The core-cusp problem in cold dark matter halos and supernova feedback: Effects of Mass Loss

TL;DR

This study uses N-body simulations to examine how gas removal from galaxy centers affects dark matter halo density profiles, finding that stellar feedback-driven mass loss alone cannot flatten the central cusp.

Contribution

It demonstrates that the timescale of gas ejection influences halo profiles but does not produce the observed core flattening, challenging previous assumptions about stellar feedback effects.

Findings

Short-term mass loss results in flatter density profiles.

The central cusp persists despite mass loss in simulations.

Slow mass loss restores universal CDM halo profiles.

Abstract

The core-cusp problem remains as one of the unsolved discrepancies between observations and theories predicted by the standard paradigm of cold dark matter (CDM) cosmology. To solve this problem, we perform N-body simulations to study the nonlinear response of CDM halos to the variance of the gravitational potential induced by gas removal from galaxy centers. In this study, we focus on the timescale of the gas ejection, which is strongly correlated with stellar activities, and demonstrate that it is one of the key factors in determining the dynamical response of CDM halos. The results of simulations show that the power-low index of the mass-density profile of the dark matter halo correlated with the timescale of the mass loss, and it is flatter when the mass loss occurs over a short time than when it occurs over a long time. However, it is still larger than typical observational values; in other words, the central cusp remains for any mass loss model in the simulations. Moreover, for the slow mass-loss case, the final density profile of the dark matter halo recovers the universal density profiles predicted by the CDM cosmology. Therefore, mass loss driven by stellar feedback may not be an effective mechanism to flatten the central cusp.