Multimessenger Constraints on Supermassive Dark Stars and Their Black Hole Remnants

TL;DR

This paper investigates how supermassive dark stars and their black hole remnants contribute to diffuse electromagnetic and neutrino backgrounds, providing new constraints on dark matter properties and early universe structure formation.

Contribution

It presents the first population-level analysis of diffuse multimessenger signals from supermassive dark stars and their black hole remnants, linking dark matter annihilation to early black hole formation.

Findings

DS-related emissions can surpass gamma-ray background for certain DM parameters.

Diffuse backgrounds can serve as probes for dark matter and early black hole formation.

Results set new constraints on dark matter properties from multimessenger observations.

Abstract

Dark matter (DM) annihilation can power the first generation of stars as long lived dark stars (DSs) that grow to supermassive scales $M_{\rm DS}\gtrsim 10^{5} M_{\odot}$ and eventually collapse into heavy black holes that could seed the supermassive black holes observed at high redshifts. We compute the diffuse electromagnetic emission from a cosmological population of such supermassive DSs and their black hole remnants, tracking the entire DS history and including thermal surface radiation, DM annihilation in adiabatically contracted halos as well as late-time emission from DM overdensity spikes around the resulting black holes. After accounting for photon attenuation, we find that DS related contributions can exceed the Fermi-LAT extragalactic $\gamma$-ray background for thermal relic annihilation cross-sections and DM masses below $\sim 1$ TeV. Our results constitute the first population integrated diffuse multimessenger constraints on supermassive DSs as progenitors of early black holes and demonstrate that diffuse photon and neutrino backgrounds offer a powerful and complementary avenue for probing the role of DM in the formation of the earliest massive structures.