Limits on initial mass segregation in young clusters

TL;DR

This paper uses n-body simulations to investigate how much initial mass segregation can exist in young star clusters, challenging the idea that observed segregation is always primordial.

Contribution

It provides constraints on initial mass segregation in young clusters by analyzing simulation results, impacting star formation theories.

Findings

Primordial mass segregation is inconsistent with observations in clusters younger than a few crossing times.

Simulations show limited initial segregation can explain observed levels in young clusters.

Results challenge theories predicting widespread primordial mass segregation.

Abstract

Mass segregation is observed in many star clusters, including several that are less than a few Myr old. Timescale arguments are frequently used to argue that these clusters must be displaying primordial segregation, because they are too young to be dynamically relaxed. Looking at this argument from the other side, the youth of these clusters and the limited time available to mix spatially distinct populations of stars can provide constraints on the amount of initial segregation that is consistent with current observations. We present n-body experiments testing this idea, and discuss the implications of our results for theories of star formation. For system ages less than a few crossing times, we show that star formation scenarios predicting general primordial mass segregation are inconsistent with observed segregation levels.