scholarly journals Cosmological boost factor for dark matter annihilation at redshifts of z=10−100 using the power spectrum approach

2021 ◽  
Vol 104 (10) ◽  
Author(s):  
Ryuichi Takahashi ◽  
Kazunori Kohri
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Dark Matter Annihilation ◽  
Boost Factor

scholarly journals The gamma-ray spectral feature from Kaluza–Klein dark matter annihilation and its observability

2017 ◽  
Vol 27 (01) ◽  
pp. 1750187 ◽  
Author(s):  
Satoshi Tsuchida ◽  
Masaki Mori
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Galactic Halo ◽  
Spectral Feature ◽  
High Energy ◽  
Dark Matter Annihilation ◽  
Peak Structure ◽  
Boost Factor ◽  
Near Future ◽  
Kaluza Klein

The theory of universal extra dimensions involves Kaluza–Klein (KK) particles. The lightest KK particle (LKP) is one of the good candidates for cold dark matter. Annihilation of LKP dark matter in the Galactic halo produces high-energy gamma-rays. The gamma-ray spectrum shows a characteristic peak structure around the LKP mass. This paper investigates the observability of this peak structure by near-future detectors taking account of their energy resolution and calculates the expected energy spectrum of the gamma-ray signal. Then, by using the High-Energy Stereoscopic System (HESS) data, we set some constraints on the boost factor, which is a product of the annihilation cross-section relative to the thermal one and an uncertain factor dependent on the substructure of the LKP distribution in the Galactic halo, for each LKP mass. The resulting upper limit on the boost factor is in the range from 1 to 30. The constraints can be regarded as comparable with the results of previous work for gamma-ray and electron–positron observation. However, the observational data for the TeV or higher energy region are still limited, and the possible LKP signal is not conclusive. Thus, we expect near-future missions with better sensitivity will clarify whether the LKP dark matter should exist or not.

scholarly journals DARK MATTER ANNIHILATION EXPLANATION FOR e± EXCESSES IN COSMIC RAY

2009 ◽  
Vol 24 (27) ◽  
pp. 2139-2160 ◽  
Author(s):  
XIAO-GANG HE
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Cosmic Ray ◽  
Proton Spectrum ◽  
Annihilation Rate ◽  
Dark Matter Annihilation ◽  
Data Set ◽  
Boost Factor ◽  
Physics Model ◽  
Correct Data

Recently data from PAMELA, ATIC, FERMI-LAT and HESS show that there are e± excesses in the cosmic ray energy spectrum. PAMELA shown excesses only in e+, but not in anti-proton spectrum. ATIC, FERMI-LAT and HESS shown excesses in e++e- spectrum, but the detailed shapes are different which requires future experimental observations to pin down the correct data set. Nevertheless a lot of efforts have been made to explain the observed e± excesses, and also why PAMELA only has excesses in e+ but not in anti-proton. In this brief review we discuss one of the most popular mechanisms to explain the data — the dark matter annihilation. It has long been known that about 23% of our universe is made of relic dark matter. If the relic dark matter was thermally produced, the annihilation rate is constrained resulting in the need of a large boost factor to explain the data. We will discuss in detail how a large boost factor can be obtained by the Sommerfeld and Breit–Wigner enhancement mechanisms. Some implications for particle physics model buildings will also be discussed.

scholarly journals The 21-cm signals from ultracompact minihaloes as a probe of primordial small-scale fluctuations

2020 ◽  
Vol 494 (3) ◽  
pp. 4334-4342 ◽  
Author(s):  
Kunihiko Furugori ◽  
Katsuya T Abe ◽  
Toshiyuki Tanaka ◽  
Daiki Hashimoto ◽  
Hiroyuki Tashiro ◽  
...  
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Gamma Rays ◽  
Dark Matter Particle ◽  
Density Fluctuations ◽  
Small Scale ◽  
Particle Model ◽  
Dark Matter Annihilation ◽  
Small Scales ◽  
The One

ABSTRACT Ultracompact minihaloes (UCMHs) can form after the epoch of matter–radiation equality, if the density fluctuations of dark matter have significantly large amplitude on small scales. The constraint on the UCMH abundance allows us to access such small-scale fluctuations. In this paper, we present that, through the measurement of 21-cm fluctuations before the epoch of reionization, we can obtain a constraint on the UCMH abundance. We calculate the 21-cm signal from UCMHs and show that UCMHs provide the enhancement of the 21-cm fluctuations. We also investigate the constraint on the UCMH abundance and small-scale curvature perturbations. Our results indicate that the upcoming 21-cm observation, the Square Kilometre Array (SKA), provides the constraint on amplitude of primordial curvature power spectrum, ${\cal A}_{\zeta } \lesssim 10^{-6}$ on 100 ≲ k ≲ 1000 Mpc−1. Although it is not stronger than the one from the non-detection of gamma-rays induced by dark matter annihilation in UCMHs, the constraint by the SKA will be important because this constraint is independent of the dark matter particle model.

scholarly journals Constraints on the primordial power spectrum of small scales using the neutrino signals from the dark matter decay

2014 ◽  
Vol 29 (32) ◽  
pp. 1450194 ◽  
Author(s):  
Yupeng Yang
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Gamma Ray ◽  
Neutrino Flux ◽  
Small Scale ◽  
Scale Invariant ◽  
Dark Matter Annihilation ◽  
Primordial Power Spectrum ◽  
Small Scales

Many inflation theories predict that the primordial power spectrum is scale invariant. The amplitude of the power spectrum can be constrained by different observations such as the cosmic microwave background (CMB), Lyman-α, large-scale structures and primordial black holes (PBHs). Although the constraints from the CMB are robust, the corresponding scales are very large (10-4 < k < 1 Mpc -1). For small scales (k > 1 Mpc -1), the research on the PBHs provides much weaker limits. Recently, ultracompact dark matter minihalos (UCMHs) was proposed and it was found that they could be used to constraint the small-scale primordial power spectrum. The limits obtained by the research on the UCMHs are much better than that of PBHs. Most of previous works focus on the dark matter annihilation within the UCMHs, but if the dark matter particles do not annihilate the decay is another important issue. In previous work [Y.-P. Yang, G.-L. Yang and H.-S. Zong, Europhys. Lett.101, 69001 (2013)], we investigated the gamma-ray flux from the UCMHs due to the dark matter decay. In addition to these flux, the neutrinos are usually produced going with the gamma-ray photons especially for the lepton channels. In this work, we studied the neutrino flux from the UCMHs due to the dark matter decay. Finally, we got the constraints on the amplitude of primordial power spectrum of small scales.

scholarly journals Halo Substructure Boosts to the Signatures of Dark Matter Annihilation

Galaxies ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 68 ◽  
Author(s):  
Shin’ichiro Ando ◽  
Tomoaki Ishiyama ◽  
Nagisa Hiroshima
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dynamic Range ◽  
Theoretical Models ◽  
Substantial Contribution ◽  
Annihilation Rate ◽  
Accurate Assessment ◽  
Dark Matter Annihilation ◽  
Order Unity ◽  
Boost Factor

The presence of dark matter substructure will boost the signatures of dark matter annihilation. We review recent progress on estimates of this subhalo boost factor—a ratio of the luminosity from annihilation in the subhalos to that originating the smooth component—based on both numerical N-body simulations and semi-analytic modelings. Since subhalos of all the scales, ranging from the Earth mass (as expected, e.g., the supersymmetric neutralino, a prime candidate for cold dark matter) to galaxies or larger, give substantial contribution to the annihilation rate, it is essential to understand subhalo properties over a large dynamic range of more than twenty orders of magnitude in masses. Even though numerical simulations give the most accurate assessment in resolved regimes, extrapolating the subhalo properties down in sub-grid scales comes with great uncertainties—a straightforward extrapolation yields a very large amount of the subhalo boost factor of ≳100 for galaxy-size halos. Physically motivated theoretical models based on analytic prescriptions such as the extended Press-Schechter formalism and tidal stripping modeling, which are well tested against the simulation results, predict a more modest boost of order unity for the galaxy-size halos. Giving an accurate assessment of the boost factor is essential for indirect dark matter searches and thus, having models calibrated at large ranges of host masses and redshifts, is strongly urged upon.

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