Deep Einstein@Home All-sky Search for Continuous Gravitational Waves in LIGO O3 Public Data

Abstract

We 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.

Improved Upper Limits on Gravitational-wave Emission from NS 1987A in SNR 1987A

“…and is greater than the maximum value covered by the all-sky surveys such as Steltner et al (2023). It does not include some of the more extreme ranges recently proposed by Morales & Horowitz (2023), which is more appropriate for older stars.…”

“…Even with a narrow parameter space, Sun et al (2016) did not achieve upper limits comparable to h . 0 age Recent all-sky surveys for continuous GWs such as Steltner et al (2023) do beat that limit in the direction of NS 1987A but do not cover spin-down ranges physically consistent with NS 1987A. Wette et al (2008) derived h 0 age for mass-quadrupole GW emission ("mountains"), and Owen (2010) extended it to current-quadrupole GW emission from r-modes.…”

Open Data from the Third Observing Run of LIGO, Virgo, KAGRA, and GEO

“…310 These analyses confirm, complement, and extend the results published by the LVK Collaboration. They cover a wide range of topics, including searches for GW signals (Nitz & Wang 2022;Olsen et al 2022;Nitz et al 2023;Steltner et al 2023;Whelan et al 2023), studies of compact binary populations (see, e.g., Roulet et al 2021;Callister & Farr 2023;Périgois et al 2023), tests of general relativity (see, e.g., Capano et al 2021Capano et al , 2022Estellés et al 2022;Lyu et al 2022;Wang et al 2022), or methodological contributions (see, e.g., Davis et al 2022), demonstrating the broad impact on the scientific community of the GW data releases.…”

Continuous Gravitational Waves from Galactic Neutron Stars: Demography, Detectability, and Prospects

“…In this case, assumptions on the expected signal population define the surveyed parameter space. Extensive searches are carried out (for a sample of recent results, see Dergachev & Papa 2021;Covas et al 2022;Dergachev & Papa 2023;Abbott et al 2021cSteltner et al 2023), which have translated the no-detection results into constraints on the physical parameters of the subpopulation investigated so far.…”

“…Average Number of Sources Detectable by the ET and CE with Searches Comparable with the Advanced LIGO Data Searches(Abbott et al 2022e;Steltner et al 2023) The last column is obtained considering the total detectable sources by either the ET or CE, and similarly to Table3, represents the fraction of detectable sources over the total number of sources in-band for each model (third column of Table2).…”