405 research outputs found
Turismo y crisis: el comportamiento del inmobiliario turístico en la montaña española durante la última década. Estudio de casos: la Val d’Aran y Sierra Nevada
En esta comunicación se analiza, como respuesta al enunciado del título, la evolución reciente del parque de viviendas que puede estar vinculado a una función turístico-residencial. Se pretende valorar, a partir de los resultados, el papel que desempeña esta función en el proceso de dinamización local y de renovación de la montaña española como escenario turístico y detectar, asimismo, otros posibles fundamentos de dicha renovación. Se analizan específicamente los datos de los censos de vivienda y las estadísticas de viviendas construidas en destinos significativos previamente seleccionados. El estudio se centra en los últimos quince años, y se realiza a escala municipal. La comarca y el municipio constituyen unidades espaciales operativas idóneas a efectos del tratamiento estadístico de la información obtenida
Neutrinos below 100 TeV from the southern sky employing refined veto techniques to IceCube data
Many Galactic sources of gamma rays, such as supernova remnants, are expected
to produce neutrinos with a typical energy cutoff well below 100 TeV. For the
IceCube Neutrino Observatory located at the South Pole, the southern sky,
containing the inner part of the Galactic plane and the Galactic Center, is a
particularly challenging region at these energies, because of the large
background of atmospheric muons. In this paper, we present recent advancements
in data selection strategies for track-like muon neutrino events with energies
below 100 TeV from the southern sky. The strategies utilize the outer detector
regions as veto and features of the signal pattern to reduce the background of
atmospheric muons to a level which, for the first time, allows IceCube
searching for point-like sources of neutrinos in the southern sky at energies
between 100 GeV and several TeV in the muon neutrino charged current channel.
No significant clustering of neutrinos above background expectation was
observed in four years of data recorded with the completed IceCube detector.
Upper limits on the neutrino flux for a number of spectral hypotheses are
reported for a list of astrophysical objects in the southern hemisphere.Comment: 19 pages, 17 figures, 2 table
Search for transient optical counterparts to high-energy IceCube neutrinos with Pan-STARRS1
In order to identify the sources of the observed diffuse high-energy neutrino
flux, it is crucial to discover their electromagnetic counterparts. IceCube
began releasing alerts for single high-energy ( TeV) neutrino
detections with sky localisation regions of order 1 deg radius in 2016. We used
Pan-STARRS1 to follow-up five of these alerts during 2016-2017 to search for
any optical transients that may be related to the neutrinos. Typically 10-20
faint ( mag) extragalactic transients are found within the
Pan-STARRS1 footprints and are generally consistent with being unrelated field
supernovae (SNe) and AGN. We looked for unusual properties of the detected
transients, such as temporal coincidence of explosion epoch with the IceCube
timestamp. We found only one transient that had properties worthy of a specific
follow-up. In the Pan-STARRS1 imaging for IceCube-160427A (probability to be of
astrophysical origin of 50 %), we found a SN PS16cgx, located at 10.0'
from the nominal IceCube direction. Spectroscopic observations of PS16cgx
showed that it was an H-poor SN at z = 0.2895. The spectra and light curve
resemble some high-energy Type Ic SNe, raising the possibility of a jet driven
SN with an explosion epoch temporally coincident with the neutrino detection.
However, distinguishing Type Ia and Type Ic SNe at this redshift is notoriously
difficult. Based on all available data we conclude that the transient is more
likely to be a Type Ia with relatively weak SiII absorption and a fairly normal
rest-frame r-band light curve. If, as predicted, there is no high-energy
neutrino emission from Type Ia SNe, then PS16cgx must be a random coincidence,
and unrelated to the IceCube-160427A. We find no other plausible optical
transient for any of the five IceCube events observed down to a 5
limiting magnitude of mag, between 1 day and 25 days after
detection.Comment: 20 pages, 6 figures, accepted to A&
Planeamiento territorial sostenible: un reto para el futuro de nuestras sociedades; criterios aplicados
In a large part of the 17 sustainable development objectives set as goals for humanity by the UN, sustainability can be glimpsed. As a result of the dominant socio-productive model, the only way to head towards more sustainable territories that allow achieving and maintaining the well-being of the world's population is to bear in mind the need to properly plan territorial development. This work reflects on this need and takes a step forward in the definition of the main criteria to achieve territorial sustainability at regional and local scales
Searching for High-energy Neutrino Emission from Galaxy Clusters with IceCube
Galaxy clusters have the potential to accelerate cosmic rays (CRs) to ultrahigh energies via accretion shocks or embedded CR acceleration sites. The CRs with energies below the Hillas condition will be confined within the cluster and eventually interact with the intracluster medium gas to produce secondary neutrinos and gamma rays. Using 9.5 yr of muon neutrino track events from the IceCube Neutrino Observatory, we report the results of a stacking analysis of 1094 galaxy clusters with masses ≳10 M⊙ and redshifts between 0.01 and ∼1 detected by the Planck mission via the Sunyaev–Zel’dovich effect. We find no evidence for significant neutrino emission and report upper limits on the cumulative unresolved neutrino flux from massive galaxy clusters after accounting for the completeness of the catalog up to a redshift of 2, assuming three different weighting scenarios for the stacking and three different power-law spectra. Weighting the sources according to mass and distance, we set upper limits at a 90% confidence level that constrain the flux of neutrinos from massive galaxy clusters (≳10 M⊙) to be no more than 4.6% of the diffuse IceCube observations at 100 TeV, assuming an unbroken E− power-law spectrum
Search for Astrophysical Neutrinos from 1FLE Blazars with IceCube
The majority of astrophysical neutrinos have undetermined origins. The IceCube Neutrino Observatory has observed astrophysical neutrinos but has not yet identified their sources. Blazars are promising source candidates, but previous searches for neutrino emission from populations of blazars detected in ≳GeV gamma rays have not observed any significant neutrino excess. Recent findings in multimessenger astronomy indicate that high-energy photons, coproduced with high-energy neutrinos, are likely to be absorbed and reemitted at lower energies. Thus, lower-energy photons may be better indicators of TeV–PeV neutrino production. This paper presents the first time-integrated stacking search for astrophysical neutrino emission from MeV-detected blazars in the first Fermi Large Area Telescope low energy (1FLE) catalog using ten years of IceCube muon–neutrino data. The results of this analysis are found to be consistent with a background-only hypothesis. Assuming an E neutrino spectrum and proportionality between the blazars MeV gamma-ray fluxes and TeV–PeV neutrino flux, the upper limit on the 1FLE blazar energy-scaled neutrino flux is determined to be 1.64 × 10^-12} TeV cm s at 90% confidence level. This upper limit is approximately 1% of IceCube\u27s diffuse muon–neutrino flux measurement
A search for time-dependent astrophysical neutrino emission with IceCube data from 2012 to 2017
High-energy neutrinos are unique messengers of the high-energy universe,
tracing the processes of cosmic-ray acceleration. This paper presents analyses
focusing on time-dependent neutrino point-source searches. A scan of the whole
sky, making no prior assumption about source candidates, is performed, looking
for a space and time clustering of high-energy neutrinos in data collected by
the IceCube Neutrino Observatory between 2012 and 2017. No statistically
significant evidence for a time-dependent neutrino signal is found with this
search during this period since all results are consistent with the background
expectation. Within this study period, the blazar 3C 279, showed strong
variability, inducing a very prominent gamma-ray flare observed in 2015 June.
This event motivated a dedicated study of the blazar, which consists of
searching for a time-dependent neutrino signal correlated with the gamma-ray
emission. No evidence for a time-dependent signal is found. Hence, an upper
limit on the neutrino fluence is derived, allowing us to constrain a hadronic
emission model
LeptonInjector and LeptonWeighter: A neutrino event generator and weighter for neutrino observatories
We present a high-energy neutrino event generator, called LeptonInjector,
alongside an event weighter, called LeptonWeighter. Both are designed for
large-volume Cherenkov neutrino telescopes such as IceCube. The neutrino event
generator allows for quick and flexible simulation of neutrino events within
and around the detector volume, and implements the leading Standard Model
neutrino interaction processes relevant for neutrino observatories:
neutrino-nucleon deep-inelastic scattering and neutrino-electron annihilation.
In this paper, we discuss the event generation algorithm, the weighting
algorithm, and the main functions of the publicly available code, with
examples.Comment: 28 pages, 10 figures, 3 table
Improved Characterization of the Astrophysical Muon–neutrino Flux with 9.5 Years of IceCube Data
We present a measurement of the high-energy astrophysical muon–neutrino flux with the IceCube Neutrino Observatory. The measurement uses a high-purity selection of 650k neutrino-induced muon tracks from the northern celestial hemisphere, corresponding to 9.5 yr of experimental data. With respect to previous publications, the measurement is improved by the increased size of the event sample and the extended model testing beyond simple power-law hypotheses. An updated treatment of systematic uncertainties and atmospheric background fluxes has been implemented based on recent models. The best-fit single power-law parameterization for the astrophysical energy spectrum results in a normalization of and a spectral index , constrained in the energy range from 15 TeV to 5 PeV. The model tests include a single power law with a spectral cutoff at high energies, a log-parabola model, several source-class-specific flux predictions from the literature, and a model-independent spectral unfolding. The data are consistent with a single power-law hypothesis, however, spectra with softening above one PeV are statistically more favorable at a two-sigma level
Searching for eV-scale sterile neutrinos with eight years of atmospheric neutrinos at the IceCube Neutrino Telescope
We report in detail on searches for eV-scale sterile neutrinos, in the context of a 3+1 model, using eight years of data from the IceCube Neutrino Telescope. By analyzing the reconstructed energies and zenith angles of 305,735 atmospheric νμ and ¯νμ events we construct confidence intervals in two analysis spaces: sin2(2θ) vs Δm2¦41 under the conservative assumption θ=0; and sin (2θ) vs sin (2θ) given sufficiently large Δm2¦41 that fast oscillation features are unresolvable. Detailed discussions of the event selection, systematic uncertainties, and fitting procedures are presented. No strong evidence for sterile neutrinos is found, and the best-fit likelihood is consistent with the no sterile neutrino hypothesis with a p value of 8% in the first analysis space and 19% in the second
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