117 research outputs found
Signatures of Dark Matter in Cosmic-Ray Observations
I provide a short review of the current status of indirect dark matter
searches with gamma rays, charged cosmic rays and neutrinos. For each case I
will focus on various excesses reported in the literature which have been
interpreted as possible hints of dark matter, and I will use them as examples
to discuss theoretical aspects and analysis methodologies.Comment: 8 pages, 2 figures, contribution to the proceedings of the 16th TAUP
conference, Sept. 9-13 2019, Toyama, Japa
Novel dark matter constraints from antiprotons in the light of AMS-02
We evaluate dark matter (DM) limits from cosmic-ray antiproton observations
using the recent precise AMS-02 measurements. We properly take into account
cosmic-ray propagation uncertainties fitting at the same time DM and
propagation parameters, and marginalizing over the latter. We find a
significant (~4.5 sigma) indication of a DM signal for DM masses near 80 GeV,
with a hadronic annihilation cross-section close to the thermal value, sigma v
~3e-26 cm3s-1. Intriguingly, this signal is compatible with the DM
interpretation of the Galactic center gamma-ray excess. Confirmation of the
signal will require a more accurate study of the systematic uncertainties,
i.e., the antiproton production cross-section, and modelling of the solar
modulation effect. Interpreting the AMS-02 data in terms of upper limits on
hadronic DM annihilation, we obtain strong constraints excluding a thermal
annihilation cross-section for DM masses below about 50 GeV and in the range
between approximately 150 and 500 GeV, even for conservative propagation
scenarios. Except for the range around 80 GeV, our limits are a factor 4
stronger than the limits from gamma-ray observations of dwarf galaxies.Comment: 6 pages + 3 of supplemental material, 7 figures, 1 tables. Matches
version published on physical review letter
Joint anisotropy and source count constraints on the contribution of blazars to the diffuse gamma-ray background
We place new constraints on the contribution of blazars to the large-scale
isotropic gamma-ray background (IGRB) by jointly analyzing the measured source
count distribution (logN-logS) of blazars and the measured intensity and
anisotropy of the IGRB. We find that these measurements point to a consistent
scenario in which unresolved blazars make less than 20% of the IGRB intensity
at 1-10 GeV while accounting for the majority of the measured anisotropy in
that energy band. These results indicate that the remaining fraction of the
IGRB intensity is made by a component with a low level of intrinsic anisotropy.
We determine upper limits on the anisotropy from non-blazar sources, adopting
the best-fit parameters of the measured source count distribution to calculate
the unresolved blazar anisotropy. In addition, we show that the anisotropy
measurement excludes some recently proposed models of the unresolved blazar
population.Comment: 7 pages, 4 figures. v2: new section (Sec.III) and 2 figures added.
Expanded discussions in the other sections. Results and conclusions
unchanged. New Section III is also a reply to the comment of Harding &
Abazajian arXiv:1204.3870 on this wor
Constraining heavy dark matter with cosmic-ray antiprotons
Cosmic-ray observations provide a powerful probe of dark matter annihilation
in the Galaxy. In this paper we derive constraints on heavy dark matter from
the recent precise AMS-02 antiproton data. We consider all possible
annihilation channels into pairs of standard model particles. Furthermore, we
interpret our results in the context of minimal dark matter, including
higgsino, wino and quintuplet dark matter. We compare the cosmic-ray antiproton
limits to limits from -ray observations of dwarf spheroidal galaxies
and to limits from -ray and -line observations towards the
Galactic center. While the latter limits are highly dependent on the dark
matter density distribution and only exclude a thermal wino for cuspy profiles,
the cosmic-ray limits are more robust, strongly disfavoring the thermal wino
dark matter scenario even for a conservative estimate of systematic
uncertainties.Comment: 14 pages + references, 5 figures; v2: HESS limits added in Fig. 2,
matches published versio
An Updated Tomographic Analysis of the Integrated Sachs-Wolfe Effect and implications for Dark Energy
We derive updated constraints on the Integrated Sachs-Wolfe (ISW) effect
through cross-correlation of the cosmic microwave background with galaxy
surveys. We improve with respect to similar previous analyses in several ways.
First, we use the most recent versions of extragalactic object catalogs: SDSS
DR12 photometric redshift (photo-) and 2MASS Photo- datasets, as well as
employed earlier for ISW, SDSS QSO photo- and NVSS samples. Second, we use
for the first time the WISE~~SuperCOSMOS catalog, which allows us to
perform an all-sky analysis of the ISW up to . Third, thanks to the
use of photo-s, we separate each dataset into different redshift bins,
deriving the cross-correlation in each bin. This last step leads to a
significant improvement in sensitivity. We remove cross-correlation between
catalogs using masks which mutually exclude common regions of the sky. We use
two methods to quantify the significance of the ISW effect. In the first one,
we fix the cosmological model, derive linear galaxy biases of the catalogs, and
then evaluate the significance of the ISW using a single parameter. In the
second approach we perform a global fit of the ISW and of the galaxy biases
varying the cosmological model. We find significances of the ISW in the range
4.7-5.0 thus reaching, for the first time in such an analysis, the
threshold of 5 . Without the redshift tomography we find a significance
of 4.0 , which shows the importance of the binning method.
Finally we use the ISW data to infer constraints on the Dark Energy redshift
evolution and equation of state. We find that the redshift range covered by the
catalogs is still not optimal to derive strong constraints, although this goal
will be likely reached using future datasets such as from Euclid, LSST, and
SKA.Comment: 16 pages, 6 figures, 8 tables, 2 appendices; v2: minor changes,
matches version published in PRD; ISW likelihood code is available within the
new release of MontePython (see arXiv:1804.07261
Probing dark matter annihilation in the Galaxy with antiprotons and gamma rays
A possible hint of dark matter annihilation has been found in Cuoco,
Korsmeier and Kr\"amer (2017) from an analysis of recent cosmic-ray antiproton
data from AMS-02 and taking into account cosmic-ray propagation uncertainties
by fitting at the same time dark matter and propagation parameters. Here, we
extend this analysis to a wider class of annihilation channels. We find
consistent hints of a dark matter signal with an annihilation cross-section
close to the thermal value and with masses in range between 40 and 130 GeV
depending on the annihilation channel. Furthermore, we investigate in how far
the possible signal is compatible with the Galactic center gamma-ray excess and
recent observation of dwarf satellite galaxies by performing a joint global fit
including uncertainties in the dark matter density profile. As an example, we
interpret our results in the framework of the Higgs portal model.Comment: 12 pages + references, 4 figures, v2: References added, minor changes
in presentation, matches journal versio
A global fit of the -ray galactic center excess within the scalar singlet Higgs portal model
We analyse the excess in the -ray emission from the center of our
galaxy observed by Fermi-LAT in terms of dark matter annihilation within the
scalar Higgs portal model. In particular, we include the astrophysical
uncertainties from the dark matter distribution and allow for unspecified
additional dark matter components. We demonstrate through a detailed numerical
fit that the strength and shape of the -ray spectrum can indeed be
described by the model in various regions of dark matter masses and couplings.
Constraints from invisible Higgs decays, direct dark matter searches, indirect
searches in dwarf galaxies and for -ray lines, and constraints from the
dark matter relic density reduce the parameter space to dark matter masses near
the Higgs resonance. We find two viable regions: one where the Higgs-dark
matter coupling is of , and an additional dark matter
component beyond the scalar WIMP of our model is preferred, and one region
where the Higgs-dark matter coupling may be significantly smaller, but where
the scalar WIMP constitutes a significant fraction or even all of dark matter.
Both viable regions are hard to probe in future direct detection and collider
experiments.Comment: 20 pages + references, 12 figures; v2: minor changes in presentation,
references added, improved scan coverage and updated plots in figs. 6, 8, 9,
10 and 12 accordingly, conclusions unchanged, matches journal versio
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