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General Relativity and Quantum Cosmology, gr-qc,High Energy Physics - Phenomenology, hep-ph
Abstract:
We conduct two searches for continuous, nearly monochromatic gravitational
waves originating from the central compact objects in the supernova remnants
Cassiopeia A and Vela Jr. using public LIGO data. The search for Cassiopeia A
targets signal frequencies between 20 Hz and 400 Hz; the Vela Jr. search
between 400 Hz and 1700 Hz, and both investigate the broadest set of waveforms
ever considered with highly sensitive deterministic search methods. Above 1500
Hz the Vela Jr. search is the most sensitive carried out thus far, improving on
previous results by over 300\%. Above 976 Hz these results improve on existing
ones by 50\%. In all we investigate over $10^{18}$ waveforms, leveraging the
computational power donated by thousands of Einstein@Home volunteers. We
perform a 4-stage follow-up on more than 6 million waveforms. None of the
considered waveforms survives the follow-up scrutiny, indicating no significate
detection candidate. Our null results constrain the maximum amplitude of
continuous signals as a function of signal frequency from the targets. The most
stringent 90\% confidence upper limit for Cas A is $h_0^{90 \%}\approx
7.3\times10^{-26}$ near 200 Hz, and for Vela Jr. it is $h_0^{90 \%}\approx
8.9\times10^{-26}$ near 400 Hz. Translated into upper limits on the ellipticity
and r-mode amplitude, our results probe physically interesting regions: for
example the ellipticity of Vela Jr. is constrained to be smaller than $10^{-7}$
across the frequency band, with a tighter constraint of less than
$2\times10^{-8}$ at the highest frequencies.
