76 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
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
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
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
Gamma ray tests of Minimal Dark Matter
We reconsider the model of Minimal Dark Matter (a fermionic, hypercharge-less
quintuplet of the EW interactions) and compute its gamma ray signatures. We
compare them with a number of gamma ray probes: the galactic halo diffuse
measurements, the galactic center line searches and recent dwarf galaxies
observations. We find that the original minimal model, whose mass is fixed at
9.4 TeV by the relic abundance requirement, is constrained by the line searches
from the Galactic Center: it is ruled out if the Milky Way possesses a cuspy
profile such as NFW but it is still allowed if it has a cored one. Observations
of dwarf spheroidal galaxies are also relevant (in particular searches for
lines), and ongoing astrophysical progresses on these systems have the
potential to eventually rule out the model. We also explore a wider mass range,
which applies to the case in which the relic abundance requirement is relaxed.
Most of our results can be safely extended to the larger class of multi-TeV
WIMP DM annihilating into massive gauge bosons.Comment: 25 pages, 8 figures. v2: a few comments and references added, matches
version published on JCA
Antiproton constraints on the GeV gamma-ray excess: a comprehensive analysis
A GeV gamma-ray excess has possibly been individuated in Fermi-LAT data from
the Galactic Center and interpreted in terms of Dark Matter (DM) annihilations,
either in hadronic (essentially ) or leptonic channels. In order to
test this tantalizing interpretation, we address two issues: (i) we improve the
computation of secondary emission from DM (Inverse Compton and Bremsstrahlung)
with respect to previous works, confirming it to be very relevant for
determining the DM spectrum in the leptonic channels, so that any conclusion on
the DM nature of the signal critically depends on this contribution; (ii) we
consider the constraints from antiprotons on the DM hadronic channel, finding
that the uncertainties on the propagation model, and in particular on the halo
height, play a major role. Moreover, we discuss the role of solar modulation,
taking into account possible charge dependent effects whose importance is
estimated exploiting detailed numerical tools. The limits that we obtain
severely constrain the DM interpretation of the excess in the hadronic channel,
for standard assumptions on the Galactic propagation parameters and solar
modulation. However, they considerably relax if more conservative choices are
adopted.Comment: 22 pages, 6 figures, 2 table
Probing light dark scalars with future experiments
We investigate a dark sector containing a pair of light non-degenerate scalar
particles, with masses in the MeV-GeV range, coupled to the visible sector
through heavier mediators. The heaviest dark state is long-lived, and its
decays offer new testable signals. We analyze the prospects for detection with
the proposed beam-dump facility SHiP, and the proposed LHC experiments FASER
and MATHUSLA. Moreover, we consider bounds from the beam-dump experiment CHARM
and from colliders (LEP, LHC and BaBar). We present our results both in terms
of an effective field theory, where the heavy mediators have been integrated
out, and of a simplified model containing a vector boson mediator, which can be
heavy TeV, or light GeV. We show that
future experiments can test large portions of the parameter space currently
unexplored, and that they are complementary to future High-Luminosity LHC
searches.Comment: 25 pages, 2 appendices, 6 figures. v2: version accepted for
publication. Several clarifications added, Figs. 3-5 modified to take into
account the heaviest state decay length. Conclusions unchange
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