Primordial Black Hole Merger Rate in f(R) Gravity

Abstract

Primordial black holes (PBHs) are known as one of the potential candidates for dark matter. They are expected to have formed due to the direct gravitational collapse of density fluctuations in the early Universe. In this regard, examining the merger rate of PBHs within modified theories of gravity can offer a deeper insight into their abundance. In this work, we delve into the calculation of the merger rate of PBHs within the theoretical framework of f(R) gravity. Our analysis reveals an enhancement in the merger rate of PBHs compared to that obtained from general relativity. Additionally, modulating the field strength f R0 induces shifts in the PBH merger rate, presenting a potential observational signature of modified gravity. We also explore the upper bounds on the abundance of PBHs obtained from f(R) gravity models by comparing the results with gravitational-wave and observational data. The results indicate that in certain regions not excluded by benchmarking data, the parameter space for these upper bounds may be considered reliable.

Primordial Black Hole–Neutron Star Merger Rate in Modified Gravity

“…However, unlike the formation of PBH binaries, the formation of PBH-NS binaries is associated with the late-time Universe, taking place immediately after the formation of cosmological and astrophysical structures. As a result, it is anticipated that more precise models describing dark matter halos will significantly influence the density and velocity distribution of PBHs involved in these events (see, e.g., Fakhry et al 2021Fakhry et al , 2022aFakhry et al , 2022bFakhry et al , 2023bFakhry et al , 2023cFakhry 2024). Various methods have been utilized to elaborate on halo characteristics within the context of general relativity (GR; Press & Schechter 1974;Sheth & Tormen 1999;Jenkins et al 2001;Sheth et al 2001;Reed et al 2003;Warren et al 2006;Reed et al 2007;Del Popolo et al 2017;Fakhry et al 2023a).…”

On the merger rate of primordial black holes in cosmic voids

“…However, unlike the formation of PBH binaries, the formation of PBH-NS binaries is associated with the late-time Universe, taking place immediately after the formation of cosmological and astrophysical structures. As a result, it is anticipated that more precise models describing dark matter halos will significantly influence the density and velocity distribution of PBHs involved in these events (see, e.g., Fakhry et al 2021Fakhry et al , 2022aFakhry et al ,b, 2023cFakhry et al 2023b;Fakhry 2024). Various methods have been utilized to elaborate on halo characteristics within the context of GR (Press & Schechter 1974;Sheth & Tormen 1999;Sheth et al 2001;Jenkins et al 2001;Reed et al 2003;Warren et al 2006;Reed et al 2007;Del Popolo et al 2017;Fakhry et al 2023a).…”