294 research outputs found
Deep Einstein@Home All-sky Search for Continuous Gravitational Waves in LIGO O3 Public Data
No full textWe present the results of an all-sky search for continuous gravitational waves in the public LIGO O3 data. The search covers signal frequencies 20.0 Hz ≤ f ≤ 800.0 Hz and a spin-down range down to −2.6 × 10−9 Hz s−1, motivated by detectability studies on synthetic populations of Galactic neutron stars. This search is the most sensitive all-sky search to date in this frequency/spin-down region. The initial search was performed using the first half of the public LIGO O3 data (O3a), utilizing graphical processing units provided in equal parts by the volunteers of the Einstein@Home computing project and by the ATLAS cluster. After a hierarchical follow-up in seven stages, 12 candidates remain. Six are discarded at the eighth stage, by using the remaining O3 LIGO data (O3b). The surviving six can be ascribed to continuous-wave fake signals present in the LIGO data for validation purposes. We recover these fake signals with very high accuracy with our last stage search, which coherently combines all O3 data. Based on our results, we set upper limits on the gravitational-wave amplitude h 0 and translate these into upper limits on the neutron star ellipticity and on the r-mode amplitude. The most stringent upper limits are at 203 Hz, with h 0 = 8.1 × 10−26 at the 90% confidence level. Our results exclude isolated neutron stars rotating faster than 5 ms with ellipticities greater than 5 × 10 − 8 d 100 pc within a distance d from Earth and r-mode amplitudes α ≥ 10 − 5 d 100 pc for neutron stars spinning faster than 150 Hz
Einstein@Home All-sky “Bucket” Search for Continuous Gravitational Waves in LIGO O3a Public Data
No full textWe conduct an all-sky search for continuous gravitational waves using LIGO O3 public data from the Hanford and Livingston detectors. We search for nearly-monochromatic signals with frequencies and spin-down . We deploy this search on the Einstein@Home volunteer-computing project and on three super computer clusters; the Atlas supercomputer at the Max Planck Institute for Gravitational Physics, and the two high performance computing systems Raven and Viper at the Max Planck Computing and Data Facility. Our results are consistent with a non-detection. We set upper limits on the gravitational wave amplitude , and translate these to upper limits on the neutron star ellipticity and on the r-mode amplitude. The most stringent upper limits are at 173 Hz with , at the 90% confidence level
Deep Einstein@Home Search for Continuous Gravitational Waves from the Central Compact Objects in the Supernova Remnants Vela Jr. and G347.3-0.5 Using LIGO Public Data
No full textWe perform a search for continuous nearly monochromatic gravitational waves from the central compact objects associated with the supernova remnants Vela Jr. and G347.3. Over 10 ^18 different waveforms are considered, covering signal frequencies between 20 and 1300 Hz (20 and 400 Hz) for G347.3-0.5 (Vela Jr.) and a very broad range of frequency derivatives. The data set used for this first search is from the second observing run of LIGO (O2). Thousands of volunteers donating compute cycles through the computing project Einstein@Home have made this endeavor possible. Following the Einstein@Home search, we perform multistage follow-ups of over 5 million waveforms. The threshold for selecting candidates from the Einstein@Home search is such that, after the multistage follow-up, we do not expect any surviving candidate due to noise. The very last stage uses a different data set, namely, the LIGO O3 data. We find no significant signal candidate for either targets. Based on this null result, for G347.3-0.5, we set the most constraining upper limits to date on the amplitude of gravitational-wave signals, corresponding to deformations below 10 ^−6 in a large part of the search band. At the frequency of best strain sensitivity, near 161 Hz, we set 90% confidence upper limits on the gravitational-wave intrinsic amplitude of . Over most of the frequency range, our upper limits are a factor of 10 smaller than the indirect age-based upper limit. For Vela Jr., near 163 Hz, we set . Over most of the frequency range, our upper limits are a factor of 15 smaller than the indirect age-based upper limit. The Vela Jr. upper limits presented here are slightly less constraining than the most recent upper limits of R. Abbott et al., but they apply to a broader set of signals
Deep Einstein@Home all-sky search for continuous gravitational waves in LIGO O3 public data
No full textWe present the results of an all-sky search for continuous gravitational
waves in the public LIGO O3 data. The search covers signal frequencies Hz
Hz and a spin-down range down to Hz
s1, motivated by detectability studies on synthetic populations of
Galactic neutron stars. This search is the most sensitive all-sky search to
date in this frequency/spin-down region. The initial search was performed using
the first half of the public LIGO O3 data (O3a), utilizing Graphical Processing
Units provided in equal parts by the volunteers of the Einstein@Home computing
project and by the ATLAS cluster. After a hierarchical follow-up in seven
stages, 12 candidates remain. Six are discarded at the eighth stage, by using
the remaining O3 LIGO data (O3b). The surviving six can be ascribed to
continuous-wave fake signals present in the LIGO data for validation purposes.
We recover these fake signals with very high accuracy with our last stage
search, which coherently combines all O3 data. Based on our results, we set
upper limits on the gravitational wave amplitude , and translate these in
upper limits on the neutron star ellipticity and on the -mode amplitude. The
most stringent upper limits are at Hz, with at
the 90% confidence level. Our results exclude neutron stars rotating faster
than ms with ellipticities greater than within a distance from Earth and
-mode amplitudes for neutron stars spinning faster than
Hz.Comment: Accepted for publication in The Astrophysical Journal on 31 May 2023.
13 pages, 10 figures, 3 table
Results from an Einstein@Home search for continuous gravitational waves from Cassiopeia A and Vela Jr. using LIGO O2 data
No full textWe conduct two searches for continuous, nearly monochromatic gravitationalwaves originating from the central compact objects in the supernova remnantsCassiopeia A and Vela Jr. using public LIGO data. The search for Cassiopeia Atargets signal frequencies between 20 Hz and 400 Hz; the Vela Jr. searchbetween 400 Hz and 1700 Hz, and both investigate the broadest set of waveformsever considered with highly sensitive deterministic search methods. Above 1500Hz the Vela Jr. search is the most sensitive carried out thus far, improving onprevious results by over 300\%. Above 976 Hz these results improve on existingones by 50\%. In all we investigate over waveforms, leveraging thecomputational power donated by thousands of Einstein@Home volunteers. Weperform a 4-stage follow-up on more than 6 million waveforms. None of theconsidered waveforms survives the follow-up scrutiny, indicating no significatedetection candidate. Our null results constrain the maximum amplitude ofcontinuous signals as a function of signal frequency from the targets. The moststringent 90\% confidence upper limit for Cas A is near 200 Hz, and for Vela Jr. it is near 400 Hz. Translated into upper limits on the ellipticityand r-mode amplitude, our results probe physically interesting regions: forexample the ellipticity of Vela Jr. is constrained to be smaller than across the frequency band, with a tighter constraint of less than at the highest frequencies.<br
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