Reconstructing the Arches I: Constraining the Initial Conditions

TL;DR

This study uses N-body simulations to model the Arches cluster, aiming to match observational data and constrain its initial conditions, including mass, size, and initial mass function, by simplifying certain physical effects.

Contribution

It introduces a method to efficiently explore initial cluster parameters by neglecting Galactic potential and stellar evolution, providing new constraints on the cluster's initial mass and structure.

Findings

Initial Salpeter IMF explains the present-day mass function.

Estimated initial total mass of the cluster is approximately 5.1 x 10^4 solar masses.

Initial virial radius is about 0.76 parsecs.

Abstract

We have performed a series of N-body simulations to model the Arches cluster. Our aim is to find the best fitting model for the Arches cluster by comparing our simulations with observational data and to constrain the parameters for the initial conditions of the cluster. By neglecting the Galactic potential and stellar evolution, we are able to efficiently search through a large parameter space to determine e.g. the IMF, size, and mass of the cluster. We find, that the cluster's observed present-day mass function can be well explained with an initial Salpeter IMF. The lower mass-limit of the IMF cannot be well constrained from our models. In our best models, the total mass and the virial radius of the cluster are initially (5.1 +/- 0.8) 10^4 Msun and 0.76 +/- 0.12 pc, respectively. The concentration parameter of the initial King model is w0 = 3-5.