Indirect dark matter signatures in the cosmic dark ages. I. Generalizing the bound on s-wave dark matter annihilation from Planck results

By T. Slatyer. 2015

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Recent measurements of the cosmic microwave background (CMB) anisotropies by Planck provide a sensitive probe of dark matter annihilation during the cosmic dark ages, and specifically constrain the annihilation parameter $f_\mathrm{eff} \langle \sigma v \rangle/m_\chi$. Using new results (Paper II) for the ionization produced by particles injected at arbitrary energies, we calculate and provide $f_\mathrm{eff}$ values for photons and $e^+e^-$ pairs injected at keV-TeV energies; the $f_\mathrm{eff}$ value for any dark matter model can be obtained straightforwardly by weighting these results by the spectrum of annihilation products. This result allows the sensitive and robust constraints on dark matter annihilation presented by the Planck Collaboration to be applied to arbitrary dark matter models with $s$-wave annihilation. We demonstrate the validity of this approach using principal component analysis. As an example, we integrate over the spectrum of annihilation products for a range of Standard Model final states to determine the CMB bounds on these models as a function of dark matter mass, and demonstrate that the new limits generically exclude models proposed to explain the observed high-energy rise in the cosmic ray positron fraction. We make our results publicly available at this http URL

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7ca0e1d0aa09160326ae9c849f846f3baf5cd7ca

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Citations in the corpus

Dark matter models and direct detection (2019, background): “where f (z) is typically an O(1) number characterizing the efficiency of energy deposition at redshift z [83, 84].”
Cosmological constraints on exotic injection of electromagnetic energy (2016, background): “[19, 24] give the transfer functions per channel for a given ionisation history (Recfast-like, without reionization).”
Neutrino decoupling beyond the Standard Model: CMB constraints on the Dark Matter mass with a fast and precise Neff evaluation (2018, background): “m3=s regardless of the behaviour at low velocities [45,62,63]. This makes our bounds particularly relevant for p-wave annihilating relics to electrons since CMB observations are not sensitive to them [2,64]. This will be for instance the case of a Majorana dark matter particle annihilating to electr”
Characterization of subhalo structural properties and implications for dark matter annihilation signals (2016, background): “…microwave background anisotropy (for recent analyses, see, e.g., Lopez-Honorez et al. (2013); Diamanti et al. (2014); Madhavacheril et al. (2014); Ade et al. (2015); Slatyer (2016); Kawasaki et al. (2015)). and definitive substructure boost model, some important issues still remain for future work.”