Constraints on small-scale cosmological perturbations from gamma-ray searches for dark matter

Abstract

Events like inflation or phase transitions can produce large density perturbations on very small scales in the early Universe. Probes of small scales are therefore useful for e.g. discriminating between inflationary models. Until recently, the only such constraint came from non-observation of primordial black holes (PBHs), associated with the largest perturbations. Moderate-amplitude perturbations can collapse shortly after matter-radiation equality to form ultracompact minihalos (UCMHs) of dark matter, in far greater abundance than PBHs. If dark matter self-annihilates, UCMHs become excellent targets for indirect detection. Here we discuss the gamma-ray fluxes expected from UCMHs, the prospects of observing them with gamma-ray telescopes, and limits upon the primordial power spectrum derived from their non-observation by the Fermi Large Area Space Telescope.

4 pages, 3 figures. To appear in J Phys Conf Series (Proceedings of TAUP 2011, Munich)

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Cited by in corpus (5)

• Calculating the mass spectrum of primordial black holes
• Observable Spectra of Induced Gravitational Waves from Inflation
• Reheating the Universe Once More: The Dissipation of Acoustic Waves as a Novel Probe of Primordial Inhomogeneities on Even Smaller Scales
• Observational Constraints on the Primordial Curvature Power Spectrum
• Fingerprints of Anomalous Primordial Universe on the Abundance of Large Scale Structures