The degeneracy between star-formation parameters in dwarf galaxy simulations and the Mstar-Mhalo relation

TL;DR

This study uses N-Body/SPH simulations to explore how star formation and feedback parameters influence dwarf galaxy properties, revealing a degeneracy and matching some observed scaling relations but not the Mstar-Mhalo relation.

Contribution

It identifies a degeneracy between star formation threshold and feedback efficiency, and assesses their effects on dwarf galaxy simulations against observational data.

Findings

A natural core formation occurs due to feedback.

A degeneracy exists between feedback efficiency and star formation threshold.

Simulations reproduce the slope but not the normalization of the Mstar-Mhalo relation.

Abstract

We present results based on a set of N-Body/SPH simulations of isolated dwarf galaxies. The simulations take into account star formation, stellar feedback, radiative cooling and metal enrichment. The dark matter halo initially has a cusped profile, but, at least in these simulations, starting from idealised, spherically symmetric initial conditions, a natural conversion to a core is observed due to gas dynamics and stellar feedback. A degeneracy between the efficiency with which the interstellar medium absorbs energy feedback from supernovae and stellar winds on the one hand, and the density threshold for star formation on the other, is found. We performed a parameter survey to determine, with the aid of the observed kinematic and photometric scaling relations, which combinations of these two parameters produce simulated galaxies that are in agreement with the observations. With the implemented physics we are unable to reproduce the relation between the stellar mass and the halo mass as determined by Guo et al. (2010), however we do reproduce the slope of this relation.