# Populations of stellar mass Black holes from binary systems

## TL;DR

This paper models black hole populations from binary systems in galaxies, predicting their characteristics and abundance, and providing data for future observational studies and surveys.

## Contribution

It introduces a realistic evolutionary model for black hole populations from binaries, including effects of initial parameters and metallicity, and offers a publicly available database.

## Key findings

- Black hole populations are dominated by single black holes from binary disruptions.
- Approximately 26 microlensing events per year are expected due to black holes in the Galactic Bulge.
- The population characteristics are significantly influenced by initial parameters and metallicity.

## Abstract

In large and complicated stellar systems like galaxies it is difficult to predict the number and characteristics of a black hole population. Such populations may be modelled as an aggregation of homogeneous (i.e. having uniform star formation history and the same initial chemical composition) stellar populations. Using realistic evolutionary models we predict the abundances and properties of black holes formed from binaries in these environments. We show that the black hole population will be dominated by single black holes originating from binary disruptions and stellar mergers. Furthermore, we discuss how black hole populations are influenced by such factors as initial parameters, metallicity, initial mass function, and natal kick models. As an example application of our results, we estimate that about 26 microlensing events to happen every year in the direction of the Galactic Bulge due to black holes in a survey like OGLE-IV. Our results may be used to perform in-depth studies related to realistic black hole populations, e.g. observational predictions for space survey missions like Gaia, or Einstein Probe. We prepared a publicly available database with the raw data from our simulations to be used for more in-depth studies.