Multi-wavelength emissions from dark matter annihilation processes in galaxy clusters using cosmological simulations
Date
2017
Authors
Mekuria, Remudin Reshid
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Abstract
Based on the Marenostrum-MultiDark Simulation of galaxy Clusters (MUSIC) we develop
semi-analytical models which provide multi-wavelength emission maps generated
by dark matter (DM) annihilation processes in galaxy clusters and their sub-halos. We
focus on radio and gamma-ray emission maps from neutralino DM annihilation processes
testing two different neutralino masses, Mx = 35 GeV and 60 GeV along with two different
models of the magnetic elds. A comparison of the radio
ux densities from our
DM annihilation model with the observed difuse radio emission from the Coma cluster
shows that they are of the same order of magnitude. We determine the DM densities
with a Smoothed Particle Hydrodynamics (SPH) kernel. This enables us to integrate the
DM annihilation signal along any given line-of-sight through the volume of the cluster.
In particular it allows us to investigate the contribution of sub-halos to the DM annihilation
signal with very high resolution. Zooming in on a subset of high mass-to-light ratio
(M/L) DM sub-halos, i.e. DM sub-halos with very low baryon content, we demonstrate
that such targets can generate prominent annihilation signals. The radial distribution
of high M/L DM sub-halos is more strongly peaked at R200crit = 1 compared to the distribution
of all sub-halos which may suggest that the search for DM annihilation signals
from sub-halos in clusters is most promising at R200crit. The radio
ux densities from
DM sub-halos are well within the sensitivity limit of the Square Kilometer Array (SKA)
with an integration time of 1000 hours, and unlike clusters their gamma-ray spectrum
is seen to be dominated by pion decay over a wide range of gamma-ray energies. Our
model makes clear predictions for future radio and gamma-ray observations of the DM
annihilation signals in clusters and their sub-halos.
Description
A thesis submitted in ful lment of the requirements
for the degree of Doctor of Philosophy
in the School of Physics
July 2017.
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Citation
Mekuria, Remudin Reshid (2017) Multi-wavelength emissions from dark matter annihilation processes in galaxy clusters using cosmological simulations, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/25111>