Cosmological Impacts of Black Hole Mergers: No Relief in Sight for the Hubble Tension

Abstract

The values of the Hubble constant inferred from local measurements and the cosmic microwave background (CMB) exhibit an approximately 5 sigma tension. Some have suggested this tension is alleviated if matter is converted to dark radiation via dark matter decay. As it is not clear that dark matter decays, we instead examine the effects of converting matter to gravitational radiation via black hole mergers. We consider mergers of supermassive black holes (SMBHs), mergers of stellar-mass black holes, and the formation of SMBHs from mergers of smaller black holes. We find that these processes cannot alleviate the tension, as an unrealistically large merger rate, or an overproduction of SMBHs is required. We also consider whether one can use the Integrated Sachs-Wolfe effect to constrain mechanisms that form SMBHs from mergers of smaller black holes. We find that this is also too small to be viable.

Updated after acceptance to Physical Review D

References in corpus (11)

• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• Dark matter and the early Universe: a review
• Baryon acoustic oscillations from the complete SDSS-III Ly$\alpha$-quasar cross-correlation function at $z=2.4$
• Late universe decaying dark matter can relieve the H_0 tension
• Remnant mass, spin, and recoil from spin aligned black-hole binaries
• Massive black hole binary systems and the NANOGrav 12.5 year results
• Cosmological constraints on late-universe decaying dark matter as a solution to the $H_0$ tension
• The Cosmic Microwave Background: The history of its experimental investigation and its significance for cosmology
• Supermassive Black Hole Merger Rates: Uncertainties from Halo Merger Theory
• Mergers of primordial black holes in extreme clusters and the $H_0$ tension
• Cosmological constraints on the radiation released during structure formation