Repeated gravitational wave bursts from cosmic strings

Author(s)

Auclair, Pierre, Steer, Danièle A., Vachaspati, Tanmay

Abstract

A characteristic observational signature of cosmic strings are short duration gravitational wave (GW) bursts. These have been searched for by the LIGO-Virgo-KAGRA (LVK) Collaboration and will be searched for with LISA. We point out that these burst signals are repeated, since cosmic string loops evolve quasiperiodically in time, and will always appear from essentially the same position in the sky. We estimate the number of GW repeaters for LVK and LISA and show that the string tension that can be probed scales as detector sensitivity to the sixth power, which raises hope for detection in future GW detectors. The observation of repeated GW bursts from the same cosmic string loop helps distinguish between the GW waveform parameters and the sky localization.

Figures

Caption

Number of repeaters per logarithmic bin of the period, $T=\ell/2$, as seen by different GW detectors for $G\mu=10^{-10}$. The solid line shows \cref{eq:rate-nogain}, ignoring repetitions. The dashed line shows \cref{eq:rate-gain}, namely including the sensitivity gain due to repetition. If not all repeaters are observed, one would expect a rate somewhere in the shaded regions. (Assuming $T_O = 4$ years for each detector.)

Caption

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Caption

: : Modulation of the SNR in the reference frame of LISA for a repeating burst of amplitude $A = 10^{-21}$ in the equatorial plane (red) and at colatitude $\pi / 4$ (orange) and with same longitude. Left panel: antenna pattern of LISA in its own reference frame using Time Delay Interferometry (TDI) and generation 1.5 variables~ \cite{Tinto:2020fcc,Auclair:2023brk}. Right panel: evolution of the SNR over the course of one year.