Speaker
Description
This study presents the modeling of the gravitational wave (GW) bias parameter by bridging a connection between simulated GW sources and galaxies in low redshift galaxy surveys 2MPZ, WISC and SDSS DR7. We study this connection by creating a mock host catalog for GW events, populating galaxy surveys with binary black holes (BBHs) for different scenarios of the GW host-galaxy probability as a function of the galaxy stellar mass, SFR and metallicity. For 2MPZ, WISC galaxy surveys with stellar mass information, we consider a phenomenological broken power law model for the host-galaxy probability function, with a potential turnover where the star formation efficiency begins to drop. We vary the parameters of the GW host-galaxy probability function and find that generically the GW bias increases as the turnover point (MK) increases. The change in the GW bias parameter shows a maximum change of about 30% for different scenarios explored in this work in comparison to the galaxy bias. For the SDSS DR7 survey with stellar mass, SFR and metallicity information, we use a joint host-galaxy probability function defined over stellar mass, star formation rate (SFR), and metallicity. Each of these probability components is modeled as a broken power law with turnover points, motivated by the astrophysical processes. We find that the GW bias increases with stellar mass, reflecting the correlation between stellar and halo mass. Conversely, the GW bias decreases with increasing SFR, and shows no significant dependence on host galaxy metallicity or the masses of the black holes in the binary. These results suggest that the spatial clustering of GW sources is primarily shaped by the stellar mass and SFR of their host galaxies. Future measurements of the GW bias can help constrain the parameter of the host-galaxy probability functions and thus offer insights into the underlying astrophysical processes.