199 research outputs found
Updated galactic radio constraints on Dark Matter
We perform a detailed analysis of the synchrotron signals produced by Dark
Matter annihilations and decays. We consider different set-ups for the
propagation of electrons and positrons, the galactic magnetic field and Dark
Matter properties. We then confront these signals with radio and microwave
maps, including Planck measurements, from a frequency of 22 MHz up to 70 GHz.
We derive two sets of constraints: conservative and progressive, the latter
based on a modeling of the astrophysical emission. Radio and microwave
constraints are complementary to those obtained with other indirect detection
methods, especially for dark matter annihilating into leptonic channels.Comment: 20 pages, 10 figures. v2: some small additions, matches journal
versio
Gamma-Rays from Dark Matter Mini-Spikes in M31
The existence of a population of wandering Intermediate Mass Black Holes
(IMBHs) is a generic prediction of scenarios that seek to explain the formation
of Supermassive Black Holes in terms of growth from massive seeds. The growth
of IMBHs may lead to the formation of DM overdensities called "mini-spikes",
recently proposed as ideal targets for indirect DM searches. Current
ground-based gamma-ray experiments, however, cannot search for these objects
due to their limited field of view, and it might be challenging to discriminate
mini-spikes in the Milky Way from the many astrophysical sources that GLAST is
expected to observe. We show here that gamma-ray experiments can effectively
search for IMBHs in the nearby Andromeda galaxy (also known as M31), where
mini-spikes would appear as a distribution of point-sources, isotropically
distributed in a \thickapprox 3^{\circ} circle around the galactic center. For
a neutralino-like DM candidate with a mass m_{\chi}=150 GeV, up to 20 sources
would be detected with GLAST (at 5\sigma, in 2 months). With Air Cherenkov
Telescopes such as MAGIC and VERITAS, up to 10 sources might be detected,
provided that the mass of neutralino is in the TeV range or above.Comment: 9 pages, 5 figure
Connecting neutrino physics with dark matter
The origin of neutrino masses and the nature of dark matter are two of the
most pressing open questions of the modern astro-particle physics. We consider
here the possibility that these two problems are related, and review some
theoretical scenarios which offer common solutions. A simple possibility is
that the dark matter particle emerges in minimal realizations of the see-saw
mechanism, like in the majoron and sterile neutrino scenarios. We present the
theoretical motivation for both models and discuss their phenomenology,
confronting the predictions of these scenarios with cosmological and
astrophysical observations. Finally, we discuss the possibility that the
stability of dark matter originates from a flavour symmetry of the leptonic
sector. We review a proposal based on an A_4 flavour symmetry.Comment: 21 pages, 4 figures. Review prepared for the focus issue on "Neutrino
Physics". Matches published versio
PPPC 4 DM secondary: A Poor Particle Physicist Cookbook for secondary radiation from Dark Matter
We enlarge the set of recipes and ingredients at disposal of any poor
particle physicist eager to cook up signatures from weak-scale Dark Matter
models by computing two secondary emissions due to DM particles annihilating or
decaying in the galactic halo, namely the radio signals from synchrotron
emission and the gamma rays from bremsstrahlung. We consider several magnetic
field configurations and propagation scenarios for electrons and positrons. We
also provide an improved energy loss function for electrons and positrons in
the Galaxy, including synchrotron losses in the different configurations,
bremsstrahlung losses, ionization losses and Inverse Compton losses with an
updated InterStellar Radiation Field.Comment: 25 pages, many figures. v2: a small clarification on the use of
custom galactic magnetic fields added, matches version published on JCAP. All
results are available at http://www.marcocirelli.net/PPPC4DMID.htm
Detecting the Stimulated Decay of Axions at Radio Frequencies
Assuming axion-like particles account for the entirety of the dark matter in
the Universe, we study the possibility of detecting their decay into photons at
radio frequencies. We discuss different astrophysical targets, such as dwarf
spheroidal galaxies, the Galactic Center and halo, and galaxy clusters. The
presence of an ambient radiation field leads to a stimulated enhancement of the
decay rate; depending on the environment and the mass of the axion, the effect
of stimulated emission may amplify the photon flux by serval orders of
magnitude. For axion-photon couplings allowed by astrophysical and laboratory
constraints(and possibly favored by stellar cooling), we find the signal to be
within the reach of next-generation radio telescopes such as the Square
Kilometer Array.Comment: Minor changes, references added, matches published versio
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