The impact of cored density profiles on the observable quantities of dwarf spheroidal galaxies

TL;DR

This study uses modified chemo-dynamical simulations to assess how self-interacting dark matter affects observable properties of dwarf galaxies, finding that core formation does not significantly alter observable quantities.

Contribution

It introduces a modified chemo-dynamical code to simulate SIDM effects on dwarf galaxies and demonstrates the observational indiscernibility of dark matter cores in quenched galaxies.

Findings

Large dark matter cores do not significantly change observable properties.

Observable quantities are dominated by stochastic stellar buildup.

Inferred density profiles from line-of-sight velocities may be unreliable.

Abstract

We modify the chemo-dynamical code GEAR to simulate the impact of self-interacting dark matter on the observable quantities of 19 low mass dwarf galaxies with a variety star forming properties. We employ a relatively high, velocity independent cross-section of $\sigma/m = 10$cm$^2$/g and extract, in addition to integrated quantities, the total mass density profile, the luminosity profile, the line-of-sight velocities, the chemical abundance and the star formation history. We find that despite the creation of large cores at the centre of the dark matter haloes, the impact of SIDM on the observable quantities of quenched galaxies is indiscernible, dominated mostly by the stochastic build up of the stellar matter. As such we conclude that it is impossible to make global statements on the density profile of dwarf galaxies from single or small samples. Although based mostly on quenched galaxies, this finding supports other recent work putting into question the reliability of inferred cored density profiles that are derived from observed line-of-sight velocities.