arXiv subjects

J. Schnabel

Publications and source records attributed to J. Schnabel.

8 recordsLinked to original sources

arXiv2023

The Very-high-energy Open Data Format: towards a shared, open data format in very-high-energy astronomy

In very-high-energy (VHE) gamma-ray astronomy, the community is converging towards the use of a common open data format, called "Data formats for Gamma-ray Astronomy", for the high-level data products. This format is in use for ground-based TeV observatories like H.E.S.S., MAGIC or HAWC, some of whom plan to openly release high-level data products. These efforts are parallel to the development and use of open analysis software such as the Gammapy package. This open initiative has shown that it is possible to define common standards even without governance. With the advent of open VHE observatories (e.g. CTAO, KM3NeT) and an increase in both multi-wavelength and multi-messenger studies, such standards should evolve to support all of VHE multi-messenger astrophysics. For these reasons, a new initiative has been created to specify formats of high-level data from very and ultra high energy gamma-ray facilities and from VHE neutrino detectors. It also aims to better respect the FAIR principles and the IVOA recommendations.This communication will present the Very-high-energy Open Data Format (VODF) project that has been established by eleven VHE astroparticle facilities. Its structure, its organisation and its goal will be presented. Anchored in Open Science, our goal is to solicit comments and future contributions from the VHE astrophysics community.

astro-ph.IM↗

arXiv2020

Best licensing practices

The principle that research output should be open has, in recent years, been in-creasingly applied to data and software. Licensing is a key aspect to openness. Navi-gating the landscape of open source licenses can lead to complex discussions.During ADASS XXIX in 2019 it became clear that several groupsworldwide areworking on formalising the licensing of software and other digital assets. In this article,we summarise a discussion we had at ADASS XXX on the application of licensesto astronomical scientific software, and summarise the questionnaire we distributed inpreparation. We conclude that this topic is considered relevant and interesting by manymembers of our community, and that it should be pursued further.

astro-ph.IM↗

arXiv2020

Bayesian Sampling Bias Correction: Training with the Right Loss Function

We derive a family of loss functions to train models in the presence of sampling bias. Examples are when the prevalence of a pathology differs from its sampling rate in the training dataset, or when a machine learning practioner rebalances their training dataset. Sampling bias causes large discrepancies between model performance in the lab and in more realistic settings. It is omnipresent in medical imaging applications, yet is often overlooked at training time or addressed on an ad-hoc basis. Our approach is based on Bayesian risk minimization. For arbitrary likelihood models we derive the associated bias corrected loss for training, exhibiting a direct connection to information gain. The approach integrates seamlessly in the current paradigm of (deep) learning using stochastic backpropagation and naturally with Bayesian models. We illustrate the methodology on case studies of lung nodule malignancy grading.

cs.LG↗

arXiv2017

Time-dependent search for neutrino emission from x-ray binaries with the ANTARES telescope

ANTARES is currently the largest neutrino telescope operating in the Northern Hemisphere, aiming at the detection of high-energy neutrinos from astrophysical sources. Neutrino telescopes constantly monitor at least one complete hemisphere of the sky, and are thus well-suited to detect neutrinos produced in transient astrophysical sources. A timedependent search has been applied to a list of 33 x-ray binaries undergoing high flaring activities in satellite data (RXTE/ASM, MAXI and Swift/BAT) and during hardness transition states in the 2008-2012 period. The background originating from interactions of charged cosmic rays in the Earth's atmosphere is drastically reduced by requiring a directional and temporal coincidence with astrophysical phenomena. The results of this search are presented together with comparisons between the neutrino flux upper limits and the neutrino flux predictions from astrophysical models. The neutrino flux upper limits resulting from this search limit the jet parameter predictions for some astrophysical models.

astro-ph.HE↗

arXiv2016

A search for Secluded Dark Matter in the Sun with the ANTARES neutrino telescope

A search for Secluded Dark Matter annihilation in the Sun using 2007-2012 data of the ANTARES neutrino telescope is presented. Three different cases are considered: a) detection of dimuons that result from the decay of the mediator, or neutrino detection from: b) mediator that decays into a dimuon and, in turn, into neutrinos, and c) mediator that decays directly into neutrinos. As no significant excess over background is observed, constraints are derived on the dark matter mass and the lifetime of the mediator.

hep-ex↗

arXiv2016

High-energy Neutrino follow-up search of Gravitational Wave Event GW150914 with ANTARES and IceCube

We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on Sept. 14th, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and ANTARES neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within 500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and ANTARES were three and zero, respectively. This is consistent with the expected atmospheric background, and none of the neutrino candidates were directionally coincident with GW150914. We use this non-detection to constrain neutrino emission from the gravitational-wave event.

astro-ph.HE↗

arXiv2016

Constraints on the neutrino emission from the Galactic Ridge with the ANTARES telescope

Compelling evidence for the existence of astrophysical neutrinos has been reported by the IceCube collaboration. Some features of the energy and declination distributions of IceCube events hint at a North/South asymmetry of the neutrino flux. This could be due to the presence of the bulk of our Galaxy in the Southern hemisphere. The ANTARES neutrino telescope, located in the Mediterranean Sea, has been taking data since 2007. It offers the best sensitivity to muon neutrinos produced by galactic cosmic ray interactions in this region of the sky. In this letter a search for an extended neutrino flux from the Galactic Ridge region is presented. Different models of neutrino production by cosmic ray propagation are tested. No excess of events is observed and upper limits for different neutrino flux spectral indices are set. This constrains the number of IceCube events possibly originating from the Galactic Ridge. A simple power-law extrapolation of the Fermi-LAT flux to associated IceCube High Energy Starting Events is excluded at 90% confidence level.

astro-ph.HE↗

arXiv2015

First combined search for neutrino point-sources in the Southern Hemisphere with the ANTARES and IceCube neutrino telescopes

We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors which differ in size and location forms a window in the Southern sky where the sensitivity to point sources improves by up to a factor of two compared to individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the Southern sky and from a pre-selected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for $E^{-2.5}$ and $E^{-2}$ power-law spectra with different energy cut-offs.

hep-ex↗