131 research outputs found
Hi-GAL, theHerschelinfrared Galactic Plane Survey: photometric maps and compact source catalogues
Aims. We present the first public release of high-quality data products (DR1) from Hi-GAL, the Herschel infrared Galactic Plane Survey. Hi-GAL is the keystone of a suite of continuum Galactic plane surveys from the near-IR to the radio and covers five wavebands at 70, 160, 250, 350 and 500 µm, encompassing the peak of the spectral energy distribution of cold dust for 8 < T < 50 K. This first Hi-GAL data release covers the inner
Milky Way in the longitude range 68◦ > t > −70◦ in a |b| ≤ 1◦ latitude strip. ∼ ∼
∼ ∼
Methods. Photometric maps have been produced with the ROMAGAL pipeline, which optimally capitalizes on the excellent sensitivity and
stability of the bolometer arrays of the Herschel PACS and SPIRE photometric cameras. It delivers images of exquisite quality and dynamical range, absolutely calibrated with Planck and IRAS, and recovers extended emission at all wavelengths and all spatial scales, from the point-spread function to the size of an entire 2◦ × 2◦ “tile” that is the unit observing block of the survey. The compact source catalogues were generated with the CuTEx algorithm, which was specifically developed to optimise source detection and extraction in the extreme conditions of intense and spatially varying background that are found in the Galactic plane in the thermal infrared.
Results. Hi-GAL DR1 images are cirrus noise limited and reach the 1σ-rms predicted by the Herschel Time Estimators for parallel-mode obser- vations at 6011 s−1 scanning speed in relatively low cirrus emission regions. Hi-GAL DR1 images will be accessible through a dedicated web-based image cutout service. The DR1 Compact Source Catalogues are delivered as single-band photometric lists containing, in addition to source posi- tion, peak, and integrated flux and source sizes, a variety of parameters useful to assess the quality and reliability of the extracted sources. Caveats and hints to help in this assessment are provided. Flux completeness limits in all bands are determined from extensive synthetic source experiments and greatly depend on the specific line of sight along the Galactic plane because the background strongly varies as a function of Galactic longitude. Hi-GAL DR1 catalogues contain 123210, 308509, 280685, 160972, and 85460 compact sources in the five bands
Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants
The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at
energies around 3~PeV. Sources which are capable of accelerating hadrons to
such energies are called hadronic PeVatrons. However, hadronic PeVatrons have
not yet been firmly identified within the Galaxy. Several source classes,
including Galactic Supernova Remnants (SNRs), have been proposed as PeVatron
candidates. The potential to search for hadronic PeVatrons with the Cherenkov
Telescope Array (CTA) is assessed. The focus is on the usage of very high
energy -ray spectral signatures for the identification of PeVatrons.
Assuming that SNRs can accelerate CRs up to knee energies, the number of
Galactic SNRs which can be identified as PeVatrons with CTA is estimated within
a model for the evolution of SNRs. Additionally, the potential of a follow-up
observation strategy under moonlight conditions for PeVatron searches is
investigated. Statistical methods for the identification of PeVatrons are
introduced, and realistic Monte--Carlo simulations of the response of the CTA
observatory to the emission spectra from hadronic PeVatrons are performed.
Based on simulations of a simplified model for the evolution for SNRs, the
detection of a -ray signal from in average 9 Galactic PeVatron SNRs is
expected to result from the scan of the Galactic plane with CTA after 10 hours
of exposure. CTA is also shown to have excellent potential to confirm these
sources as PeVatrons in deep observations with hours of
exposure per source.Comment: 34 pages, 16 figures, Accepted for publication in Astroparticle
Physic
Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.
Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited
New CC0\pi\ GENIE Model Tune for MicroBooNE
A novel tune has been made for the MicroBooNE experiment. The fit uses 4 new
parameters within the GENIE v3.0.6 Monte Carlo program. Charged current
pionless data from the T2K experiment was used. New uncertainties were
obtained. These results will be used in future MicroBooNE analyses.Comment: 24 pages, 14 figure
First Measurement of Differential Charged Current Quasielasticlike νμ-Argon Scattering Cross Sections with the MicroBooNE Detector
We report on the first measurement of flux-integrated single differential cross sections for chargedcurrent
(CC) muon neutrino (νμ) scattering on argon with a muon and a proton in the final state, 40Ar
ðνμ; μpÞX. The measurement was carried out using the Booster Neutrino Beam at Fermi National
Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an
exposure of 4.59 × 1019 protons on target. Events are selected to enhance the contribution of CC
quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single
differential cross sections in final state muon and proton kinematics.We measure the integrated per-nucleus
CCQE-like cross section (i.e., for interactions leading to a muon, one proton, and no pions above detection
threshold) of ð4.93 0.76stat 1.29sysÞ × 10−38 cm2, in good agreement with theoretical calculations. The
single differential cross sections are also in overall good agreement with theoretical predictions, except at
very forward muon scattering angles that correspond to low-momentum-transfer events.United States Department of Energy (DOE)National Science Foundation (NSF)Swiss National Science Foundation (SNSF)Science and Technology Facilities Council (STFC), part of the United Kingdom Research and InnovationRoyal Society of LondonAlbert Einstein Center for Fundamental Physics, Bern, SwitzerlandAzrieli FoundationZuckerman STEM Leadership ProgramIsrael Science FoundationVisiting Scholars Award Program of the Universities Research AssociationDE-AC02-07CH1135
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