/O2/) between GPS time
1167984930 (2016 January) and GPS time 1187733514 (2016 August).
Objects:
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RA (2000) DE Designation(s)
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16 19 55.07 -15 38 25.0 Sco X-1 = V* V818 Sco
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 24 280 95% confidence upper limits on the intrinsic
gravitational wave amplitude in half-Hz bands
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See also:
J/ApJ/839/12 : Gravitational waves search from PSR with LIGO (Abbott+, 2017)
J/ApJ/879/10 : 2015-2017 LIGO obs. analysis for 221 pulsars (Abbott+, 2019)
J/ApJ/902/L46 : Gravitational-wave freq. limits PSRJ1653-0158 (Nieder+, 2020)
http://www.gw-openscience.org/O2/ : Gravitational Wave Open Science Center
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 Hz Freq [40/180] Gravitation wave frequency
8- 15 E8.2 --- Amp [7.06e-26/8.56e-25] Gravitation wave amplitude upper
limit (1)
17- 24 E8.2 --- AmpM [1.23e-25/1.49e-24] Marginalized gravitation wave
amplitude upper limit (2)
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Note (1): Inclination angle i=44±6degrees.
Note (2): Inclination angle i arbitrary.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 19-May-2022