Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results

TL;DR

BPASS v2.1 offers advanced binary stellar evolution models that effectively match observed stellar populations and galaxy properties across different redshifts, enhancing understanding of stellar and galactic evolution.

Contribution

This paper introduces BPASS v2.1, a new version of binary stellar models incorporating binary interactions, and demonstrates its ability to reproduce diverse observational data.

Findings

Successfully reproduces colours and properties of resolved stellar populations.

Accurately models supernova progenitors and their observed characteristics.

Provides a consistent explanation for galaxy properties across redshifts.

Abstract

The Binary Population and Spectral Synthesis (BPASS) suite of binary stellar evolution models and synthetic stellar populations provides a framework for the physically motivated analysis of both the integrated light from distant stellar populations and the detailed properties of those nearby. We present a new version 2.1 data release of these models, detailing the methodology by which BPASS incorporates binary mass transfer and its effect on stellar evolution pathways, as well as the construction of simple stellar populations. We demonstrate key tests of the latest BPASS model suite demonstrating its ability to reproduce the colours and derived properties of resolved stellar populations, including well- constrained eclipsing binaries. We consider observational constraints on the ratio of massive star types and the distribution of stellar remnant masses. We describe the identification of supernova progenitors in our models, and demonstrate a good agreement to the properties of observed progenitors. We also test our models against photometric and spectroscopic observations of unresolved stellar populations, both in the local and distant Universe, finding that binary models provide a self-consistent explanation for observed galaxy properties across a broad redshift range. Finally, we carefully describe the limitations of our models, and areas where we expect to see significant improvement in future versions.