Future global 21-cm observations could beat CMB limits on TeV-scale decaying dark matter for lifetimes ≳10^15 s, especially for decays into neutrinos.
21cm Limits on Decaying Dark Matter and Primordial Black Holes
5 Pith papers cite this work. Polarity classification is still indexing.
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abstract
Recently the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) reported the detection of a 21cm absorption signal stronger than astrophysical expectations. In this paper we study the impact of radiation from dark matter (DM) decay and primordial black holes (PBH) on the 21cm radiation temperature in the reionization epoch, and impose a constraint on the decaying dark matter and PBH energy injection in the intergalactic medium, which can heat up neutral hydrogen gas and weaken the 21cm absorption signal. We consider decay channels DM$\rightarrow e^+e^-, \gamma\gamma$, $\mu^+\mu^-$, $b\bar{b}$ and the $10^{15-17}$g mass range for primordial black holes, and require the heating of the neutral hydrogen does not negate the 21cm absorption signal. For $e^+e^-$, $\gamma\gamma$ final states and PBH cases we find strong 21cm bounds that can be more stringent than the current extragalactic diffuse photon bounds. For the DM$\rightarrow e^+e^-$ channel, the lifetime bound is $\tau_{\rm DM}> 10^{27}$s for sub-GeV dark matter. The bound is $\tau_{\rm DM}\ge 10^{26}$s for sub-GeV DM$\rightarrow \gamma\gamma$ channel and reaches $10^{27}$s at MeV DM mass. For $b\bar{b}$ and $\mu^+\mu^-$ cases, the 21 cm constraint is better than all the existing constraints for $m_{\rm DM}<20$ GeV where the bound on $\tau_{\rm DM}\ge10^{26}$s. For both DM decay and primordial black hole cases, the 21cm bounds significantly improve over the CMB damping limits from Planck data.
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representative citing papers
A model in which inflaton energy goes exclusively to a dark sector, delaying SM thermalization until a false-vacuum decay produces a GW background with present-day Omega_GW up to 3e-8.
Compact dark stars from asymmetric dark matter may inject energy that significantly deviates the 21-cm brightness temperature evolution from standard cosmology, offering a new probe for particle dark matter.
Bulk viscosity raises the critical collapse threshold for primordial black holes by an amount comparable to the viscosity strength and increases the resulting black hole masses.
Updated compilation shows PBHs are tightly constrained across 55 orders of magnitude in mass, ruling out dominant dark matter contributions except in narrow windows, with many limits carrying observational uncertainties.
citing papers explorer
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Cosmological constraints on TeV-scale dark matter subcomponents decaying between recombination and reionisation
Future global 21-cm observations could beat CMB limits on TeV-scale decaying dark matter for lifetimes ≳10^15 s, especially for decays into neutrinos.
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A New Origin of the Big Bang from Dark-Sector-Induced Vacuum Decay and Its Gravitational-Wave Signal
A model in which inflaton energy goes exclusively to a dark sector, delaying SM thermalization until a false-vacuum decay produces a GW background with present-day Omega_GW up to 3e-8.
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Imprints of energy injection by compact dark stars in the 21-cm signal
Compact dark stars from asymmetric dark matter may inject energy that significantly deviates the 21-cm brightness temperature evolution from standard cosmology, offering a new probe for particle dark matter.
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Primordial black hole formation in bulk-viscous cosmology
Bulk viscosity raises the critical collapse threshold for primordial black holes by an amount comparable to the viscosity strength and increases the resulting black hole masses.
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Constraints on Primordial Black Holes
Updated compilation shows PBHs are tightly constrained across 55 orders of magnitude in mass, ruling out dominant dark matter contributions except in narrow windows, with many limits carrying observational uncertainties.