577,376 research outputs found
Intrigue and potential of space exploration
A brief history of astronomy is presented. A chronology of events in the space program is summarized. The possibilities of interplanetary exploration are postulated. The accomplishments of astronomy in pointing the way to manned spaceflight and improved understanding of the solar system are examined
Multi-photon signal in supersymmetry comprising non-pointing photon(s) at the LHC
We study a distinct supersymmetric signal of multi-photons in association
with jets and missing transverse energy. At least one of these photons has the
origin in displaced vertex, thus delayed and non-pointing. We consider a
supersymmetric scenario in which the gravitino is the lightest supersymmetric
particle (LSP) (with a mass ) and the lightest neutralino is the
next-to-lightest supersymmetric particle (NLSP). The NLSP decays dominantly
into a photon and a gravitino within the detector with a decay length ranging
from 50-100 cm. In addition, we assume that the
second lightest neutralino and the lightest neutralino are nearly degenerate
and this leads to a prompt radiative decay of the next-to-lightest neutralino
into a photon and a lightest neutralino with a large branching ratio. Such
degenerate neutralinos can be realised in various representations of the
, , and Grand Unified Theories (GUTs). The non-pointing
photons can be reconstructed at the electromagnetic calorimeter of the ATLAS
inner-detector, which have been designed with good timing and directional
resolution. We find that with a centre-of-mass energy at an
integrated luminosity of 100 one may see evidence of hundreds of
tri-photon events and a few four-photons events at the LHC, in addition to
several thousands di-photon events. We also predict the event rates even at the
early phase of LHC run.Comment: 10 pages; 6 figure
Simulator for Microlens Planet Surveys
We summarize the status of a computer simulator for microlens planet surveys.
The simulator generates synthetic light curves of microlensing events observed
with specified networks of telescopes over specified periods of time.
Particular attention is paid to models for sky brightness and seeing,
calibrated by fitting to data from the OGLE survey and RoboNet observations in
2011. Time intervals during which events are observable are identified by
accounting for positions of the Sun and the Moon, and other restrictions on
telescope pointing. Simulated observations are then generated for an algorithm
that adjusts target priorities in real time with the aim of maximizing planet
detection zone area summed over all the available events. The exoplanet
detection capability of observations was compared for several telescopes.Comment: Proc. IAU Symp. No. 293 "Formation, detection, and characterization
of extrasolar habitable planets", ed. by N. Haghighipour. 4 pages, in pres
Observation guidelines for a Total Ozone Mapping Spectrometer (TOMS) in geosynchronous orbit
The successful utilization of Total Ozone Mapping Spectrometer (TOMS) measurements in low Earth orbit for the analysis of rapidly changing events has led to the consideration of a TOMS in geosynchronous orbit. This orbit should allow for the selection of temporal and spatial resolutions that are specifically designed for these events, plus the flexibility of selecting different sized areas and pointing the sensor to focus on the most interesting events. Separate temporal and spatial resolution guidelines plus recommended areal coverage have been developed for tropical cyclones, jet streams, the interaction between strong convection and the environment, and the surveillance of volcanoes. It is also suggested that the most effective use of TOMS would be simultaneous flights with microwave and high spatial resolution infrared temperature profiles
Kepler-like Multi-Plexing for Mass Production of Microlens Parallaxes
We show that a wide-field Kepler-like satellite in Solar orbit could obtain
microlens parallaxes for several thousand events per year that are identified
from the ground, yielding masses and distances for several dozen planetary
events. This is roughly an order of magnitude larger than previously-considered
narrow-angle designs. Such a satellite would, in addition, roughly double the
number of planet detections (and mass/distance determinations). It would also
yield a trove of brown-dwarf binaries with masses, and distances and
(frequently) full orbits, enable new probes of the stellar mass function,
identify isolated black-hole candidates. We show that the actual Kepler
satellite, even with degraded pointing, can demonstrate these capabilities and
make substantial initial inroads into the science potential. We discuss several
"Deltas" to the Kepler satellite aimed at optimizing microlens parallax
capabilities. Most of these would reduce costs. The wide-angle approach
advocated here has only recently become superior to the old narrow-angle
approach, due to the much larger number of ground-based microlensing events now
being discovered.Comment: ApJ Letters, in press, 12 pages, 4 figure
GMSB SUSY models with non pointing photons signatures in ATLAS at the LHC
The reconstruction of non pointing photons is a key feature for studying
gauge mediated supersymmetry breaking (GMSB) models at the LHC. In this article
the angular resolution of the ATLAS electromagnetic calorimeter is
characterized from a detailed simulation of the detector. Resulting
performances are used to reconstruct GMSB events with a fast simulation
program, taking into account reconstruction effects. Finally, the sensitivity
to extract the sparticles masses and the lightest neutralino lifetime is
estimated.Comment: 4 pages, 3 figures, to appear in the proceedings of the XXXXth
Rencontres de Moriond: QCD and High Energy Hadronic Interactions, La Thuile,
Italy, March 12-19, 200
Probing decaying heavy dark matter with the 4-year IceCube HESE data
After the first four years of data taking, the IceCube neutrino telescope has
observed 54 high-energy starting events (HESE) with deposited energies between
20 TeV and 2 PeV. The background from atmospheric muons and neutrinos is
expected to be of about 20 events, all below 100 TeV, thus pointing towards the
astrophysical origin of about 8 events per year in that data set. However,
their precise origin remains unknown. Here, we perform a detailed analysis of
this event sample (considering simultaneously the energy, hemisphere and
topology of the events) by assuming two contributions for the signal events: an
isotropic power-law flux and a flux from decaying heavy dark matter. We fit the
mass and lifetime of the dark matter and the normalization and spectral index
of an isotropic power-law flux, for various decay channels of dark matter. We
find that a significant contribution from dark matter decay is always slightly
favored, either to explain the excess below 100 TeV, as in the case of decays
to quarks or, as in the case of neutrino channels, to explain the three
multi-PeV events. Also, we consider the possibility to interpret all the data
by dark matter decays only, considering various combinations of two decay
channels. We show that the decaying dark matter scenario provides a better fit
to HESE data than the isotropic power-law flux.Comment: v1: 44 pages, 12 figures; v2: Published version, no change
Probing decaying heavy dark matter with the 4-year IceCube HESE data
After the first four years of data taking, the IceCube neutrino telescope has
observed 54 high-energy starting events (HESE) with deposited energies between
20 TeV and 2 PeV. The background from atmospheric muons and neutrinos is
expected to be of about 20 events, all below 100 TeV, thus pointing towards the
astrophysical origin of about 8 events per year in that data set. However,
their precise origin remains unknown. Here, we perform a detailed analysis of
this event sample (considering simultaneously the energy, hemisphere and
topology of the events) by assuming two contributions for the signal events: an
isotropic power-law flux and a flux from decaying heavy dark matter. We fit the
mass and lifetime of the dark matter and the normalization and spectral index
of an isotropic power-law flux, for various decay channels of dark matter. We
find that a significant contribution from dark matter decay is always slightly
favored, either to explain the excess below 100 TeV, as in the case of decays
to quarks or, as in the case of neutrino channels, to explain the three
multi-PeV events. Also, we consider the possibility to interpret all the data
by dark matter decays only, considering various combinations of two decay
channels. We show that the decaying dark matter scenario provides a better fit
to HESE data than the isotropic power-law flux.Comment: v1: 44 pages, 12 figures; v2: Published version, no change
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