Searching for double-peak and doubly-broken gravitational-wave spectra from Advanced LIGO-Virgo's first three observing runs 后印本

摘要: The current LIGO-Virgo observing run has been pushing the sensitivity limit to touch the stochastic gravitational-wave backgrounds (SGWBs). However, no significant detection has been reported to date for any single dominated source of SGWBs with a single broken-power-law (BPL) spectrum. Nevertheless, it could equally well escape from existing Bayesian searches from, for example, two comparable dominated sources with two separate BPL spectra (double-peak case) or a single source with a doubly-BPL (DBPL) spectrum (doubly-broken case). In this paper, we put constraints on these two cases from Advanced LIGO-Virgo's first three observing runs. We found strong negative evidence for the double-peak case and hence place 95\% confidence-level (CL) upper limits $\Omega_\mathrm{BPL,1}<2.5\times10^{-7}$ and $\Omega_\mathrm{BPL,2}<9.4\times10^{-8}$ on the two BPL spectra amplitudes with respect to the unresolved compact-binary-coalescence (CBC) amplitude $\Omega_\mathrm{CBC}<5.6\times10^{-9}$. We further found weak negative evidence for the doubly-broken case and hence place 95\% CL upper limit $\Omega_\mathrm{DBPL}<1.7\times10^{-7}$ on the overall amplitude of the DBPL spectrum with respect to $\Omega_\mathrm{CBC}<6.0\times10^{-9}$. The implications of cosmological first-order phase transitions are also discussed.