Search for continuous gravitational wave emission from the Milky Way center in O3 LIGO-Virgo data

Abstract

We present a directed search for continuous gravitational wave (CW) signals emitted by spinning neutron stars located in the inner parsecs of the Galactic Center (GC). Compelling evidence for the presence of a numerous population of neutron stars has been reported in the literature, turning this region into a very interesting place to look for CWs. In this search, data from the full O3 LIGO-Virgo run in the detector frequency band ½10; 2000 Hz have been used. No significant detection was found and 95% confidence level upper limits on the signal strain amplitude were computed, over the full search band, with the deepest limit of about 7.6 × 10 −26 at ≃142 Hz. These results are significantly more constraining than those reported in previous searches. We use these limits to put constraints on the fiducial neutron star ellipticity and r-mode amplitude. These limits can be also translated into constraints in the black hole mass-boson mass plane for a hypothetical population of boson clouds around spinning black holes located in the GC.

Prospects for the Observation of Continuous Gravitational Waves from Spinning Neutron Stars Lensed by the Galactic Supermassive Black Hole

“…These estimates are consistent with the nondetection of CGWs by the directed searches toward the galactic center using LIGO-Virgo data from the third observing run (Abbott et al 2022). Using the spatial and frequency distribution models that we employed to study the detectability of lensed signals, we estimate the detection probability of (all) CGWs to be ∼0%-2% with ò = 10 −7 and a coherent integration time of 1 yr. 10 For the coherent integration times of a few hours employed in Abbott et al (2022), the expected detection probability is almost zero.…”

“…We assume an ellipticity of 10 −7 , which is one order of magnitude smaller than the best upper limits obtained from a directed search for NSs in the galactic center, for a fiducial moment of inertia of 10 38 kg m 2 (Abbott et al 2022). Spin frequencies are drawn from the spin distribution of known pulsars (Manchester et al 2005).…”

Probing the pulsar explanation of the Galactic-Center GeV excess using continuous gravitational-wave searches

“…In this study, we apply the results obtained in the Frequency-Hough all-sky search to constrain the number of millisecond pulsars at the Galactic Center. We note that this search and the one that specifically targets a single sky pixel that completely covers the Galactic Center [61] are complementary to each other, and we will comment on the future optimization later. The Galactic-Center search can obtain a better sensitivity than the all-sky one, since it only looks at one pixel, significantly reducing the computational cost of the search, and can therefore use longer Fourier Transforms to look for quasimonochromatic signals.…”

“…This gives where P (log 10 f ) and P (log 10 ) are the probability density functions for gravitational wave frequency and ellipticity, respectively, and f has units of Hz. Also, we take f min = 120 Hz and f max = 2000 Hz, which is the range of frequencies analyzed in the all-sky search [61] with a cutoff at f rot = 60 Hz to ensure we are targeting millisecond pulsars. This corresponds to a millisecond pulsar rotational frequency range of f rot = [60, 1000] Hz.…”

Accumulation of Elastic Strain toward Crustal Fracture in Magnetized Neutron Stars

“…Therefore, the calculation of the maximum size of these mountains is the key to the detection of gravitational waves and has been discussed in several theoretical studies (Ushomirsky et al 2000;Payne & Melatos 2004;Haskell et al 2006;Gittins et al 2021). Gravitational-wave observation provides valuable information (Abbott et al 2021a(Abbott et al , 2021b(Abbott et al , 2022, for recent upper limit); thus, by continuously improving the sensitivity of the LIGO-Virgo-KAGRA detectors, the physics relevant to the phenomenon may be explored.…”