# Implications of a density dependent IMF for the statistics of progenitors of gravitational wave sources

## TL;DR

This paper investigates how a density-dependent initial mass function (IMF) affects the predicted formation rates of gravitational wave progenitors in stellar clusters, with implications for understanding black hole populations and cosmic ionization.

## Contribution

It introduces the consideration of a density-dependent IMF in simulations, challenging the standard Salpeter slope assumption at high stellar densities.

## Key findings

- A flatter high-mass IMF increases the predicted GW progenitor formation rates.
- Density dependence of the IMF influences the mass distribution of compact object mergers.
- Results affect interpretations of the black hole mass gap and cosmic ionization history.

## Abstract

Observations of mergers of multi-compact object systems offer insights to the formation processes of massive stars in globular clusters. Simulations of stellar clusters, may be used to understand and interpret observations. Simulations generally adopt an Initial Mass Function (IMF) with a Salpeter slope at the high mass end, for the initial distribution of stellar masses. However, observations of the nearest high mass star forming regions point to the IMF at the high mass end being flatter than Salpeter, in regions where the stellar densities are high. We explore the impact of this on the formation rate of potential GW sources, estimated from standard considerations. Globular clusters being significant contributors to the ionization history of the universe, the results have implications for the same. It impacts our ability to explore the putative mass gap, between the upper limit for neutron star masses and the lower limit for black hole masses, also.