scholarly journals Effects ofp-wave annihilation on the angular power spectrum of extragalactic gamma-rays from dark matter annihilation

2011 ◽  
Vol 84 (7) ◽  
Author(s):  
Sheldon Campbell ◽  
Bhaskar Dutta
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Gamma Rays ◽  
Dark Matter Annihilation ◽  
Angular Power Spectrum

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 Statistical modelling of the cosmological dispersion measure

2021 ◽  
Vol 502 (2) ◽  
pp. 2615-2629
Author(s):  
Ryuichi Takahashi ◽  
Kunihito Ioka ◽  
Asuka Mori ◽  
Koki Funahashi
Keyword(s):  
Dark Matter ◽  
Correlation Function ◽  
Probability Distribution ◽  
Power Spectrum ◽  
Free Electron ◽  
Statistical Modelling ◽  
Dispersion Measure ◽  
Host Galaxies ◽  
Angular Power Spectrum ◽  
Bias Factor

ABSTRACT We have investigated the basic statistics of the cosmological dispersion measure (DM)—such as its mean, variance, probability distribution, angular power spectrum, and correlation function—using the state-of-the-art hydrodynamic simulations, IllustrisTNG300, for the fast radio burst cosmology. To model the DM statistics, we first measured the free-electron abundance and the power spectrum of its spatial fluctuations. The free-electron power spectrum turns out to be consistent with the dark matter power spectrum at large scales, but it is strongly damped at small scales (≲  Mpc) owing to the stellar and active galactic nucleus feedback. The free-electron power spectrum is well modelled using a scale-dependent bias factor (the ratio of its fluctuation amplitude to that of the dark matter). We provide analytical fitting functions for the free-electron abundance and its bias factor. We next constructed mock sky maps of the DM by performing standard ray-tracing simulations with the TNG300 data. The DM statistics are calculated analytically from the fitting functions of the free-electron distribution, which agree well with the simulation results measured from the mock maps. We have also obtained the probability distribution of source redshift for a given DM, which helps in identifying the host galaxies of FRBs from the measured DMs. The angular two-point correlation function of the DM is described by a simple power law, $\xi (\theta) \approx 2400 (\theta /{\rm deg})^{-1} \, {\rm pc}^2 \, {\rm cm}^{-6}$, which we anticipate will be confirmed by future observations when thousands of FRBs are available.

scholarly journals Monochromatic gamma rays from dark matter annihilation to leptons

2015 ◽  
Vol 2015 (8) ◽  
Author(s):  
Adam Coogan ◽  
Stefano Profumo ◽  
William Shepherd
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Dark Matter Annihilation
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