Star cluster "infant mortality" in the Small Magellanic Cloud (Redivivus)

TL;DR

This study analyzes star cluster survival in the Small Magellanic Cloud, finding that infant mortality is significantly lower than previously thought, with at most 30% disruption in early ages, challenging earlier high-mortality claims.

Contribution

It provides a homogeneous, self-consistent analysis of cluster age and mass distributions, offering new evidence against high infant mortality rates in the SMC.

Findings

Maximum 30% infant mortality between 3-160 Myr

Ruled out 90% cluster mortality per decade up to 1 Gyr at >6 sigma

Supports low early disruption rates in SMC clusters

Abstract

The early evolution of star clusters in the Small Magellanic Cloud (SMC) has been the subject of significant recent controversy, particularly regarding the importance and length of the earliest, largely mass-independent disruption phase (referred to as "infant mortality"). Here, we take a fresh approach to the problem, using an independent, homogeneous data set of UBVR imaging observations, from which we obtain the SMC's cluster age and mass distributions in a self-consistent manner. We conclude that the (optically selected) SMC star cluster population has undergone at most ~30 per cent (1 sigma) infant mortality between the age range from about (3-10) Myr, to that of approximately (40-160) Myr. We rule out a 90 per cent cluster mortality rate per decade of age (for the full age range up to 10^9 yr) at a > 6 sigma level. We independently affirm this scenario based on the age distribution of the SMC cluster sample.