The dynamical state of the Globular Cluster M10 (NGC 6254)

TL;DR

This study investigates the radial variation of the stellar mass function in globular cluster M10 using HST data, comparing observations with simulations to explore the presence of an intermediate-mass black hole or primordial binaries affecting cluster dynamics.

Contribution

The paper combines deep HST observations with N-body simulations to analyze mass segregation and assess the potential presence of an IMBH or primordial binaries in M10.

Findings

Mass segregation profile suggests energy sources like an IMBH or binaries are quenching segregation.

Observational data cannot definitively confirm the presence of an IMBH due to uncertainties.

Both an IMBH and a binary fraction of about 5% can explain the observed profiles.

Abstract

Studying the radial variation of the stellar mass function in globular clusters (GCs) has proved a valuable tool to explore the collisional dynamics leading to mass segregation and core collapse. In order to study the radial dependence of the luminosity and mass function of M 10, we used ACS/HST deep high resolution archival images, reaching out to approximately the cluster's half-mass radius (rhm), combined with deep WFPC2 images that extend our radial coverage to more than 2 rhm. From our photometry, we derived a radial mass segregation profile and a global mass function that we compared with those of simulated clusters containing different energy sources (namely hard binaries and/or an IMBH) able to halt core collapse and to quench mass segregation. A set of direct N-body simulations of GCs, with and without an IMBH of mass 1% of the total cluster mass, comprising different initial mass functions (IMFs) and primordial binary fractions, was used to predict the observed mass segregation profile and mass function. The mass segregation profile of M 10 is not compatible with cluster models without either an IMBH or primordial binaries, as a source of energy appears to be moderately quenching mass segregation in the cluster. Unfortunately, the present observational uncertainty on the binary fraction in M10 does not allow us to confirm the presence of an IMBH in the cluster, since an IMBH, a dynamically non-negligible binary fraction (~ 5%), or both can equally well explain the radial dependence of the cluster mass function.