Speaker
Description
As the number of gravitational wave detections of binary black hole (BBH) mergers grows, so do the challenges in reconciling theoretical models with observations. Currently, state-of-the-art binary population synthesis codes tend to overpredict the BBH merger rate density compared to the value inferred from LIGO-Virgo_KAGRA observations. A key factor shaping BBH merger rates is the metal-dependent star formation rate (SFR), as metallicity plays a crucial role in the evolution of massive stars. In this talk, I will address the question: can uncertainties in the metal-dependent SFR explain the tension between models and observations?
Remarkably, my results show that a better modelling of the cosmic SFR leads to an increase in the BBH merger rates. I will show that the source of the discrepancy likely does not lie in the treatment of the metal-dependent SFR but rather stems from stellar evolution models and/or BBH formation channels. I will discuss the astrophysical implications of these results as well as potential solutions to resolve the tension.