Exploration about the origin of galactic and extragalactic star clusters through simulated H-R diagrams

TL;DR

This study uses simulated H-R diagrams via MCMC to investigate the origins of star clusters in our Galaxy and SMC, identifying different formation conditions based on metallicity and star formation history.

Contribution

It introduces a novel simulation approach combining MCMC with various star formation histories and luminosity functions to analyze star cluster origins.

Findings

Poor metallicity (Z=0.0004) with Gaia LF suggests globular cluster formation.

Enriched medium (Z=0.019) favors different SFH and LF combinations for cluster formation.

Different galaxy environments require distinct star formation and luminosity function models.

Abstract

The present work explores the origin of the formation of star clusters in our Galaxy and in Small Magellanic Cloud (SMC) through simulated H-R diagrams and compare those with observed star clusters. The simulation study produces synthetic H-R diagrams by Markov Chain Monte Carlo (MCMC) technique using star formation history (SFH), luminosity function (LF), abundance of heavy metal (Z) and a big library of isochrones as basic inputs and compares them with observed H-R diagrams of various star clusters. The distance based comparison between those two diagrams is carried out through two dimensional matching of points in Color-Magnitude Diagram (CMD) after optimal choice of bin size and appropriate distance function. It is found that a poor medium of heavy elements (Z = 0.0004), Gaia LF along with mixture of multiple Gaussian distributions of SFH may be the origin of formation of globular clusters (GCs). On the contrary, enriched medium (Z = 0.019) is favoured with Gaia LF along with double power law (i.e. unimodal) SFH. For SMC clusters, the choice of exponential LF and exponential SFH is a proper combination for poor medium whereas Gaia LF with Beta type SFH is preferred in an enriched medium for the formation of star clusters.