HEP Colloquia 2024

by Ulyana Dupletsa (GSSI)

Tuesday 23 Apr 2024, 14:30 → 16:00 Europe/Rome

Sala Consiliare (Department of Physics)

ET forecasts on cosmological growth of BH masses

Gravitational-wave astronomy has been a leading field in probing the Universe since the discovery of gravitational waves (GWs). We employ GW signals to investigate an innovative hypothesis: the potential impact of the Universe's expansion on black hole mass, positing that black hole masses may inherently increase due to cosmological expansion. This hypothesis is based on the assumption that black holes are not singular objects.

We want to determine whether we will be able to assess if black holes are singular or not, by estimating the uncertainty with which the two scenarios can be distinguished. To this scope, we will use a mock set of GW signals from binary black hole (BBH) populations, as predicted to be detected with the Einstein Telescope (ET). Next-generation GW detectors, in fact, are expected to observe up to 10⁵ BBHs per year giving us large statistics. Our analysis involves two primary steps. Firstly, we will use an approximate parameter estimation method implemented in the GWFish software based on Fisher matrix to estimate the mass and redshift of the BBH populations, as full GW parameter analysis relies on Markov Chain Monte Carlo or nested sampling methods, which require a prohibitive amount of computational time given the large amount of events. Secondly, we will conduct a Bayesian analysis to estimate the value of the coupling constant and its error using the Fisher results from two different population samples, one simulated with cosmological coupling, and the other without cosmological coupling.