Dark Matter Annihilation Feedback in cosmological simulations I: Code convergence and idealised halos

TL;DR

This paper introduces a new implementation of Dark Matter Annihilation Feedback in GADGET-2, demonstrating its effects on idealised halos and initial cosmological simulations, highlighting its impact on gas evacuation and small-scale structure.

Contribution

The paper presents a novel DMAF scheme integrated into GADGET-2, with tests on idealised halos and preliminary cosmological results showing effects on baryonic matter and substructure.

Findings

DMAF can evacuate gas in low-mass, concentrated halos.

Strong DMAF effects can reduce small-scale substructure.

Potential observable impacts on dwarf galaxy baryonic content.

Abstract

We describe and test a novel Dark Matter Annihilation Feedback (DMAF) scheme that has been implemented into the well known cosmological simulation code \textsf{GADGET-2}. In the models considered here, dark matter can undergo self-annihilation/decay into radiation and baryons. These products deposit energy into the surrounding gas particles and then the dark matter/baryon fluid is self-consistently evolved under gravity and hydrodynamics. We present tests of this new feedback implementation in the case of idealised dark matter halos with gas components for a range of halo masses, concentrations and annihilation rates. For some dark matter models, DMAF's ability to evacuate gas is enhanced in lower mass, concentrated halos where the injected energy is comparable to its gravitational binding energy. Therefore, we expect the strongest signs of dark matter annihilation to imprint themselves onto the baryonic structure of concentrated dwarf galaxies through their baryonic fraction and star formation history. Finally we present preliminary results of the first self-consistent DMAF cosmological box simulations showing that the small scale substructure is washed out for large annihilation rates.