118 research outputs found
Extending SkyLLH software for neutrino point source analyses with 10 years of IceCube public data
Searching for the sources of high-energy cosmic particles requires
sophisticated analysis techniques, frequently involving hypothesis tests with
unbinned log-likelihood (LLH) functions. SkyLLH is an open-source, Python-based
software tool to build these LLH functions and perform likelihood-ratio tests.
We present a new easy-to-use and modular extension of SkyLLH that allows the
user to perform neutrino point source searches in the entire sky using ten
years of IceCube public data. To guide the user, SkyLLH provides tutorials
showing how to analyze the experimental data and calculate useful statistical
quantities. Here we describe the details of the analysis workflow and
illustrate some of the possible methods to work with the IceCube public
dataset. Additionally, we show that SkyLLH can reproduce the results from a
previous IceCube publication that used the public data release. We obtain a
similar local significance for the neutrino emission from a list of candidate
sources within a maximum shift of 0.5. Finally, the measured neutrino
flux from the most significant source candidate, NGC 1068, shows substantial
agreement with the previously published result.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023).
See arXiv:2307.13047 for all IceCube contribution
Correlating high-energy IceCube neutrinos with 5BZCAT blazars and RFC sources
We investigate the possibility that blazars in the Roma-BZCAT Multifrequency
Catalogue of Blazars (5BZCAT) are sources of the high-energy astrophysical
neutrinos detected by the IceCube Neutrino Observatory, as recently suggested
by Buson et al. (2022a,b). Although we can reproduce their
result, which applies to 7 years of neutrino data in the Southern sky, we find
no significant correlation with 5BZCAT sources when extending the search to the
Northern sky, where IceCube is most sensitive to astrophysical signals. To
further test this scenario, we use a larger sample consisting of 10 years of
neutrino data recently released by the IceCube collaboration, this time finding
no significant correlation in either the Southern or the Northern sky. These
results suggest that the strong correlation reported by Buson et al. (2022a,b)
using 5BZCAT could be due to a statistical fluctuation and possibly the spatial
and flux non-uniformities in the blazar sample. We perform some additional
correlation tests using the more uniform, flux-limited, and blazar-dominated
Radio Fundamental Catalogue (RFC) and find a equivalent
p-value when correlating it with the 7-year Southern neutrino sky. However,
this correlation disappears completely when extending the analysis to the
Northern sky and when analyzing 10 years of all-sky neutrino data. Our findings
support a scenario where the contribution of the whole blazar class to the
IceCube signal is relevant but not dominant, in agreement with most previous
studies.Comment: Accepted for publication in ApJ
Extending the IceCube search for neutrino point sources in the Northern sky with additional years of data
The IceCube Neutrino Observatory is a one-cubic-kilometer-sized neutrino
telescope deployed deep in the Antarctic ice at the South Pole. One of
IceCube's major goals is finding the origins of astrophysical high-energy
neutrinos. In 2022, IceCube identified the strongest point-like neutrino source
so far, the active galaxy NGC 1068. Analyzing 9 years of muon-neutrino data
from the Northern Sky recorded between 2011 and 2020, the emission from NGC
1068 is significant at 4.2. We present a planned extension to this
search with additional years of data. One of these years includes data from
2010 when IceCube was only partially constructed. We discuss the improvement in
sensitivity and discovery potential for neutrino point sources across the
Northern sky. We show that by building on the established analysis techniques,
previous observations could be improved, not only for NGC 1068 but for all
possible sources in the Northern sky.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023).
See arXiv:2307.13047 for all IceCube contribution
Predicting respiratory failure in patients infected by SARS-CoV-2 by admission sex-specific biomarkers
Background: Several biomarkers have been identified to predict the outcome of COVID-19 severity, but few data are available regarding sex differences in their predictive role. Aim of this study was to identify sex-specific biomarkers of severity and progression of acute respiratory distress syndrome (ARDS) in COVID-19.
Methods: Plasma levels of sex hormones (testosterone and 17β-estradiol), sex-hormone dependent circulating molecules (ACE2 and Angiotensin1-7) and other known biomarkers for COVID-19 severity were measured in male and female COVID-19 patients at admission to hospital. The association of plasma biomarker levels with ARDS severity at admission and with the occurrence of respiratory deterioration during hospitalization was analysed in aggregated and sex disaggregated form.
Results: Our data show that some biomarkers could be predictive both for males and female patients and others only for one sex. Angiotensin1-7 plasma levels and neutrophil count predicted the outcome of ARDS only in females, whereas testosterone plasma levels and lymphocytes counts only in males.
Conclusions: Sex is a biological variable affecting the choice of the correct biomarker that might predict worsening of COVID-19 to severe respiratory failure. The definition of sex specific biomarkers can be useful to alert patients to be safely discharged versus those who need respiratory monitoring
Measuring the Neutrino Cross Section Using 8 years of Upgoing Muon Neutrinos Observed with IceCube
The IceCube Neutrino Observatory detects neutrinos at energies orders of magnitude higher than those available to current accelerators. Above 40 TeV, neutrinos traveling through the Earth will be absorbed as they interact via charged current interactions with nuclei, creating a deficit of Earth-crossing neutrinos detected at IceCube. The previous published results showed the cross section to be consistent with Standard Model predictions for 1 year of IceCube data. We present a new analysis that uses 8 years of IceCube data to fit the ν absorption in the Earth, with statistics an order of magnitude better than previous analyses, and with an improved treatment of systematic uncertainties. It will measure the cross section in three energy bins that span the range 1 TeV to 100 PeV. We will present Monte Carlo studies that demonstrate its sensitivity
Multi-messenger searches via IceCube’s high-energy neutrinos and gravitational-wave detections of LIGO/Virgo
We summarize initial results for high-energy neutrino counterpart searches coinciding with gravitational-wave events in LIGO/Virgo\u27s GWTC-2 catalog using IceCube\u27s neutrino triggers. We did not find any statistically significant high-energy neutrino counterpart and derived upper limits on the time-integrated neutrino emission on Earth as well as the isotropic equivalent energy emitted in high-energy neutrinos for each event
In-situ estimation of ice crystal properties at the South Pole using LED calibration data from the IceCube Neutrino Observatory
The IceCube Neutrino Observatory instruments about 1 km3 of deep, glacial ice at the geographic South Pole using 5160 photomultipliers to detect Cherenkov light emitted by charged relativistic particles. A unexpected light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow direction of the ice. Birefringent light propagation has been examined as a possible explanation for this effect. The predictions of a first-principles birefringence model developed for this purpose, in particular curved light trajectories resulting from asymmetric diffusion, provide a qualitatively good match to the main features of the data. This in turn allows us to deduce ice crystal properties. Since the wavelength of the detected light is short compared to the crystal size, these crystal properties do not only include the crystal orientation fabric, but also the average crystal size and shape, as a function of depth. By adding small empirical corrections to this first-principles model, a quantitatively accurate description of the optical properties of the IceCube glacial ice is obtained. In this paper, we present the experimental signature of ice optical anisotropy observed in IceCube LED calibration data, the theory and parametrization of the birefringence effect, the fitting procedures of these parameterizations to experimental data as well as the inferred crystal properties.</p
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