| arXiv:0802.3530 [ps, pdf, other]
Title:
A Search for WIMPs with
the First Five-Tower Data from CDMS
Authors:
CDMS
CollaborationWe report first results from the
Cryogenic Dark Matter Search (CDMS II) experiment running with
its full complement of 30 cryogenic particle detectors at the
Soudan Underground Laboratory. This report is based on the
analysis of data from 15 Ge detectors (3.75 kg) acquired
between October 2006 and July 2007 for an effective exposure
of 121.3 kg-d (averaged over recoil energies 10--100 keV,
weighted for a weakly interacting massive particle (WIMP) mass
of 60 GeV/c^2). A blind analysis, incorporating improved
techniques for rejecting surface events and estimating
background leakage into the signal region, resulted in zero
observed events. This analysis sets an upper limit on the
WIMP-nucleon spin-independent cross section of 6.6x10^{-44}
cm^2 (4.6x10^{-44} cm^2 when combined with previous CDMS data)
at the 90% confidence level for a WIMP mass of 60 GeV/c^2. By
excluding new parameter space for WIMP dark matter with masses
above 42 GeV/c^2 this work significantly restricts some of the
favored supersymmetric models. |
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arXiv:0802.3245 [ps, pdf, other]:
Title:
Optimal angular window
for observing Dark Matter annihilation from the Galactic
Center region: the case of gamma-ray lines
Although the emission of
radiation from dark matter annihilation is expected to be
maximized at the Galactic Center, geometric factors and the
presence of point-like and diffuse backgrounds make the choice
of the angular window size to optimize the chance of a signal
detection a non-trivial problem. Contrarily to what is often
assumed, we find that the best strategy is to focus on a
window size around the Galactic Center of ~ 1 deg to >~ 30
deg, where the optimal size depends on the angular
distribution of the signal and the backgrounds. Although our
conclusions are general, we illustrate this point in the
particular case of annihilation into two monochromatic photons
in the phenomenologically most interesting range of energy 45
GeV < E < 80 GeV, which is of great interest for the
GLAST satellite. We find for example that Dark Matter models
with sufficiently strong line annihilation signals, like the
Inert Doublet Model, may be detectable without or with very
moderate boost factors.
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|
arXiv:0802.3239 [ps, pdf, other] :
Title:
First Detection of
Cosmic Structure in the 21-cm Intensity Field
Authors: Ue-Li
Pen, Lister
Staveley-Smith, Jeffrey
Peterson, Tzu-Ching
Chang
We present the first statistically
significant detection of cosmic structure using broadly
distributed hydrogen radio emission. This is accomplished
using a cross correlation with optical galaxies. Statistical
noise levels of $20 \mu $K are achieved, unprecedented in this
frequency band. This lends support to the idea that large
volumes of the universe can be rapidly mapped without the need
to resolve individual faint galaxies, enabling precise
constraints to dark energy models. We discuss strategies for
improved intensity mapping.
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New PAMELA results
Presentation
by Piergiorgo Picozza at the 8th UCLA Symposium Sources and Dectection of Dark
Matter and Dark Energy in the Universe, February
20th-22nd, Marina del Rey, CA
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Authors: Ilias
Cholis, Lisa
Goodenough, Neal
Weiner (CCPP, NYU) We consider the signals of positrons
and electrons from ``exciting'' dark matter (XDM) annihilation.
Because of the light (m_phi < 1 GeV) force carrier phi into which
the dark matter states can annihilate, the electrons and positrons
are generally very boosted, yielding a hard spectrum, in addition to
the low energy positrons needed for INTEGRAL observations of the
galactic center. We consider the relevance of this scenario for
HEAT, PAMELA and the WMAP ``haze,'' focusing on light (m_phi < 2
m_pi) phi bosons, and find that significant signals can be found for
all three, without resorting to significant ``boost'' factors
arising from clumpiness of the halo. We find that measurements of
the positron fraction are generally insensitive to the halo model,
but do suffer significant astrophysical uncertainties. We discuss
the implications for upcoming PAMELA results.
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- arXiv:0802.3830
[ps, pdf, other]
- Title: WMAP Haze: Directly Observing
Dark Matter?
- Authors: Michael
McNeil Forbes, Ariel
R. Zhitnitsky
- In this paper we show that dark matter in the form of
dense matter/antimatter nuggets could provide a natural and
unified explanation for several distinct bands of diffuse
radiation from the core of the galaxy spanning over 13
orders of magnitude in frequency. We fix all of the
phenomenological properties of this model by matching to
X-ray observations in the keV band, and then calculate the
unambiguously predicted thermal emission in the microwave
band, at frequencies smaller by 11 orders of magnitude.
Remarkably, the intensity and spectrum of the emitted
thermal radiation are consistent with - and could entirely
explain - the so-called "WMAP haze'': a diffuse microwave
excess observed from the core of our galaxy. This provides
another strong constraint of our proposal, and a remarkable
non-trivial validation. If correct, our proposal identifies
the nature of the dark matter, explains baryogenesis, and
provides a means to directly probe the matter distribution
in our Galaxy by analyzing several different types of
diffuse emissions.
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arXiv:0802.3453 [ps, pdf, other]
Title:
Galactic rotation curves and
brane world models
In the present investigation flat
rotational curves of the galaxies are considered under the
framework of brane-world models where the 4d effective
Einstein equation has extra terms which arise from the
embedding of the 3-brane in the $5d$ bulk. It has been shown
here that these long range bulk gravitational degrees of
freedom can act as a mechanism to yield the observed galactic
rotation curves without the need for dark matter. The present
model has the advantage that the observed rotation curves
result solely from well-established non-local effects of
gravitation, such as dark radiation and dark pressure under a
direct use of the condition of flat rotation curves and does
not invoke any exotic matter field. | |
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