165 research outputs found
A Search for Cosmic-ray Proton Anisotropy with the Fermi Large Area Telescope
In eight years of operation, the Fermi Large Area Telescope (LAT) has
detected a large sample of cosmic-ray protons. The LAT's wide field of view and
full-sky coverage make it an excellent instrument for studying anisotropy in
the arrival directions of protons at all angular scales. These capabilities
enable the LAT to make a full-sky 2D measurement of cosmic-ray proton
anisotropy complementary to many recent TeV measurements, which are only
sensitive to the right ascension component of the anisotropy. Any detected
anisotropy probes the structure of the local interstellar magnetic field or
could indicate the presence of a nearby source. We present the first results
from the Fermi-LAT Collaboration on the full-sky angular power spectrum of
protons from approximately 100 GeV - 10 TeV.Comment: Presented at ICRC 2017 in Busan, Korea - PoS(ICRC2017)17
Measurement of acoustic properties of South Pole ice for neutrino astronomy
South Pole ice is predicted to be the best medium for acoustic neutrino
detection. Moreover, ice is the only medium in which all three dense-medium
detection methods (optical, radio, and acoustic) can be used to monitor the
same interaction volume. Events detected in coincidence between two methods
allow significant background rejection confidence, which is necessary to study
rare GZK neutrinos. In 2007 and 2008 the South Pole Acoustic Test Setup (SPATS)
was installed as a research and development project associated with the IceCube
experiment. The purpose of SPATS is to measure the acoustic ice properties at
the South Pole in order to determine the feasibility of a future large hybrid
array. The deployment and performance of SPATS are described, as are first
results and work in progress on the sound speed, background noise, and
attenuation.Comment: 8 pages, 6 figures, 1 table, uses elsart5p.cls, to appear in the
proceedings of the Acoustic and Radio EeV Neutrino detection Activities
(ARENA) 2008 conferenc
Search for Acoustic Signals from Ultra-High Energy Neutrinos in 1500 km^3 of Sea Water
An underwater acoustic sensor array spanning ~1500 km^3 is used to search for
cosmic-ray neutrinos of ultra-high energies (UHE, E > 10^18 eV). Approximately
328 million triggers accumulated over an integrated 130 days of data taking are
analysed. The sensitivity of the experiment is determined from a Monte Carlo
simulation of the array using recorded noise conditions and expected waveforms.
Two events are found to have properties compatible with showers in the energy
range 10^24 to 5x10^24 eV and 10^22 to 5x10^22 eV. Since the understanding of
impulsive backgrounds is limited, a flux upper limit is set providing the most
sensitive limit on UHE neutrinos using the acoustic technique.Comment: Submitted to PRD. 8 pages, 12 figure
IceCube search for neutrinos from novae
Despite being one of the longest known classes of astrophysical transients,
novae continue to present modern surprises. The Fermi-LAT discovered that many
if not all novae are GeV gamma ray sources, even though theoretical models had
not even considered them as a possible source class. More recently, MAGIC and
H.E.S.S. detected TeV gamma rays from a nova. Moreover, there is strong
evidence that the gamma rays are produced hadronically, and that the
long-studied optical emission by novae is also shock-powered. If this is true,
novae should emit a neutrino signal correlated with their gamma-ray and optical
signals. We present the first search for neutrinos from novae. Because the
neutrino energy spectrum is expected to match the gamma-ray spectrum, we use an
IceCube DeepCore event selection focused on GeV-TeV neutrinos. We present
results from two searches, one for neutrinos correlated with gamma-ray emission
and one for neutrinos correlated with optical emission. The event selection
presented here is promising for additional astrophysical transients including
gamma-ray bursts and gravitational wave sources.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023).
See arXiv:2307.13047 for all IceCube contribution
Exploring the Galactic neutrino flux origins using IceCube datasets
Astrophysical neutrinos detected by the IceCube observatory can be of
Galactic or extragalactic origin. The collective contribution of all the
detected neutrinos allows us to measure the total diffuse neutrino Galactic and
extragalactic signal. In this work, we describe a simulation package that makes
use of this diffuse Galactic contribution information to simulate a population
of Galactic sources distributed in a manner similar to our own galaxy. This is
then compared with the sensitivities reported by different IceCube data samples
to estimate the number of sources that IceCube can detect. We provide the
results of the simulation that allows us to make statements about the nature of
the sources contributing to the IceCube diffuse signal.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023).
See arXiv:2307.13047 for all IceCube contribution
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