Cosmological boost factor for dark matter annihilation at redshifts of $z=10$-$100$ using the power spectrum approach

Abstract

We compute the cosmological boost factor at high redshifts of $z=10$-$100$ by integrating the non-linear matter power spectrum measured from high-resolution cosmological $N$-body simulations. An accurate boost factor is required to estimate the energy injection from dark matter annihilation, which may affect the cosmological re-ionization process. We combined various box-size simulations (side lengths of $1\mathrm{kpc}$-$10\mathrm{Mpc}$) to cover a wide range of scales, i.e. $k=1$-$10^7{\mathrm{Mpc}}^{-1}$. The boost factor is consistent with the linear theory prediction at $z\gtrsim 50$ but strongly enhanced at $z\lesssim 40$ as a result of non-linear matter clustering. Although dark matter free-streaming damping was imposed at $k_{\mathrm{fs}}=10^6{\mathrm{Mpc}}^{-1}$ in the initial power spectrum, the damping disappears at later times of $z\lesssim 40$ as a result of the power transfer from large to small scales. Because the simulations do not explore very small-scale clustering at $k>10^7{\mathrm{Mpc}}^{-1}$, our result is a lower bound on the boost factor at $z\lesssim 40$. A simple fitting function of the boost factor is also presented.

12 pages, 5 figures, accepted for publication in PRD

References in corpus (11)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Transients from Initial Conditions in Cosmological Simulations
• A blueprint for detecting supersymmetric dark matter in the Galactic halo
• Discreteness effects in simulations of Hot/Warm dark matter
• Separate Universe Simulations
• Hierarchical Formation of Dark Matter Halos and the Free Streaming Scale
• Unveiling the nature of dark matter with high redshift 21 cm line experiments
• The nature of dark matter from the global high redshift HI 21 cm signal
• Cross-Correlation of Cosmic Shear and Extragalactic Gamma-ray Background: Constraints on the Dark Matter Annihilation Cross-Section
• Cosmological simulation in tides: power spectra and halo shape responses, and shape assembly bias
• Anisotropic separate universe simulations

Cited by in corpus (4)

• Minihalos as probes of the inflationary spectrum: accurate boost factor calculation and new CMB constraints
• Prospects for probing dark matter particles and primordial black holes with the Hongmeng mission using the 21 cm global spectrum at cosmic dawn
• Global signal in the redshifted hydrogen 21-cm line from the Dark Ages and Cosmic Dawn: Dependence on the nature of dark matter and modeling of first light
• Enhanced Small-Scale Structure in the Cosmic Dark Ages