Impact of signal clusters in wide-band searches for continuous gravitational waves

Abstract

In this paper we present a study of some relevant steps of the hierarchical frequency-Hough (FH) pipeline, used within the LIGO and Virgo Collaborations for wide-parameter space searches of continuous gravitational waves (CWs) emitted, for instance, by spinning neutron stars (NSs). Because of their weak expected amplitudes, CWs have not been still detected so far. These steps, namely the spectral estimation, the {\it peakmap} construction and the procedure to select candidates in the FH plane, are critical as they contribute to determine the final search sensitivity. Here, we are interested in investigating their behavior in the (presently quite) extreme case of signal clusters, due to many and strong CW sources, emitting gravitational waves (GWs) within a small (i.e. <1 Hz wide) frequency range. This could happen for some kinds of CW sources detectable by next generation detectors, like LISA, Einstein Telescope and Cosmic Explorer. Moreover, this possibility has been recently raised even for current Earth-based detectors, in some scenarios of CW emission from ultralight boson clouds around stellar mass black holes (BHs). We quantitatively evaluate the robustness of the FH analysis procedure, designed to minimize the loss of single CW signals, under the unusual situation of signal clusters. Results depend mainly on how strong in amplitude and dense in frequency the signals are, and on the range of frequency they cover. We show that indeed a small sensitivity loss may happen in presence of a very high mean signal density affecting a frequency range of the order of one Hertz, while when the signal cluster covers a frequency range of one tenth of Hertz, or less, we may actually have a sensitivity gain. Overall, we demonstrate the FH to be robust even in presence of moderate-to-large signal clusters.

References in corpus (10)

• GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
• Gravitational wave searches for ultralight bosons with LIGO and LISA
• All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO O2 data
• Method for all-sky searches of continuous gravitational wave signals using the frequency-Hough transform
• Characterizing the continuous gravitational-wave signal from boson clouds around Galactic isolated black holes
• All-sky search for gravitational wave emission from scalar boson clouds around spinning black holes in LIGO O3 data
• Narrowband searches for continuous and long-duration transient gravitational waves from known pulsars in the LIGO-Virgo third observing run
• All-sky Search for Continuous Gravitational Waves from Isolated Neutron Stars in the Early O3 LIGO Data
• Search methods for continuous gravitational-wave signals from unknown sources in the advanced-detector era
• Status and perspectives of Continuous Gravitational Wave searches

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• The Science of the Einstein Telescope
• Searches for continuous gravitational waves from neutron stars: A twenty-year retrospective
• Enabling multi-messenger astronomy with continuous gravitational waves: early warning and sky localization of binary neutron stars in Einstein Telescope
• Search for continuous gravitational wave signals from luminous dark photon superradiance clouds with LVK O3 observations