Detecting dark matter annihilation with CMB polarization: Signatures and experimental prospects

By Nikhil Padmanabhan, Douglas P. Finkbeiner. 2005

275 citations recorded by the source corpus.

Dark matter (DM) annihilation during hydrogen recombination (z{approx}1000) will alter the recombination history of the Universe, and affect the observed CMB temperature and polarization fluctuations. Unlike other astrophysical probes of DM, this is free of the significant uncertainties in modelling galactic physics, and provides a method to detect and constrain the cosmological abundances of these particles. We parametrize the effect of DM annihilation as an injection of ionizing energy at a rate {epsilon}{sub DM}, and argue that this simple 'on the spot' modification is a good approximation to the complicated interaction of the annihilation products with the photon-electron plasma. Generic models of DM do not change the redshift of recombination, but change the residual ionization after recombination. This broadens the surface of last scattering, suppressing the temperature fluctuations and enhancing the polarization fluctuations. We use the temperature and polarization angular power spectra to measure these deviations from the standard recombination history, and therefore, indirectly probe DM annihilation. The modifications to the temperature power spectrum are nearly degenerate with the primordial scalar spectral index and amplitude; current CMB data are therefore unable to put any constraints on the annihilation power. This degeneracy is broken by polarization; Planck will have the sensitivitymore » to measure annihilation power {epsilon}{sub DM}(z=1000)>10{sup -15} eV/s/proton, while high sensitivity experiments (e.g. NASA's CMBpol) could improve that constraint to {epsilon}{sub DM}(z=1000)>4x10{sup -16} eV/s/proton, assuming a fractional detector sensitivity of {delta}T/T{approx}1{mu}K and a beam of 3{sup '}. These limits translate into a lower bound on the mass of the DM particle, M{sub DM}>10-100 GeV, assuming a single species with a cross section of {approx}2x10{sup -26} cm{sup 3}/s, and a fraction f{approx}0.1-1 of the rest mass energy used for ionization. The bounds for the Wilkinson microwave anisotropy probe (WMAP) 4y data are significantly lower, because of its lack of high S/N polarization measurements, but it can strongly constrain O(MeV) particles such as those proposed by Boehm et al. (2004)« less

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b4e050ea27bb0fded678ce90cf0e10b0cac7cf11

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Citations in the corpus

Dark matter models and direct detection (2019, background): “CMB photons scatter off the free electrons, leading to damping at small scales in the CMB power spectra and an increase in the power for CMB polarization (EE) at large scales [85].”
The evolution of CMB spectral distortions in the early Universe (2011, methodology): “To parametrize the rate of energy injection we use (compare Padmanabhan & Finkbeiner 2005; Chluba 2010) dE dt ∣ ∣ ∣ ∣ ∣ ann = [1 − fν] fannNH(1+ z)3, (24) where fann has dimensions eV s−1, and fν is the fraction of the total energy carried away by neutrinos.fann is related to the abundance of the…”
Towards a complete treatment of the cosmological recombination problem (2010, background): “…extensio, e.g., to account for the effect ofdark matter annihilation, energy injection by decaying particles(e.g. see Chen & Kamionkowski 2004; Padmanabhan & Finkbeiner 2005; Chluba 2010), or thevariation of fundamental constants(Kaplinghat et al. 1999; Galli et al. 2009; Scóccola et al.…”
The effects of QCD equation of state on the relic density of WIMP dark matter (2015, background): “The strongest limits on 〈σv〉 originate from the fact that WIMP annihilation heats up the plasma in the “recombination” epoch when neutral atoms first formed [61, 62], thereby delaying the decoupling of the CMB photons and distorting the pattern of CMB anisotropies.”
The Simons Observatory: science goals and forecasts (2018, background): “To date, the CMB has opened a valuable window into some of these interactions through the limits on dark matter annihilation (Padmanabhan and Finkbeiner 2005).”
WIMP dark matter candidates and searches—current status and future prospects (2017, background): “Other stringent limits come from possible deviations from a standard recombination history caused by DM-induced cascades of highly energetic particles around this period in the evolution of the Universe [275].”
Reionization and the Cosmic Dawn with the Square Kilometre Array (2012, methodology): “The alteration of the ionization state of the IGM may be seen through the CMB cross-correlation power spectra (Padmanabhan & Finkbeiner 2005; Mapelli et al. 2006), and the forthcoming PLANCK data may show hints of, or rule out low mass DM particles self-annihilating with cross sections at the level…”
Phases of new physics in the CMB (2015, methodology): “Alternatively, recombination is very sensitive to energy injection [6] which can alter the form of the visibility function.”