Dark-Matter-Powered Population III Evolution: Lifetimes, Rotation, and Quasi-Homogeneity in massive Stars

TL;DR

This study investigates how dark matter annihilation influences the evolution, rotation, and chemical mixing of massive Population III stars, revealing extended lifetimes and quasi-homogeneous evolution driven by dark matter interactions.

Contribution

It introduces a detailed model of Population III star evolution incorporating WIMP capture and annihilation, showing significant effects on stellar lifetime and chemical homogeneity.

Findings

Dark matter extends stellar lifetimes from 10 million to over a billion years.

Dark matter-induced mixing leads to near solid-body rotation and homogeneous chemical profiles.

Stars exhibit distinctive chemical signatures, such as high helium and nitrogen levels, due to dark matter effects.

Abstract

Population III stars supplied the first light and metals in the Universe, setting the pace of re-ionisation and early chemical enrichment. In dense haloes their evolution can be strongly influenced by the energy released when WIMPs annihilate inside the stellar core. We follow the evolution of a \(20\,M_\odot\) Population III model with the \textsc{genec} code, adding a full treatment of spin dependent WIMP capture and annihilation. Tracks are calculated for six halo densities from \(10^{8}\) to \(3\times10^{10}\,\mathrm{GeV\,cm^{-3}}\) and three initial rotation rates between zero and \(0.4\,v/v_{\mathrm{crit}}\). As soon as the capture product reaches \(\rho_\chi\sigma_{\mathrm{SD}}\simeq2\times10^{-28}\,\mathrm{GeV\,cm^{-1}}\), the dark-matter luminosity rivals hydrogen fusion, stretching the main-sequence lifetime from about ten million years to more than a gigayear. The extra time allows meridional circulation to smooth out differential rotation; a star that begins at \(0.4\,v/v_{\mathrm{crit}}\) finishes core hydrogen burning with near solid-body rotation and a helium core almost twice as massive as in the dark-matter-free case. Because the nuclear timescale is longer, chemically homogeneous evolution now sets in at only \(0.2\,v/v_{\mathrm{crit}}\), rather than the \(\gtrsim0.5\,v/v_{\mathrm{crit}}\) required without WIMPs. For a star with \(0.4\,v/v_{\mathrm{crit}}\), the surface hydrogen fraction drops to \(X\!\sim\!0.27\), helium rises to \(Y\!\sim\!0.73\), and primary \(^{14}\mathrm N\) increases by four orders of magnitude at He exhaustion. Moderate rotation combined with plausible dark-matter densities can therefore drive primordial massive stars towards long-lived, quasi-homogeneous evolution with distinctive chemical and spectral signatures.