Constraining axion and compact dark matter with interstellar medium heating

TL;DR

This paper uses interstellar medium heating rates in dwarf galaxy Leo T and Milky Way clouds to set new constraints on various dark matter models, including axions and compact objects, complementing direct detection efforts.

Contribution

It introduces a novel astrophysical method to constrain dark matter interactions using interstellar gas heating in specific gas-rich environments.

Findings

Constraints on axion-hydrogen and axion-electron interactions.

Limits on relic magnetically charged dark matter deceleration.

Bounds on dynamical friction from compact dark matter.

Abstract

Cold interstellar gas systems have been used to constrain dark matter (DM) models by the condition that the heating rate from DM must be lower than the astrophysical cooling rate of the gas. Following the methodology of Wadekar and Farrar (2021), we use the interstellar medium of a gas-rich dwarf galaxy, Leo T, and a Milky Way-environment gas cloud, G33.4-8.0 to constrain DM. Leo T is a particularly strong system as its gas can have the lowest cooling rate among all the objects in the late Universe (owing to the low volume density and metallicity of the gas). Milky Way clouds, in some cases, provide complementary limits as the DM-gas relative velocity in them is much larger than that in Leo T. We derive constraints on the following scenarios in which DM can heat the gas: $(i)$ interaction of axions with hydrogen atoms or free electrons in the gas, $(ii)$ deceleration of relic magnetically charged DM in gas plasma, $(iii)$ dynamical friction from compact DM, $(iv)$ hard sphere scattering of composite DM with gas. Our limits are complementary to DM direct detection searches. Detection of more gas-rich low-mass dwarfs like Leo T from upcoming 21cm and optical surveys can improve our bounds.