Binary black holes population and cosmology in new lights: Signature of PISN mass and formation channel in GWTC-3
Résumé
The mass, spin, and merger rate distribution of the binary black holes (BBHs) across cosmic redshifts provide a unique way to shed light on their formation channel. Along with the redshift dependence of the BBH merger rate, the mass distribution of BBHs can also exhibit redshift dependence due to different formation channels and due to its dependence on the metallicity of the parent stars. In this work, we explore the redshift dependence of the BBH mass distribution jointly with the merger rate evolution from the third gravitational wave (GW) catalog GWTC-3 of the LIGO-Virgo-KAGRA collaboration. This analysis sheds light on multiple new aspects of the BBH formation channel and mass distribution. We obtain interesting constraints on the minimum delay time between the formation of stars and mergers of BBHs $t^{\rm min}_d = 1.95^{+0.97}_{-0.93}$ Gyrs, along with a hint towards a steeper power-law form of the delay time distribution ($(t_d)^{d}$) with an index $d < -1.55$ at 68$\%$ C.L. The mass distribution of the BBHs agrees with a power-law form with a Gaussian peak at $\mu_g=40.26^{+1.04}_{-2.32} $$\rm M_\odot$ which agrees with the theoretical prediction of the lower edge of the PISN mass scale and differs from the previous analysis. This analysis sheds light on the lower edge of the PISN mass scale of black holes and provides hints toward the formation channel of the BBH systems that are different from the usual fiducial scenario with a power-law index $d=-1$. Our results are consistent with the scenarios of varying (or fixed) Hubble constant and also for events with lower matched filtering network signal to noise ratio.
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