Speaker
Institution
Title
Abstract |
Tareq AbuZayyad
U. of Utah
Cross-checks of the HiRes
Monocular Flux Measurements
The HiRes Collaboration has published results on the flux of the
ultra-high energy cosmic rays, based on monocular observation by the
two sites comprising the stereo detector. The main advantage of
stereo observation is the superior geometrical reconstruction as
compared with monocular reconstructed tracks. A combined analysis of
the two monocular data sets makes it possible to use stereo
reconstructed shower track geometry as the input to the monocular
analysis for each site now with the benefit of accurate geometrical
reconstruction. Results will be presented.
|
Speaker
Institution
Title
Abstract
|
Felix Aharonian
Max Planck Institut fuer
Kernphysik
TeV Gamma Rays and Origin
of Cosmic Rays
I will discuss the objectives of Very High Energy
Gamma Ray Astronomy (and practical ways of their realization) relevant
to the solution of the problem of origin of Galactic and Extragalactic
Cosmic Rays.
|
Speaker
Institution
Title
Abstract |
Eun-Joo
Ahn
University of Chicago
Gamma-ray background from
dark
matter annihilations in Spikes
We calculate the gamma ray background from dark matter annihilations in
cosmological
halos. We estimate the importance of "Spikes", i.e. enhancements in the
Dark Matter distribution
around Supermassive black holes lying at the center of galaxies.
|
Speaker
Institution
Title
Abstract |
Ivone Albuquerque
Univ Sao Paulo
Looking for SUSY
in the Ice
It will be shown that neutrino telescopes are potentially sensitive to
long lived charged NLSPs which
are present in a
wide variety of models of supersymmetry breaking. In these models the
LSP is the
gravitino. These
particles are produed by the diffuse flux of neutrinos colliding with
nucleons in the
Earth and can be
observed in large ice or water Cerenkov detectors. The small production
cross
section is
partially compensated by the very long range of sleptons. Using the
Waxman-Bahcall limit
for the neutrino
flux results in up to four events a year in km3 experiments.
|
Speaker
Institution
Title
Abstract |
Luis Anchordoqui
Northeastern University
IceHEP
Because of absorption in traversing the Earth, the simultaneous
consideration of up-coming and
down-going event rates at neutrino telescopes can serve to constrain
both the extraterrestrial neutrino
flux and contributions to the neutrino cross sections from non-standard
model processes. In this
context, we show that if the extraterrestrial neutrino flux is at the
Waxman-Bahcall level, the IceCube
facility will attain an effective integrated luminosity L \approx 25
nb^{-1}, at \sqrt{s} \simeq 6 TeV. Since
at this energy there is negligible background from atmospheric
neutrinos, such a luminosity will allow to
probe 40% (70%) deviations from standard model predictions at the 90%
(99.9%) CL. Should the
neutrino flux be at the level predicted for optically thick blazars,
these bounds can be attained after one
year of data collection at IceCube.
We also show that the recently reported AMANDA-B10 upper limit on the
diffuse neutrino flux provides
in full generality two joint constraints on flux and cross section. As
an interesting application, it is seen
that these can limit the amount of any suppression of the
neutrino-nucleon cross section below
present estimates.
|
Speaker
Institution
Title
Abstract |
Shin'ichiro Ando
University of Tokyo
TeV neutrinos from jets in
core-collapse supernovae
Gamma-ray bursts (GRBs) are rare but powerful explosions displaying
highly relativistic jets. It has
been suggested that a significant fraction of the much more frequent
core-collapse supernovae are
accompanied by comparably energetic but mildly relativistic jets, which
would indicate an underlying
supernova--GRB connection. We calculate the neutrino spectra from the
decays of pions and kaons
produced in jets in supernovae, and show that the kaon contribution is
dominant and provides a sharp
break near 20 TeV, which is a sensitive probe of the conditions inside
the jet. For a supernova at 10
Mpc, 30 events above 100 GeV are expected in a 10 s burst in the
IceCube detector.
|
Speaker
Institution
Title
Abstract |
Howie Baer
Florida State University
Neutralino Dark Matter: Direct,
Indirect and Collider Detection
We explore parameter space regions of various SUSY models with
and without soft term universality. A
number fo rgeions emerge which are consistent with WMAP
measurements. Each of these regions has
distinct prospects for direct and indirect DM detection. We also
show how each region would be
revealed at collider experiments, including the Fermilab
Tevatron, the CERN LHC and the ILC.
|
Speaker
Institution
Title
Abstract |
Csaba Balazs
Argonne National Laboratory
The supersymmetric origin
of matter
Most of the matter in the Universe consists of non-luminous (dark)
matter and baryons, and these two
components usually interpreted independently from each other. In this
talk, I argue that there is a
simple way to relate these components within a unified framework. I
show that the minimal
supersymmetric extension of the standard particle model (the MSSM)
provides a common origin for
both components of matter. I also show that this scenario is not only
feasible but also testable at
present and near future colliders, low energy and dark matter direct
detection experiments in a
complementary way.
|
Speaker
Institution
Title
Abstract |
Edward Baltz
KIPAC
Dark Matter and Data
In the next few years the amount of data pertaining to the dark matter
problem is set to explode.
Underground experiments are already probing the parameter space of
supersymmetric models, the
Large Hadron Collider at CERN will begin operations in 2007 and the
GLAST satellite will launch in the
same year. We discuss how the results of these might interact. If the
LHC discovers a dark matter
candidate, how well can its properties be constrained? Given such a
discovery, can the known dark
matter density be used to improve various of the accelerator
measurements? We argue for the
necessity of the International Linear Collider to answer these and
other key questions. Finally, it will fall
to astrophysics to demonstrate the the galactic halo does in fact
consist of the particles we hope to
discover at the LHC, whether by underground experiments directly
detecting the dark matter particles,
or by detecting the annihilation radiation from the galactic halo. In
particular, we discuss strategies for
searching for the signatures of dark matter annihilations in the GLAST
dataset.
|
|
Dan Bauer
Fermi National Accelerator Laboratory
Direct Detection of Dark
Matter
I would review the current status of direct detection experiments for
dark matter and discuss the
possible approaches for extending these searches in the future.
|
Speaker
Institution
Title
Abstract |
John Beacom
Ohio State U.
Quis custodiet ipsos
custodes? Who will neutrino the neutrinos?
Due to their weak interactions, neutrinos can reveal the physical
conditions otherwise hidden behind great column densities of matter --
whether deep within astrophysical objects, or from across the Universe
itself. But are neutrinos reliable witnesses? Can we trust
them farther than we've thrown them? I will discuss how to use
different detection channels to verify if neutrinos are telling us the
truth about astrophysical sources...and themselves.
|
Speaker
Institution
Title
Abstract |
Konstantin Belov
U. of Utah
Proton-air inelastic
cross-section measurement at ultra-high energies by HiRes stereo
fluorescence cosmic
We used data collected by the HiRes stereo fluorescence detector and a
specially developed measurement technique to measure the proton--air
inelastic cross-section at 10^{18.5} eV. The measured cross--section
value of 456\pm17(stat)+39(sys)-11(sys) mb is in good agreement with
the prediction of interaction models and with extrapolation from
accelerator data. It favours the Froissart bound saturation at
ultra--high energies. The assymetric systematic error takes into
account possible influence of a gamma ray flux at the energies of
interest. We discuss the measurement technique, the result and the
systematic errors. The HiRes detector sensitivity for measuring the
gamma ray flux upper limit is also discussed.
|
Speaker
Institution
Title
Abstract |
Konstantin Belov
U. of Utah
Primary cosmic ray
mass-composition at ultra-high energies measured by HiRes stereo
The HiRes stereo fluorescence detector can accurately measure the
profile of extensive air showers produced by high energy cosmic ray
particles. We measured mass--composition of the primary cosmic rays at
ultra--high energies by using the mean of the air shower maxima
distribution. We found the composition to be slowly changing and
predominantely light. The result is in good agreement with the Fly's
Eye and the HiRes-MIA measurements. The result and the systematic
errors are discussed.
|
Speaker
Institution
Title
Abstract |
Wystan Benbow
Max-Planck-Institut für Kernphysik
H.E.S.S. Performance and
Results
The High Energy Stereoscopic System (H.E.S.S) is an array of four
imaging atmospheric-Cherenkov telescopes located in the Khomas
Highlands of Namibia. The low
energy threshold (~100 GeV), excellent background rejection (>99%),
and good angular resolution
(<0.1 deg) of H.E.S.S. allow the detection of a 1% Crab flux source
in ~25 hours of observation. This
enables H.E.S.S. to perform searches for VHE gamma-ray emission from
astrophysical objects with
unprecedented sensitivity. H.E.S.S. has already detected more than 20
sources of VHE gamma rays,
from a number of source classes. The performance of H.E.S.S. and the
results of recent observations
will be reported here.
|
Speaker
Institution
Title
Abstract |
Hsin-Chia Cheng
Harvard University
Little Higgs Theories and
Dark Matter
Hierarchy problem in the Higgs sector and dark matter are two main
motivations for new physics
beyond the standard model at the TeV scale. Little Higgs theories with
T-parity provides solutions to
both questions. The lightest T-odd particle is a natural dark matter
candidate. I will discuss the
similarities and differences between these theories and other scenarios
such as supersymmetry and
universal extra dimensions.
|
Speaker
Institution
Title
Abstract |
T.
Coarasa
Max-Planck-Institut für Physik
The MAGIC Telescope
Project. Status and Results
The current status of the MAGIC telescope project will be presented.
Recent results will be showed and future plans including the building
of a second telescope of the MAGIC collaboration will be outlined.
|
Speaker
Institution
Title
Abstract |
Johann Cohen-Tanugi
Stanford Linear Accelerator Center
High Energy Astrophysics
with GLAST
I will review the GLAST mission, and the science prospects it offers.
|
Speaker
Institution
Title
Abstract |
Amy Connolly
University of California, Los Angeles
Searching for Ultra High
Energy Neutrinos With ANITA and SalSA
The Antarctic Impulsive Transient Antenna (ANITA) will launch in the
2006-2007 Austrial summer with
the aim to detect neutrinos that are emitted when ultra-high energy
cosmic rays interact with the cosmic
microwave background radiation. ANITA is designed to detect the radio
Cerenkov signal emitted
through the Askaryan effect when neutrinos interact in the Antarctic
ice. The ANITA team successfully
carried out a test flight in Antartica in the 2003-2004 Austral summer
with a payload that included
prototypes of all major components of the experiment, including two
antennas. The Saltdome Shower
Array (SalSA) is a project in the exploratory stage, aiming to measure
a large sample of ultra-high
energy neutrinos so that their properties may provide clues about the
nature of the sources of ultra high
energy particles in the universe and also probe particle physics at
energies that surpass that of the
LHC. I will review the status of each of the two experiments and the
progress that has been made in
building realistic simulations of each detection system.
|
Speaker
Institution
Title
Abstract |
Charles Dermer
US Naval Research Laboratory
TeV Emission from the Galactic
Center Black Hole Plerion
The HESS collaboration reported highly significant detection of
TeV gamma-rays coincident with Sgr
A*. We propose the following model: In the extreme
advection-dominated accretion flow (ADAF)
regime of the GC black hole (BH), synchrotron radio/submillimeter
emission of ~100 MeV electrons
emanates from an inefficiently radiating turbulent magnetized
corona within 20RS (Schwarzschild radii)
of the GCBH. These electrons are accelerated through second-order
Fermi processes by MHD
turbulence. Closer to the innermost stable orbit of the ADAF,
instabilities and shocks within the flow
inject power-law electrons through first-order Fermi acceleration
to make synchrotron X-ray flares
observed with Chandra, XMM, and INTEGRAL. A subrelativistic MHD
wind subtending an ~1 sr cone
with power >~1037 ergs s-1 is driven by the ADAF. As in
pulsar-powered plerions, electrons are
accelerated at the wind termination shock at >~10^16.5 cm from
the GCBH, and Compton-scatter the
ADAF and the far-infrared dust radiation to TeV energies. The
synchrotron radiation of these electrons
forms the quiescent X-ray source resolved by Chandra. The radio
counterpart of this TeV/X-ray plerion,
formed when the injected electrons cool on timescales of >~104
yr, could explain the origin of
nonthermal radio emission in the parsec-scale bar of the radio
nebula Sgr A West.
Work performed in association with Dr. Armen Atoyan (U. de
Montreal).
|
Speaker
Institution
Title
Abstract |
Juerg Diemand
University of California, Santa Cruz
The distribution of cold
dark matter in the Galaxy
Cosmological N-body simulations are revealing the structure of the dark
matter halo of the Milky Way
with ever increasing precision. Over the last two decades the picture
has changed form a smooth halo
with a shallow density profile to a cuspy system with lots of
substructure. The dark matter annihilation
signal for indirect detection is dominated by regions of very high
density which are still difficult to
resolve numerically. The local phase space distribution of CDM relevant
to direct detection experiments
is probablymorecomplicated than the smooth distributions seen in
current N-body halos. I will review
recent progress on these issues and present new results from higher
resolution simulations.
|
Speaker
Institution
Title
Abstract |
Brenda Dingus
Los Alamos National Laboratory
Surveying the TeV Sky with
Milagro
A wide field of view, high duty factor, TeV gamma-ray observatory is
essential for studying TeV
astrophysical sources, because most of these sources are either highly
variable or are extended.
Milagro is such a TeV detector and has performed the deepest survey of
the Northern Hemisphere sky.
In addition to detecting the known TeV sources of the Crab Nebula and
Mrk421, Milagro has made the
first detection of diffuse TeV emission from the Galactic plane. The
Milagro data has been searched for
unknown point sources and extended sources. Evidence for two new
extended TeV sources are
found--one located in the Galactic plane and the other coincident with
an EGRET unidentified source.
The Milagro data has also been searched for the predicted TeV emitters
of gamma-ray bursts, galaxy
clusters, and EGRET unidentified sources. Upper limits on these sources
are constraining predictions.
|
Speaker
Institution
Title
Abstract |
Leanne Duffy
University of Florida
Axion Dark Matter Search
I describe the search conducted by the Axion Dark Matter
eXperiment (ADMX) with the new high
resolution channel. The first data probes the axion mass range
1.98 to 2.17 micro-eV. No axion signal
was found and the search yields new exclusion limits.
|
Speaker
Institution
Title
Abstract |
Francesc Ferrer
Case Western Reserve University
TeV gamma-rays from Dark Matter
annihilations
Ground based Atmospheric Cerenkov Telescopes have recently
unveiled a TeV gamma-ray signal
from the direction of the Galactic Centre. We examine whether
these gamma-rays, observed by the
VERITAS, CANGAROO-II and HESS collaborations, may arise from
annihilations of dark matter
particles. Emission from nearby dwarf spheroidals, such as
Sagittarius, could provide a test of this
scenario.
|
Speaker
Institution
Title
Abstract |
Douglas Finkbeiner
Princeton U.
WMAP Microwave Emission
Interpreted as Dark Matter Annihilation in the Inner Galaxy
Synchrotron emission from a population of ultra-relativistic electrons
in the inner Galaxy has been observed by the Wilkinson Microwave
Anisotropy Probe (WMAP). After careful modeling of the microwave
foreground signals from Galactic interstellar medium a residual
microwave signal is present within 10-20 degrees of the Galactic
center, uncorrelated with any known foreground template. The most
likely explanation for this mysterious component is synchrotron
emission from an unusually hot electron energy distribution. The
source of these electrons is still uncertain, but the spatial
distribution, inferred energy spectrum, and total number are consistent
with their being positron-electron pairs produced by WIMP annihilation.
|
Speaker
Institution
Title
Abstract |
Ayres Freitas
Fermi National Accelerator Laboratory
Light stops: connecting
cosmology with (linear) colliders
Light scalar top quarks provide a framework for explaining
electroweak baryogenesis and the dark
matter relic abundance. The scalar tops contribute to the dark
matter density via the co-annihilation
mechanism when the mass difference between the scalar tops and
the lightest neutralino is small, i.e.
of order 15-20 GeV. The ILC would be an ideal tool for exploring
this scenario. In addition to finding the
existence of light stop quarks, the precise measurement of their
properties is crucial for testing their
impact on the dark matter relic abundance and the mechanism of
electroweak baryogenesis. Based on
the detailed simulations we study the uncertainties for the dark
matter density predictions and their
estimated uncertainties from various sources. Our results show
that the ILC will allow us to deduce
precise information about the role of supersymmetry in the
evolution of the universe.
|
Speaker
Institution
Title
Abstract |
Jennifer Gaskins
U. of Chicago
Detecting Neutralino Dark
Matter in the Large Magellanic Cloud
The neutralino is a popular candidate for a cold dark matter particle.
I will discuss the possibility of detecting neutralino dark matter
through observations of gamma-rays and synchrotron emission produced by
neutralino annihilation. Evidence suggests that satellites of our
galaxy contain substantial amounts of dark matter, and thus could
produce a measurable signal. I will focus on the detectability of this
emission from the Large Magellanic Cloud using current and upcoming
instruments, including GLASTand next generation Atmospheric Cherenkov
Telescopes.
|
|
Charles Hailey
Columbia University
Indirect Dark Matter
Search with Antideuterons : Progress and Future Prospects of GAPS
I discuss the experimental prospects for an indirect dark matter
search exploiting antideuterons.
Antideuterons are produced in neutralino- neutralino annihilations. The
predicted antideuteron flux in
many SUSY models is large enough to be detected with a sufficiently
sensitive instrument in either a
long duration balloon experiment or a satellite experiment. For modest
sensitivity experiments the
confusion of the primary antideuteron signature with secondary and
tertiary antideuterons is expected
to be negligible at low energies. The General Antiparticle Spectrometer
(GAPS)detects antideuterons
through the atomic deexcitation X-rays and pion annihilation star
produced when antideuterons are
slowed down and captured in a target. The near simultaneous X-rays of
precisely known energy and
the pion star form a very constraining signature of antideuterons,
permitting high background rejection
efficiencies. Analysis of the performance of a prototype GAPS tested in
an antiproton beam at the KEK
accelerator in Japan in spring 2004 will be presented. An upgraded
experiment performed in June 2005
at KEK will also be described. Plans for flight testing of this
prototype, as well as the timeline for an
actual balloon dark matter search, will also be described.
|
Speaker
Institution
Title
Abstract |
Francis Halzen
University of Wisconsin, Madison
The Highest Energy
Particles: Cosmic Rays, Gamma Rays and Neutrinos
Kilometer-scale neutrino detectors are discovery instruments covering
nuclear and particle physics, cosmology and astronomy. Examples of
their multidisciplinary missions include the search for the particle
nature of dark matter and for additional small dimensions of space. The
conceptual design of neutrino telescopes is very much anchored to the
observational fact that Nature accelerates protons to energies in
excess of 108 TeV; we do not how and we do not know where. We have
observed cosmic photons and neutrinos with energies of tens and
hundreds of TeV, respectively. We will discuss how connections to the
observed cosmic rays and TeV gamma rays set the scale of cosmic
neutrino fluxes and how neutrino telescopes may, in the end, also
contribute to the resolution of the cosmic ray puzzle(s).
|
Speaker
Institution
Title
Abstract |
Albrecht Karle
University of
Wisconsin, Madison
Status of IceCube and
Results from AMANDA II
The construction of the IceCube Neutrino Observatory at the South Pole
began in January 200
the deployment of 1 string and several surface detectors. More than 10
IceCube strings are plan
be deployed in January 2005. I will show data from the first IceCube
string and coincidences wi
surface air shower array. The performance and science potential of
IceCube will be discussed.
I will also present the current results from the AMANDA-II array, which
has been in operation sin
year 2000. Four years of data have been analyzed for high energy
neutrino emission from d
astrophysical sources, point sources, GRB, WIMPs and galactic sources
at TeV energies.
|
Speaker
Institution
Title
Abstract |
Stelios Kazantzidis
University of Chicago
Density Profiles of Cold Dark
Matter Substructure
TBD
|
|
John Kildea
McGill University
The Solar Tower
Atmospheric Cherenkov Effect Experiment
The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a
ground-based atmospheric Cherenkov telescope for the detection of very
high energy gamma rays from Galactic and extra-galactic sources. By
utilizing the large collection area provided by the solar mirrors of
the National Solar Thermal Test Facility in Albuquerque, New Mexico,
STACEE achieves a low energy threshold, around 150 GeV, for the
detection of gamma rays. We briefly describe the STACEE detector and
detail recent observations and results.
|
Speaker
Institution
Title
Abstract |
Martin Lemoine
Institut d'Astrophysique de Paris
Extra-galactic magnetic
fields and high energy cosmic rays
This contribution will argue that extra-Galactic magnetic fields of
moderate strength may provide a natural
explanation for the transition from Galactic to extra-Galactic cosmic
rays at the second knee (E~10**17 eV)
of the CR spectrum. Cosmic rays with energy lower than 10**17 eV cannot
reach the detector because the travel time from the source is longer
than the age of the Universe. A smooth fit to the all-particle CR
spectrum at all energies will be presented. The spectral index s~2.6
required to fit the ultra-high energy spectrum will be shown to emerge
naturally from Fermi acceleration at relativistic shocks.
|
|
John Matthews
U. of Utah
Search for Cross
Correlations of Ultra-High Energy Cosmic Rays with BL Lac Objects
The High-Resolution Fly's Eye Experiment (HiRes) is a stereo air
fluorescence detector for the study of cosmic rays with energies above
5*10^17 eV. Arrival directions of cosmic rays observed in stereo can be
resolved with a typical uncertainty of 0.5 degrees, making the
experiment ideal for small scale anisotropy studies. Here we present
the results of searches for correlation with astronomical sources, and
in particular the recently observed correlations with objects of the BL
Lac subclass of active galaxies.
|
Speaker
Institution
Title
Abstract |
Bob McElrath
University of California, Davis
Light
Dark Matter and Invisible Quarkonium Decays
If dark matter happens to be light and couples to the Standard
Model via some mediating boson, it may be discovered in existing
experiments at B-factories and low-energy colliders. We discuss
several
measurements including invisible decays of quarkonia, B-meson decays,
and radiative Upsilon and J/Psi decays which are sensitive to light dark
matter.
|
Speaker
Institution
Title
Abstract |
David Merritt
Rochester Institute of Technology
Dynamics of Dark
Matter at Galaxy Centers
The centers of galaxies are among the most promising
targets for indirect detection studies. However the prospects for
detection depend critically on the dark matter distribution on
sub-parsec scales. At these small radii, the gravitational
potential is dominated by stars and by the supermassive black hole, and
the dark matter distribution is not strongly
constrained either by kinematical data or by N-body studies.
Hence, the only way to constrain the dark matter density is via
theoretical studies of the time-dependent equations that describe its
evolution. I review the dominant interaction mechanisms and
discuss how they can be used to rule out extreme models for the dark
matter distribution, thus increasing the information that can be
gleaned from indirect detection searches.
|
Speaker
Institution
Title
Abstract |
Peter Meszaros
Pennsylvania State University
TeV Photons and Neutrinos from
GRB, SN and AGN
TeV photons and/or neutrinos associated with cosmic rays are
expected
in current models of GRB and AGNs, as well as possibly in
core-collapse
supernovae. Possible mechanisms and scenarios as well as detection
prospects are discussed.
|
Speaker
Institution
Title
Abstract |
Teresa Montaruli
University of Wisconsin, Madison
The ANTARES Neutrino Telescope
ANTARES is a project for the construction of a high energy
neutrino telescope in the Mediterranean
sea at a depth of 2.5 km, 40 km offshore La Seyne sur Mer
(Toulon, France). ANTARES main
scientific aims are the detection of neutrinos produced by cosmic
accelerators, such as gamma-ray
bursters, active galactic nuclei and pulsars embedded in
supernova remnants, and the detection of
dark matter particles. Twelve lines anchored at sea bed, spaced
by about 70 m, will hold 75 optical
modules each, which will contain photomultipliers for Cherenkov
light detection. The results of two test
lines, that have been recently deployed, will be presented. The
first of the final detector lines will be
deployed and connected to the electro-optical cable to shore by
the end of 2005. The status of the
project and the expected performance are going to be described.
|
Speaker
Institution
Title
Abstract |
Aravind Natarajan
University of Florida
Caustics in galactic
halos
The continuous infall of dark matter with low velocity dispersion
in galactic halos leads to the formation
of high density structures called caustics. Caustics are made up
of sections of the elementary
catastrophes and are stable to perturbations. The kind of
catastrophe involved and hence the caustic
structure, depends on the dark matter angular momentum
distribution. Since the dark matter
distribution at any point may be thought of as a superposition of
discrete flows, we may study caustics
by simulating a single cold flow falling in the potential caused
by the rest of the halo. The caustic is
obtained by plotting the points of infinite density. In real
halos, the density at the caustic is finite, but
very large. The results of the simulations are shown.
Implications for dark matter detection are
discussed.
|
Speaker
Institution
Title
Abstract |
Kaixuan Ni
Columbia University
Current status and prospects for
the XENON dark matter search experiment
Dark matter direct detection experiments play an important role
in unveiling the nature of dark matter.
The current direct detection experiments focus on the detection
of weakly interacting massive particles
(WIMPs) via their elastic scattering off the target nuclei. The
key challenge of these experiments is to
discriminate between nuclear recoils (from WIMPs) and electron
recoils (from background gamma
rays). The distinct ratio between ionization and scintillation
from a WIMP or gamma ray event in liquid
xenon makes it perfect for dark matter direct detection. A liquid
xenon detector is also much easier to
be scaled up in mass than others using different target
materials. We will present the major technical
accomplishments up to date in the R&D phase of the XENON
project. The background discrimination
potential, based on a small prototype, will be shown. A 3 kg
detector with 3D position sensitivity is
currently being tested. The 3D sensitivity allows further
rejection of background events that mimic the
nuclear recoil events from WIMPs. We will present the design and
prospects for a 10 kg detector
(XENON10), which will be deployed underground (Gran Sasso
National Lab, Italy) and start to take
physics data early next year.
|
Speaker
Institution
Title
Abstract |
Nikhil Padmanabhan
Princeton University
Detecting dark matter
annihilation with CMB polarization : Signatures and Experimental
Prospects
Dark matter (DM) annihilation during hydrogen recombination (z ~
1000) will alter the recombination
history of the Universe, and affect the observed CMB temperature
and polarization fluctuations. Unlike
other astrophysical probes of DM, this is free of the significant
uncertainties in modelling galactic
physics, and provides a method to detect and constrain the
cosmological abundances of these
particles. We parametrize the effect of DM annihilation as an
injection of ionizing energy at a rate
e_{dm}, and argue that this simple "on the spot'' modification is
a good approximation to the
complicated interaction of the annihilation products with the
photon-electron plasma. Generic models of
DM do not change the redshift of recombination, but change the
residual ionization after recombination.
This broadens the surface of last scattering, suppressing the
temperature fluctuations and enhancing
the polarization fluctuations. We use the temperature and
polarization angular power spectra to
measure these deviations from the standard recombination history,
and therefore, indirectly probe DM
annihilation.
|
Speaker
Institution
Title
Abstract |
Vasiliki Pavlidou
University of Illinois at Urbana-Champaign
Analytical Modeling of Cosmic
Accretion Shocks: The Role Of Environment
Cosmic shocks have attracted much interest as an acceleration
site of relativistic particles and
consequently as likely gamma-ray emitters. In fact, several
individual objects hosting cosmic shocks
are expected to be identifiable as gamma-ray sources by GLAST. In
this talk, we discuss
analytic models for the population of cosmic accretion shocks.
Cosmic accretion shocks are formed at the interface between a
collapsed cosmic structure and its
surrounding diffuse intergalactic gas. The properties of each
shock depend on the properties of the
accretor as well as the physical conditions in its immediate
environment. Using the Double Distribution
of dark mater halos, which describes the statistical properties
of both the accretors and their
environment, we have constructed an analytical model for the
population of accretion shocks. We use
this model to examine how environmental factors affect the
statistical properties of cosmic accretion
shocks, as well as to evaluate the impact of such shocks on the
intergalactic medium and their
potential as gamma-ray emitters.
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Speaker
Institution
Title
Abstract |
Lidia Pieri
Stockholm University
Annihilation of Dark Matter in
Clumpy Halos
Recent numerical experiments have shown that a large fraction of
the dark mass in our Galactic halo is
not smoothly distributed but is condensed in virialized dark
substuctures as light as 10^-6 M_sun. In
this work we estimate the gamma-rays flux expected from dark
matter annihiliation occurring within
these minihalos, under the hypothesis that the bulk of dark
matter is composed by neutralinos. We
generated mock sky maps showing the angular distribution of the
expected gamma-ray signal and
assess its detectability with satellite-borne experiments such as
GLAST.
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Speaker
Institution
Title
Abstract |
Tijana Prodanovic
University of Illinois at Urbana-Champaign
Diffuse Gamma Rays: A Model
Independent Constraint
We present a model-independent approach of constraining both
Galactic and extragalactic diffuse
hadronic gamma-rays. Our method is based on the fact that no
clear signature of pions is present in
the diffuse gamma-ray spectrum. Our results bring us to the
alarming conclusion that a large fraction of
Galactic gamma-rays are still a mystery. Connecting lithium with
hadronic gamma-rays provides us
with another model-independent approach which we use to constrain
the "pionic" component of EGRB.
We also show how lithium can be used as a powerful probe of
cosmic-ray sources even at TeV
energies. Implications for GLAST will be discussed.
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Speaker
Institution
Title
Abstract |
Stefano Profumo
Florida State University
How heavy can neutralinos be? Implications for TeV
gamma rays
We study the phenomenology of neutralino dark matter within generic
supersymmetric scenarios where
the Gaugino and Higgsino masses are much lighter than the scalar soft
breaking masses (Split
Supersymmetry). We consider a low-energy model-independent approach and
show that the guidelines
in the definition of this general framework come from cosmology, which
forces the lightest neutralino to
have a mass smaller than 2.2 TeV. The testability of the framework is
addressed by discussing all
viable dark matter detection techniques. Current data on cosmic rays
antimatter, gamma-rays and on
the abundance of primordial 6Li already set significant constraints on
the parameter space.
Complementarity among future direct detection experiments, indirect
searches for antimatter and with
neutrino telescopes, and tests of the theory at future accelerators,
such as the LHC and a NLC, is
highlighted. Finally, we show how the analysis applies to a well-known
instance of a Split-SUSY
scenario, the focus point region of minimal supergravity.
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Speaker
Institution
Title
Abstract |
David Seckel
Bartol Research Institute, University of Delaware
Updated limits to the UHE
neutrino flux from the RICE experiment
RICE (Radio Ice Cherenkov Experiment) is designed to detect radio
pulses from showers induced by interactions of UHE neutrinos in
Antarctic ice. We present limits based on operation from 2000-2004.
These limits reflect an expanded data set as well as updated simulation
and analysis. Development efforts towards an improved and expanded
South Pole radio array will be discussed.
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Speaker
Institution
Title
Abstract |
Alan Sill
Texas Tech University
Cross Section Issues in Cosmic
Ray Physics
Interpretation and simulation of high energy cosmic ray showers
depends on models for the total and
inelastic cross sections at energies well above those at which
measurements are available. In this talk,
I review limitations on current laboratory measurements and give
a comparative survey of presently
available models with an eye toward determining where these might
be improved, and understanding
the range of current
understanding. This
talk can serve as a starting point for developing an
experimental and computational program for improving current
models.
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Speaker
Institution
Title
Abstract |
Andrew Sonnenschein
Fermi National Accelerator Laboratory
COUPP: A Bubble Chamber Search
for Dark Matter at Fermilab
Bubble chambers are promising devices for the direct detection of
WIMP dark matter. When operating
with low-vapor-pressure liquids, they can be made nearly
continuously sensitive to small nuclear recoils
from WIMP interactions, while remaining insensitive to the most
troublesome sources of environmental
background radiation. We have built a small (1 liter) chamber to
test this new approach and are now
operating it in the NuMI tunnel at Fermilab. If this test is
successful, it seems possible to build detectors
with 1 ton or more of sensitive mass, which could explore a large
fraction of the supersymmetric
parameter space for WIMPs.
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Speaker
Institution
Title
Abstract |
Todor Stanev
Bartol Research Institute, University of Delaware
High Energy Neutrinos and Cosmic
Rays
We discuss the connection between the production of high energy
astrophysical neutrinos and the
spectrum of the extragalactic cosmic rays.
Cosmogenic
neutrinos are produced in cosmic rays
photoproduction interactions on the microwave background and
other photon fields. In the case of
steeper cosmic ray acceleration spectra the infrared background
becomes important.
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Speaker
Institution
Title
Abstract |
Floyd Stecker
NASA Goddard Space Flight Center
The gamma ray opacity of
the Universe and high energy Astropysics tests of Lorentz invariance
violation
Observations of the multi-TeV spectra of the Mkn 501 and other nearby
BL Lac objects exhibit the high energy cutoffs predicted to be the
result of intergalactic annihilation interactions, primarily with IR
photons having a flux level as determined by various astronomical
observations. I will first report on detailed new calculations of the
opacity of the universe to high energy gamma rays produced by such
sources as a function of redshift based on new determinations of the
intergalactic IR-UV photon spectra at redshifts from 0 to 5. After
correcting for such intergalactic absorption, the spectra of Mkn 501
and Mkn 421 can be explained within the framework of synchrotron
self-Compton emission models. Stecker and Glashow have shown that the
existence of this annihilation via electron-positron pair production
puts strong constraints on Lorentz invariance violation. Such
constraints have important implications for some quantum gravity and
large extra dimensions models. I will also discuss calculations showing
that a much smaller amount of Lorentz invariance violation has
potential implications for understanding the spectra of ultrahigh
energy cosmic rays.
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Speaker
Institution
Title
Abstract |
Ray Stefanski
Fermi National Accelerator Laboratory
MiniBooNE
The theory of leptogenisis would form a remarkable answer to
matter asymmetry in the universe, if
there were to be evidence for CP or CPT violation in neutrino
interactions. MiniBooNE expects to
complete a test of the LSND effect later this year. This result
will change our expectations for CP/CPT
violation. This talk will examine some of the possibilities.
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Speaker
Institution
Title
Abstract |
Simon Swordy
University of Chicago
The VERITAS gamma-ray telescope
array
VERITAS is an array of four 12m air Cerenkov telescopes being
built at Kitt Peak National Observatory
in Arizona. The first telescope has been operational at a
prototype site at Mount Hopkins since October
2004. The full array is expected be operational at the Kitt Peak
in 2006. The first stereo observations
are planned for Fall 2005. This talk will focus on the technical
performance demonstrated by the first
telescope and provide some initial results on observations of the
Crab Nebula and other objects.
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Speaker
Institution
Title
Abstract |
Tim Tait
Argonne
National Laboratory
Dark Matter
Candidates from Theories with Extra Dimensions
I will discuss extra dimensions and how they may be responsible for the
dark
non-relativistic content of the universe. The key challenge for
extra
dimensions to realize a dark matter candidate is to explain why it is
sufficently
stable as to still be present in the universe today. I will address three
theories which meet this challenge: universal extra dimensions,
variations of Randall-Sundrum, and theories with a light radion.
Estimates
of the relic density to identify cosmologically interesting parameter sets, and
observation phenomena for all three cases will be reviewed.
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Speaker
Institution
Title
Abstract |
Andrew Taylor
Oxford University
The Impact of Heavy Nuclei on
the Cosmogenic Neutrino Flux
As ultra-high energy cosmic ray protons propagate through the
universe, they undergo photo-meson
interactions with the cosmic microwave background, generating the
`cosmogenic' neutrino flux. If a
substantial fraction of the cosmic ray primaries are heavy nuclei
rather than protons, however, they
would preferentially lose energy through photo-disintegration, so
the corresponding neutrino flux may
be substantially depleted. We investigate this issue using a
Monte Carlo simulation of cosmic ray
propagation through interagalactic radiation fields and assess
the impact of the altered neutrino fluxes
on next generation neutrino telescopes.
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Speaker
Institution
Title
Abstract |
Gordon Thomson
Rutgers University
Results from the
HiRes Experiment
The High Resolution Fly's Eye (HiRes) experiment is a
fluorescence experiment studying ultrahigh
energy cosmic rays. The two HiRes detectors are deployed atop
desert mountains in west-central
Utah. We have new results on the spectrum, composition, and
anisotropy of ultrahigh energy cosmic
rays, and on the proton-air cross section, which will be
presented at the workshop.
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Speaker
Institution
Title
Abstract |
Diego F. Torres
Lawrence Livermore National Laborator
The high energy emission
from star forming regions
This talk presents a summary of the results of the theoretical
modelling of the high energy gamma-ray
emission from extreme star forming regions. It focuses mostly in the
extragalactic cases Arp 220, the
nearest ultra-luminous galaxy, and NGC 253, the nearest starburst.
Detailed multiwavelength models
are presented, and predictions for GLAST and the new Cerenkov
telescopes are given.
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Speaker
Institution
Title
Abstract |
Mani Tripathi
University of California, Davis
Dark Matter search via a Gamma
Ray Survey of Draco
CACTUS is a ground-based ACT at the Solar 2 facility located near
Barstow, California and operated
by UC, Davis. It uses an array of 160 large solar tracking
mirrors (heliostats) and a camera with 80
photomultiplier tubes to collect atmospheric Cherenkov radiation
produced by intermediate energy air
showers. CACTUS has incorporated novel techniques of time
projection imaging and triggering to
improve upon the first generation sampling arrays of its kind.
Draco is a dwarf spheroidal galaxy within
the Milky Way local group and is known to be rich in Dark Matter
content. Various theoretical models in
high energy physics, mainly Supersymmetry, include particles that
could be the basic constituent of
Dark Matter. Furthermore, these particles could annihilate with
each other and produce gamma rays.
An excess of gamma ray emissions from Draco, for example, would
lend support to such theories or
else, constraint the parameters embedded in these models.
We have mounted a campaign to survey the region around Draco
using CACTUS. Gamma-rays from
Dark Matter annihilations are expected to be in the low energy
(50-200 GeV) regime. In earlier
measurements of the gamma-ray emissions from the Crab nebula, we
have established that CACTUS
is sensitive in this energy range, thus making it well-suited for
this survey. We will describe our
detector, present an energy spectrum for gamma-rays from the Crab
and provide a status report on our
Draco campaign.
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Speaker
Institution
Title
Abstract |
Farhad Yusef-Zadeh
Northwetern University
Multi-Wavelength Observations of
Sgr A*
I will describe the highlights of the results of one
of the most successful observing campaign in 2004 to study Sgr A* at
the Galactic center. I will concentrate on the variability
results in different wavelengths followed by their correlation and
periodicity analysis at various wavelengths which includes soft
gamma-rays/X-rays to radio wavelengths. I will also discuss some of
diffuse high energy sources in the environment of the
Galactic center.
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Speaker
Institution
Title
Abstract |
Andrew Zentner
Kavli Institute for Cosmological Physics and Department of
Substructure in Cold Dark Matter
Halos
I will begin with a brief review of substructure in cold dark
matter halos. Included in this review, I will
discuss the status of the so-called "missing satellites problem,"
I will emphasize the statistical
properties of halo substructures, the correlations between
subhalo properties with the properties of
their host halos, and recent results on substructure lensing.
After reviewing the status of cold dark
matter halo substructure, I will continue by discussing the
possibility of detecting gamma rays from dark
matter annihilations in the high density regions in the centers
of subhalos that should be distributed
about the Milky Way halo. I will also discuss the possibility
that subhalos bear early-forming black
holes into the Milky Way halo which may themselves be sources of
gamma rays.\
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