Low-End Mass Function of the Arches Cluster

TL;DR

This study uses a novel pixel intensity histogram method to estimate the low-mass end of the Arches cluster's initial mass function, revealing it is similar to the Galactic disk IMF with a cutoff below 0.1 solar masses.

Contribution

Introduces a new photometric technique using pixel intensity histograms to analyze unresolved faint stars in the Arches cluster's IMF.

Findings

IMF cutoff mass is less than or around 0.1 Msun

IMF shape closely resembles the Kroupa IMF

Low-mass end of Arches cluster's IMF is similar to Galactic disk IMF

Abstract

The initial mass function (IMF) of the Arches cluster, which was formed a few million years ago in the harsh environment of the Galactic center (GC), has long been a target of interest to those who study the GC and the theory of star formation. The distinct star-forming conditions in the GC might have caused the cluster to have a shallower slope or an elevated lower mass cutoff in its IMF. But its mass function has been revealed only down to 1-2 Msun (the lower limit of resolved stars), and the low- end mass function of the Arches is still unknown. To estimate the unresolved part of the Arches mass function, we have devised a novel photometric method that involves the histogram of pixel intensities in the observed image, which contains information on the unresolved, faint stars. By comparing the pixel intensity histograms (PIHs) of numerous artificial images constructed from model IMFs with the observed PIH, we find that the best-fit model IMF for the Arches cluster has a cutoff mass less than or similar to 0.1 Msun and a shape very close to that of the Kroupa MF. Our findings imply that the IMF of the Arches cluster is similar to those found in the Galactic disk.