731 research outputs found
Directional detection of Dark Matter
Among the many experimental techniques available, those providing directional
information have the potential of yielding an unambiguous observation of WIMPs
even in the presence of insidious backgrounds. A measurement of the
distribution of arrival direction of WIMPs can also discriminate between
Galactic Dark Matter halo models. In this article, I will discuss the
motivation for directional detectors and review the experimental techniques
used by the various experiments. I will then describe one of them, the DMTPC
detector, in more detail.Comment: 17 pages, 11 postscript figures, mini-review submitted to Modern
Physics Letters A (MPLA). Submitted to Modern Physics Letters A (MPLA
GET A GRIP: A graduate student research information portal, program, and plan. Presentation, Great Lakes Science Boot Camp.
Neutrinos in IceCube/KM3NeT as probes of Dark Matter Substructures in Galaxy Clusters
Galaxy clusters are one of the most promising candidate sites for dark matter
annihilation. We focus on dark matter with mass in the range 10 GeV - 100 TeV
annihilating to muon pairs, neutrino pairs, top pairs, or two neutrino pairs,
and forecast the expected sensitivity to the annihilation cross section into
these channels by observing galaxy clusters at IceCube/KM3NeT. Optimistically,
the presence of dark matter substructures in galaxy clusters is predicted to
enhance the signal by 2-3 orders of magnitude over the contribution from the
smooth component of the dark matter distribution. Optimizing for the angular
size of the region of interest for galaxy clusters, the sensitivity to the
annihilation cross section of heavy DM with mass in the range 300 GeV - 100 TeV
will be of the order of 10^{-24} cm^3 s^{-1}, for full IceCube/KM3NeT live time
of 10 years, which is about one order of magnitude better than the best limit
that can be obtained by observing the Milky Way halo. We find that neutrinos
from cosmic ray interactions in the galaxy cluster, in addition to the
atmospheric neutrinos, are a source of background. We show that significant
improvement in the experimental sensitivity can be achieved for lower DM masses
in the range 10 GeV - 300 GeV if neutrino-induced cascades can be reconstructed
to approximately 5 degrees accuracy, as may be possible in KM3NeT. We therefore
propose that a low-energy extension "KM3NeT-Core", similar to DeepCore in
IceCube, be considered for an extended reach at low DM masses.Comment: v2: 17 pages, 5 figures. Neutrino spectra corrected, dependence on
dark matter substructure model included, references added. Results unchanged.
Accepted in PR
Inert-Sterile Neutrino: Cold or Warm Dark Matter Candidate
In usual particle models, sterile neutrinos can account for the dark matter
of the Universe only if they have masses in the keV range and are warm dark
matter. Stringent cosmological and astrophysical bounds, in particular imposed
by X-ray observations, apply to them. We point out that in a particular
variation of the inert doublet model, sterile neutrinos can account for the
dark matter in the Universe and may be either cold or warm dark matter
candidates, even for masses much larger than the keV range. These Inert-Sterile
neutrinos, produced non-thermally in the early Universe, would be stable and
have very small couplings to Standard Model particles, rendering very difficult
their detection in either direct or indirect dark matter searches. They could
be, in principle, revealed in colliders by discovering other particles in the
model.Comment: 10 pages, 5 figures; version 2: small changes in the text and
references adde
Bound on the Dark Matter Density in the Solar System from Planetary Motions
High precision planet orbital data extracted from direct observation,
spacecraft explorations and laser ranging techniques enable to put a strong
constraint on the maximal dark matter density of a spherical halo centered
around the Sun. The maximal density at Earth's location is of the order
and shows only a mild dependence on the slope of the halo
profile, taken between 0 and -2. This bound is somewhat better than that
obtained from the perihelion precession limits.Comment: 7 pages, 1 figur
Cosmological Parameters from Observations of Galaxy Clusters
Studies of galaxy clusters have proved crucial in helping to establish the
standard model of cosmology, with a universe dominated by dark matter and dark
energy. A theoretical basis that describes clusters as massive,
multi-component, quasi-equilibrium systems is growing in its capability to
interpret multi-wavelength observations of expanding scope and sensitivity. We
review current cosmological results, including contributions to fundamental
physics, obtained from observations of galaxy clusters. These results are
consistent with and complementary to those from other methods. We highlight
several areas of opportunity for the next few years, and emphasize the need for
accurate modeling of survey selection and sources of systematic error.
Capitalizing on these opportunities will require a multi-wavelength approach
and the application of rigorous statistical frameworks, utilizing the combined
strengths of observers, simulators and theorists.Comment: 53 pages, 21 figures. To appear in Annual Review of Astronomy &
Astrophysic
Catalogue of Galaxies and of Clusters of Galaxies
Covering the Palomar survey fields of the declination zones +60°, +66°, +72°, +78°, +84°, +90°
The present rate of Supernovae
We present and discuss the most recent determination of the rate of
Supernovae in the local Universe. A comparison with other results shows a
general agreement on the gross values but still significant differences on the
values of the rates of various SN rates in different kinds of galaxies. The
rate of SNe, used as a probe of Star Formation, confirms the young progenitor
scenario for SNII+Ib/c. The increasing diversity of SNe reflects also in the SN
yields which may affect the chemical evolution of the Galaxy but, because of
the limited statistics, we cannot estimate the contributions of the new
subtypes yet. It is also expected that in a few years observational
determinations of the SN rates at various look-back times will be available.Comment: 9 pages, Latex, 1 figure, To appear in the proceedings of the
conference "The Chemical Evolution of The Milky Way: Stars versus Clusters",
eds. F. Matteucci and F. Giovannelli, Vulcano, Italy, September 20-24 199
Catalogue of Galaxies and of Clusters of Galaxies
Covering the Palomar survey fields
of the declination zones +36°, +42°, +48°, +54°
between 5^h30^m and 20^h00^m in right ascension
- …