利用激光干涉引力波观测台（LIGO）-室女座（Virgo）O2数据搜寻低质量比双星系统中的亚太阳质量原初黑洞及其对原初黑洞暗物质占比的启示

本文利用LIGO-Virgo第二次观测运行（O2）的数据，搜寻了包含亚太阳质量黑洞的双黑洞并合事件。研究在未发现确切探测结果的前提下，推导了原初黑洞并合率的上限，并探讨了其对早期宇宙热史及暗物质占比的意义。

arXiv:2105.11449v2 Announce Type: replace Abstract: We perform a search for binary black hole mergers with one sub-solar mass (SSM) black hole and a primary component above $\sim 2 M_\odot$ in data from the second observing run (O2) of the LIGO-Virgo detectors. Our analysis extends the parameter space explored by previous LIGO-Virgo Collaboration searches for binaries containing SSM components into a region of parameter space motivated by broad mass distributions of primordial black holes (PBHs) exhibiting a peak around $[2-3] M^{}_\odot$, which can arise from the reduction of the equation of state during the QCD phase transition in the early Universe. Four candidate events are found passing a signal-to-noise ratio (SNR) threshold of 8 and a false alarm rate (FAR) threshold of 2 per year, although none are statistically significant enough to constitute a confident detection. Assuming a null result for the search, we derive PBH model-independent 90\% confidence upper limits on the PBH merger rates by estimating the sensitive volume-time of the search using simulated gravitational-wave signal injections. We interpret these observational limits using a representative broad PBH mass function bearing imprints of the thermal history of the early Universe and considering both early and late PBH binary formation channels.