Dark Matter Decay and the Abundance of Ultracompact Minihalos

Abstract

Ultracompact minihalos would be formed if there are larger density perturbations ($0.0003<\delta \rho /\rho <0.3$) in the earlier epoch. The density profile of them is steeper than the standard dark matter halos. If the dark matter can annihilate or decay into the standard particles, e.g., photons, these objects would be the potential astrophysical sources. In order to be consistent with the observations, such as $Fermi$, the abundance of ultracompact minihalos must be constrained. On the other hand, the formation of these objects has very tight relation with the primordial curvature perturbations on smaller scale, so the fraction of ultracompact minihalos is very important for modern cosmology. In previous works, the studies are focused on the dark matter annihilation for these objects. But if the dark matter is not annihilated, the dark matter decay is another important possible case. On the other hand, the abundance of ultracompact minihalos is related to many other parameters, such as the mass of dark matter, the decay channels and the density profile of dark matter halo. One of the important aspects of this work is that we investigate the $\gamma$-ray signals from nearby ultracompact minihalos due to dark matter decay and another important aspect is to study in detail how the different decay channels and density profiles affect the constraints on the abundance of ultracompact minihalos.

11 pages, 4 figures, 1 table. Comments Welcome!! Some presentations are improved and added, figures are replotted according to the referees' suggestion. The constraints on the primordial curvature perturbations are also given. Accepted for publication in EPL

References in corpus (7)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Contraints on radiative dark-matter decay from the cosmic microwave background
• Gamma ray constraints on Decaying Dark Matter
• Gamma-Rays from Decaying Dark Matter
• Gamma-rays from ultracompact minihalos: potential constraints on the primordial curvature perturbation
• Superdense cosmological dark matter clumps
• Annihilations of superheavy dark matter in superdense clumps

Cited by in corpus (16)

• Density profiles of ultracompact minihalos: Implications for constraining the primordial power spectrum
• Small-scale clumps of dark matter
• Are ultracompact minihalos really ultracompact?
• Formation and internal structure of superdense dark matter clumps and ultracompact minihaloes
• Investigating dark matter substructure with pulsar timing: I. Constraints on ultracompact minihalos
• 3D simulations with boosted primordial power spectra and ultracompact minihalos
• Number Counts and Non-Gaussianity
• Predicting the density profiles of the first halos
• Neutrino signals from ultracompact minihalos and constraints on the primordial curvature perturbation
• Investigating dark matter substructure with pulsar timing: II. Improved limits on small-scale cosmology
• Constraints on primordial black holes and curvature perturbations from the global 21cm signal
• Hunting for dark halo substructure using submilliarcsecond-scale observations of macrolensed radio jets
• The abundance of primordial black holes from the global 21cm signal and extragalactic gamma-ray background
• Constraints on cosmic strings from ultracompact minihalos
• Constraints on the primordial power spectrum of small scales using the neutrino signals from the dark matter decay
• Constraints on the ultracompact minihalos using neutrino signals from the gravitino dark matter decay