1,402 research outputs found
In Search for Extraterrestrial High Energy Neutrinos
In this paper we review the search for astrophysical neutrinos. We begin by
summarizing the various theoretical predictions which correlate the expected
neutrino flux with data from other messengers, specifically gammas and
ultra-high energy cosmic rays. We then review the status and results of
neutrino telescopes in operation and decommissioned, the methods used for data
analysis and background discrimination. Particular attention is devoted to the
challenge enforced by the highly uncertain atmospheric muon and neutrino
backgrounds in relation to searches of diffuse neutrino fluxes. Next, we
examine the impact of existing limits on neutrino fluxes on studies of the
chemical composition of cosmic rays. After that, we show that not only do
neutrinos have the potential to discover astrophysical sources, but the huge
statistics of atmospheric muons can be a powerful tool as well. We end by
discussing the prospects for indirect detection of dark matter with neutrino
telescopes.Comment: Solicited Review Article submitted to Annual Review of Nuclear and
Particle Science; 50 pages and 15 figures; the review is limited to 150
references, so many of them have been grouped. See
http://www.icecube.wisc.edu/~tmontaruli/review for errata and other feature
Neutrino signal from extended Galactic sources in IceCube
We explore the detectability of the neutrino flux from the entire Galactic
Plane or from a part of it with IceCube. We calculate the normalization and the
spectral index of the neutrino power law spectrum from different regions of the
Galactic plane, based on the observed spectral characteristics of the pion
decay gamma-ray diffuse emission observed by the Fermi/LAT telescope in the
energy band above 100 GeV. We compare the neutrino flux calculated in this way
with the sensitivity of IceCube for the detection of extended sources. Assuming
a binned extended source analysis method, we find that the only possible
evidence for neutrino emission for sources located in the Northern hemisphere
is from the Cygnus region after 20 years of exposure. For other parts of the
Galactic Plane even a 20 years exposure with IceCube is not sufficient for the
detection. Taking into account marginal significance of the detectable source
in the Cygnus region, we find a precise position and size of the source region
which optimizes the signal-to-noise ratio for neutrinos. We also calculate the
low-energy threshold above which the neutrino signal could be detected with the
highest signal-to-noise ratio. This calculation of precise source position,
size and energy range, based on the gamma-ray data, could be used to remove the
'trial factor' in the analysis of the real neutrino data of IceCube. We notice
that the diffuse neutrino emission from the inner Galactic Plane in the
Southern Hemisphere is much brighter. A neutrino detector with characteristics
equivalent to IceCube, but placed at the Northern Hemisphere (such as KM3NeT),
would detect several isolated neutrino sources in the Galactic Plane within
just 5 years exposure at 5{\sigma} level. These isolated sources of ~TeV
neutrinos would unambiguously localize sources of cosmic rays which operated
over the last 10 thousand years in the Galaxy.[abridged]Comment: submitted to A&
An exploration of hadronic interactions in blazars using IceCube
Context: Hadronic models, involving matter (proton or nuclei) acceleration in
blazar jets, imply high energy photon and neutrino emissions due to
interactions of high-energy protons with matter and/or radiation in the source
environment. Aims: This paper shows that the sensitivity of the IceCube
neutrino telescope in its 40-string configuration (IC-40) is already at the
level of constraining the parameter space of purely hadronic scenarios of
activity of blazars. Methods: Assuming that the entire source power originates
from hadronic interactions, and assuming that the models describe the data, we
estimate the expected neutrino flux from blazars based on the observed
gamma-ray flux by Fermi, simultaneously with IC-40 observations. We consider
two cases separately to keep the number of constrainable parameters at an
acceptable level: proton-proton or proton-gamma interactions are dominant.
Comparing the IC-40 sensitivity to the neutrino flux expected from some of the
brightest blazars, we constrain model parameters characterizing the parent
high-energy proton spectrum. Results: We find that when pp interactions
dominate, some constraints on the primary proton spectrum can be imposed. For
instance, for the tightest constrained source 3C 454.3, the very high energy
part of the spectra of blazars is constrained to be harder than E^-2 with
cut-off energies in the range of Ecut >10^18 eV. When interactions of
high-energy protons on soft photon fields dominate, we can find similarly tight
constraints on the proton spectrum parameters. [abridged]Comment: accepted for publication in A&
High energy extension of the FLUKA atmospheric neutrino flux
The atmospheric neutrino flux calculated with FLUKA was originally limited to
100-200 GeV for statistical reasons. In order to make it available for the
analysis of high energy events, like upward through-going muons detected by
neutrino telescopes, we have extended the calculation so to provide a reliable
neutrino yield per primary nucleon up to about 10**6 GeV/nucleon, as far as the
interaction model is concerned. We point out that the primary flux model above
100 GeV/nucleon still contributes with an important systematic error to the
neutrino flux.Comment: Extended version (10 pages) of the contribution to ICRC 2003, with
the addition of flux table
Air Shower Measurements in the Primary Energy Range from PeV to EeV
Recent results of advanced experiments with sophisticated measurements of
cosmic rays in the energy range of the so called knee at a few PeV indicate a
distinct knee in the energy spectra of light primary cosmic rays and an
increasing dominance of heavy ones towards higher energies. This leads to the
expectation of knee-like features of the heavy primaries at around 100 PeV. To
investigate in detail this energy region several new experiments are or will be
devised.Comment: 4 pages; submitted to Proceedings of 2nd Workshop on TeV
Astrophysics, Aug 28-31, 2006, Madison, W
Comparison of the FLUKA calculations with CAPRICE94 data on muons in atmosphere
In order to benchmark the 3-dimensional calculation of the atmospheric neutrino flux based on the FLUKA Monte Carlo code, muon fluxes in the atmosphere have been computed and compared with data taken by the CAPRICE94 experiment at ground level and at different altitudes in the atmosphere. For this purpose only two additions have been introduced with respect to the neutrino flux calculation: the specific solar modulation corresponding to the period of data taking and the bending of charged particles in the atmosphere. Results are in good agreement with experimental data, although improvements in the model are possible. At this level, however, it is not possible to disentangle the interplay between the primary flux and the interaction model.In order to benchmark the 3-dimensional calculation of the atmospheric neutrino flux based on the FLUKA Monte Carlo code, muon fluxes in the atmosphere have been computed and compared with data taken by the CAPRICE94 experiment at ground level and at different altitudes in the atmosphere. For this purpose only two additions have been introduced with respect to the neutrino flux calculation: the specific solar modulation corresponding to the period of data taking and the bending of charged particles in the atmosphere. Results are in good agreement with experimental data, although improvements in the model are possible. At this level, however, it is not possible to disentangle the interplay between the primary flux and the interaction model.In order to benchmark the 3-dimensional calculation of the atmospheric neutrino flux based on the FLUKA Monte Carlo code, muon fluxes in the atmosphere have been computed and compared with data taken by the CAPRICE94 experiment at ground level and at different altitudes in the atmosphere. For this purpose only two additions have been introduced with respect to the neutrino flux calculation: the specific solar modulation corresponding to the period of data taking and the bending of charged particles in the atmosphere. Results are in good agreement with experimental data, although improvements in the model are possible. At this level, however, it is not possible to disentangle the interplay between the primary flux and the interaction model.In order to benchmark the 3-dimensional calculation of the atmospheric neutrino flux based on the FLUKA Monte Carlo code, muon fluxes in the atmosphere have been computed and compared with data taken by the CAPRICE94 experiment at ground level and at different altitudes in the atmosphere. For this purpose only two additions have been introduced with respect to the neutrino flux calculation: the specific solar modulation corresponding to the period of data taking and the bending of charged particles in the atmosphere. Results are in good agreement with experimental data, although improvements in the model are possible. At this level, however, it is not possible to disentangle the interplay between the primary flux and the interaction model.In order to benchmark the 3-dimensional calculation of the atmospheric neutrino flux based on the FLUKA Monte Carlo code, muon fluxes in the atmosphere have been computed and compared with data taken by the CAPRICE94 experiment at ground level and at different altitudes in the atmosphere. For this purpose only two additions have been introduced with respect to the neutrino flux calculation: the specific solar modulation corresponding to the period of data taking and the bending of charged particles in the atmosphere. Results are in good agreement with experimental data, although improvements in the model are possible. At this level, however, it is not possible to disentangle the interplay between the primary flux and the interaction model
Results from the Blazar Monitoring Campaign at the Whipple 10m Gamma-ray Telescope
In September 2005, the observing program of the Whipple 10 m gamma-ray
telescope was redefined to be dedicated almost exclusively to AGN monitoring.
Since then the five Northern Hemisphere blazars that had already been detected
at Whipple are monitored routinely each night that they are visible. Thanks to
the efforts of a large number of multiwavelength collaborators, the first year
of this program has been very successful. We report here on the analysis of
Markarian 421 observations taken from November, 2005 to May, 2006 in the
gamma-ray, X-ray, optical and radio bands.Comment: 4 pages; contribution to the 30th International Cosmic Ray
Conference, Merida, Mexico, July 200
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