298 research outputs found
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data
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\u27s 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
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-Based Cross-Correlation Search in Advanced LIGO Data
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 x 10-25 marginalized over the unknown inclination angle of the neutron star\u27s spin, and 8.0 x 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
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-Based Cross-Correlation Search in Advanced LIGO Data
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–, 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 , with comparable limits set across the most sensitive frequency range from 100 to . At this frequency, the 95% upper limit on the signal amplitude h 0 is marginalized over the unknown inclination angle of the neutron star\u27s spin, and 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 , 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
Search for gravitational waves from Scorpius X-1 in LIGO O3 data with corrected orbital ephemeris
Improved observational constraints on the orbital parameters of the low-mass X-ray binary Scorpius X-1 were recently published in Killestein et al. In the process, errors were corrected in previous orbital ephemerides, which have been used in searches for continuous gravitational waves from Sco X-1 using data from the Advanced LIGO detectors. We present the results of a reanalysis of LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo using a model-based cross-correlation search. The corrected region of parameter space, which was not covered by previous searches, was about 1/3 as large as the region searched in the original O3 analysis, reducing the required computing time. We have confirmed that no detectable signal is present over a range of gravitational-wave frequencies from 25 to 1600 Hz, analogous to the null result of Abbott et al. Our search sensitivity is comparable to that of Abbott et al., who set upper limits corresponding, between 100 and 200 Hz, to an amplitude h0 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
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data
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 x 10^(-25) marginalized over the unknown inclination angle of the neutron star's spin, and 8.0 x 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
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data
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–, 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 , with comparable limits set across the most sensitive frequency range from 100 to . At this frequency, the 95% upper limit on the signal amplitude h 0 is marginalized over the unknown inclination angle of the neutron star's spin, and 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 , 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
Search for Gravitational Waves from Scorpius X-1 in LIGO O3 Data With Corrected Orbital Ephemeris
Improved observational constraints on the orbital parameters of the low-mass
X-ray binary Scorpius~X-1 were recently published in Killestein et al (2023).
In the process, errors were corrected in previous orbital ephemerides, which
have been used in searches for continuous gravitational waves from Sco~X-1
using data from the Advanced LIGO detectors. We present the results of a
re-analysis of LIGO detector data from the third observing run of Advanced LIGO
and Advanced Virgo using a model-based cross-correlation search. The corrected
region of parameter space, which was not covered by previous searches, was
about 1/3 as large as the region searched in the original O3 analysis, reducing
the required computing time. We have confirmed that no detectable signal is
present over a range of gravitational-wave frequencies from to
, analogous to the null result of Abbott et al (2022). Our
search sensitivity is comparable to that of Abbott et al (2022), who set upper
limits corresponding, between and , to an
amplitude of about when marginalized isotropically over the
unknown inclination angle of the neutron star's rotation axis, or less than
assuming the optimal orientation.Comment: 8 pages, 3 figures, 2 tables. Typeset with AASTeX 6.3.1. Accepted for
publication in The Astrophysical Journal. arXiv admin note: text overlap with
arXiv:2209.0286
Resampling to accelerate cross-correlation searches for continuous gravitational waves from binary systems
Continuous-wave (CW) gravitational waves (GWs) call for
computationally-intensive methods. Low signal-to-noise ratio signals need
templated searches with long coherent integration times and thus fine
parameter-space resolution. Longer integration increases sensitivity. Low-mass
x-ray binaries (LMXBs) such as Scorpius X-1 (Sco X-1) may emit accretion-driven
CWs at strains reachable by current ground-based observatories. Binary orbital
parameters induce phase modulation. This paper describes how resampling
corrects binary and detector motion, yielding source-frame time series used for
cross-correlation. Compared to the previous, detector-frame, templated
cross-correlation method, used for Sco X-1 on data from the first Advanced LIGO
observing run (O1), resampling is about 20x faster in the costliest,
most-sensitive frequency bands. Speed-up factors depend on integration time and
search setup. The speed could be reinvested into longer integration with a
forecast sensitivity gain, 20 to 125 Hz median, of approximately 51%, or from
20 to 250 Hz, 11%, given the same per-band cost and setup. This paper's timing
model enables future setup optimization. Resampling scales well with longer
integration, and at 10x unoptimized cost could reach respectively 2.83x and
2.75x median sensitivities, limited by spin-wandering. Then an O1 search could
yield a marginalized-polarization upper limit reaching torque-balance at 100
Hz. Frequencies from 40 to 140 Hz might be probed in equal observing time with
2x improved detectors.Comment: 28 pages, 7 figures, 3 table
Gravitational waves from Sco X-1: A comparison of search methods and prospects for detection with advanced detectors
The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most
luminous source of continuous gravitational-wave radiation for interferometers
such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be
sustained by active accretion of matter from its binary companion. With the
Advanced Detector Era fast approaching, work is underway to develop an array of
robust tools for maximizing the science and detection potential of Sco X-1. We
describe the plans and progress of a project designed to compare the numerous
independent search algorithms currently available. We employ a mock-data
challenge in which the search pipelines are tested for their relative
proficiencies in parameter estimation, computational efficiency, robust- ness,
and most importantly, search sensitivity. The mock-data challenge data contains
an ensemble of 50 Scorpius X-1 (Sco X-1) type signals, simulated within a
frequency band of 50-1500 Hz. Simulated detector noise was generated assuming
the expected best strain sensitivity of Advanced LIGO and Advanced VIRGO ( Hz). A distribution of signal amplitudes was then
chosen so as to allow a useful comparison of search methodologies. A factor of
2 in strain separates the quietest detected signal, at
strain, from the torque-balance limit at a spin frequency of 300 Hz, although
this limit could range from (25 Hz) to (750 Hz) depending on the unknown frequency of Sco X-1. With future
improvements to the search algorithms and using advanced detector data, our
expectations for probing below the theoretical torque-balance strain limit are
optimistic.Comment: 33 pages, 11 figure
- …