The Impact of metallicity evolution of the universe on the maximum mass of LIGO binary black holes

TL;DR

This paper examines how the evolution of metallicity in the universe affects the maximum mass of black holes observed by LIGO, showing that assumptions about metallicity history significantly influence mass bounds.

Contribution

It introduces models linking metallicity evolution to black hole mass limits and quantifies how different evolution scenarios impact these bounds based on LIGO data.

Findings

Rapid metallicity evolution constrains maximum black hole mass to about 44 solar masses.

Modest metallicity evolution allows for a higher maximum mass around 52 solar masses.

The inferred black hole mass limit strongly depends on the assumed metallicity evolution model.

Abstract

We can be biased against observing massive black holes to merge in the local universe as the bounds on the maximum black hole mass ($M_{BH}^{\rm max}$) depends on the assumptions regarding the metallicity evolution of the star forming gas across the cosmic time. We investigate the bounds on the metallicity evolution, mass distribution and delay times of the binary black hole sources based on the ten observed events by LIGO. We parametrize $M_{BH}^{\rm max}$ to be a function of metallicity which itself is modeled to evolve with redshift in either a modest or rapid fashion. Rapid metallicity evolution models predict a stringent bound of $M_{BH}^{\rm max}=44^{+9}_{-5}M_{\odot}$, while the bound on $M_{BH}^{\rm max}$ in the models with modest metallicity evolution is $M_{BH}^{\rm max}=52^{+16}_{-9} M_{\odot}$. Therefore, inferring $M_{BH}^{\rm max}$ from GW data depends on the assumed metal enrichment history of the universe that is not severely constrained at the moment.