The effects of asymmetric dark matter on stellar evolution – I. Spin-dependent scattering

Abstract

Most of the dark matter (DM) search over the last few decades has focused on WIMPs, but the viable parameter space is quickly shrinking. Asymmetric Dark Matter (ADM) is a WIMP-like DM candidate with slightly smaller masses and no present day annihilation, meaning that stars can capture and build up large quantities. The captured ADM can transport energy through a significant volume of the star. We investigate the effects of spin-dependent ADM energy transport on stellar structure and evolution in stars with 0.9 ≤ M⋆/M⊙ ≤ 5.0 in varying DM environments. We wrote a MESA module* that calculates the capture of DM and the subsequent energy transport within the star. We fix the DM mass to 5 GeV and the cross-section to 10−37 cm2, and study varying environments by scaling the DM capture rate. For stars with radiative cores (0.9 ≤ M⋆/M⊙ ≲ 1.3 ), the presence of ADM flattens the temperature and burning profiles in the core and increases MS (Xc > 10−3) lifetimes by up to $\sim 20{{\ \rm per\ cent}}$. We find that strict requirements on energy conservation are crucial to the simulation of ADM’s effects on these stars. In higher-mass stars, ADM energy transport shuts off core convection, limiting available fuel and shortening MS lifetimes by up to $\sim 40{{\ \rm per\ cent}}$. This may translate to changes in the luminosity and effective temperature of the MS turnoff in population isochrones. The tip of the red giant branch may occur at lower luminosities. The effects are largest in DM environments with high densities and/or low velocity dispersions, making dwarf and early forming galaxies most likely to display the effects.

On asymmetric dark matter constraints from the asteroseismology of a subgiant star

“…One other effect that is found in this model is the extension of the MS lifetime Raen et al 2021). While the star with DM has a radiative core during the largest part of its MS lifetime, and thus nuclear burning is limited to the local hydrogen supply, the decrease in central temperature slows down the hydrogen burning rate thus extending the MS lifetime.…”

“…Taoso et al 2010;Iocco et al 2012;Casanellas & Lopes 2013;Casanellas et al 2015;Lopes & Silk 2002). More recently, Raen et al (2021) studied the effects of ADM on the stellar evolution of 0.9 -5 M stars for 𝜎 SD = 10 −37 cm 2 and higher DM densities (𝜌 DM ∼ 10 2 − 10 5 GeV/cm 3 ). Their findings align with the results of this work, having reported a generalised suppression of convection in the cores of stars with masses 𝑀 1.3 𝑀 added to a flattening of the temperature profile in the core and an increase in MS lifetimes by up to 20% for stars with 0.9 𝑀/𝑀 1.3.…”

Influence of dark matter on gravitational stability of isothermal gas clouds

“…However, the DM presence must have a significant influence on the entire evolution of stars, from the protostellar clouds to the compact objects formation. Several recent works (Raen et al (2021); Ellis (2021); Sagun et al (2021),Lopes, José & Lopes, Ilídio (2021) have focused on the effects of DM particle captured by stars and theirs possible observational manifestations. In addition, it would be useful to consider the gravitational stability of stars in the approach presented in this paper to find out the influence of DM on their fates.…”

Dark Matter-admixed Rotating White Dwarfs as Peculiar Compact Objects

“…It is possible that stars contain a DM component. The effect of DM on stellar evolution could be significant depending on the stellar evolution models [4,[6][7][8][9][10][11]. Therefore, anomalous stars could be used as probes for astrophysical DM.…”