Gammapy: A Python package for gamma-ray astronomy

In this article, we present Gammapy, an open-source Python package for the analysis of astronomical $\gamma$-ray data, and illustrate the functionalities of its first long-term-support release, version 1.0. Built on the modern Python scientific ecosystem, Gammapy provides a uniform platform for reducing and modeling data from different $\gamma$-ray instruments for many analysis scenarios. Gammapy complies with several well-established data conventions in high-energy astrophysics, providing serialized data products that are interoperable with other software packages. Starting from event lists and instrument response functions, Gammapy provides functionalities to reduce these data by binning them in energy and sky coordinates. Several techniques for background estimation are implemented in the package to handle the residual hadronic background affecting $\gamma$-ray instruments. After the data are binned, the flux and morphology of one or more $\gamma$-ray sources can be estimated using Poisson maximum likelihood fitting and assuming a variety of spectral, temporal, and spatial models. Estimation of flux points, likelihood profiles, and light curves is also supported. After describing the structure of the package, we show, using publicly available $\gamma$-ray data, the capabilities of Gammapy in multiple traditional and novel $\gamma$-ray analysis scenarios, such as spectral and spectro-morphological modeling and estimations of a spectral energy distribution and a light curve. Its flexibility and power are displayed in a final multi-instrument example, where datasets from different instruments, at different stages of data reduction, are simultaneously fitted with an astrophysical flux model.Comment: 26 pages, 16 figure

Searching for VHE gamma-ray emission associated with IceCube neutrino alerts using FACT, H.E.S.S., MAGIC, and VERITAS

The realtime follow-up of neutrino events is a promising approach to searchfor astrophysical neutrino sources. It has so far provided compelling evidencefor a neutrino point source: the flaring gamma-ray blazar TXS 0506+056 observedin coincidence with the high-energy neutrino IceCube-170922A detected byIceCube. The detection of very-high-energy gamma rays (VHE, $\mathrm{E} >100\,\mathrm{GeV}$) from this source helped establish the coincidence andconstrained the modeling of the blazar emission at the time of the IceCubeevent. The four major imaging atmospheric Cherenkov telescope arrays (IACTs) -FACT, H.E.S.S., MAGIC, and VERITAS - operate an active follow-up program oftarget-of-opportunity observations of neutrino alerts sent by IceCube. Thisprogram has two main components. One are the observations of known gamma-raysources around which a cluster of candidate neutrino events has been identifiedby IceCube (Gamma-ray Follow-Up, GFU). Second one is the follow-up of singlehigh-energy neutrino candidate events of potential astrophysical origin such asIceCube-170922A. GFU has been recently upgraded by IceCube in collaborationwith the IACT groups. We present here recent results from the IACT follow-upprograms of IceCube neutrino alerts and a description of the upgraded IceCubeGFU system.<br

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016

The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, E >100 GeV) -rays. VHE -ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE -ray intranight variability in this source. While a common variability timescale of 1.5 hr is found, there is a significant deviation near the end of the flare with a timescale of ∼ 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE -ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the -ray flare, even though the detailed flux evolution differs from the VHE lightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, E >100 MeV) -ray band only a moderate flux increase is observed with Fermi-LAT, while the HE -ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the -ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located ∼ 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE rays have been produced far down the jet where turbulent plasma crosses a standing shock.Accepted manuscrip

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P &lt; 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

The 2011 Cordón Caulle eruption triggered by slip on the Liquiñe-Ofqui fault system

International audienceDetermining the mechanisms that promote large silicic eruptions is one of the biggest challenges in volcanic hazard assessment. The 2011-2012 Cordón-Caulle eruption in Chile was one of the largest silicic eruptions of the 21st century and was characterized by a rapid change from explosive to effusive behavior. This eruption was preceded by inflation from 2007 to 2009, followed by two years of barely any ground deformation. Despite intensive monitoring by geodetic and seismological data, its trigger remains undetermined. Here, we benefit from SAR imagery over the Puyehue Cordón-Caulle Volcanic Complex acquired by ALOS-1, ENVISAT and SENTINEL-1 data, to analyze the temporal and spatial behavior of ground displacements before, during and after the eruption. First, we find that a similar prolate spheroidal source explains the ground deformation for the pre-eruptive and post-eruptive periods. Then, we use 3D numerical elasto-plastic models to assess the failure conditions resulting from the pre-eruptive magma injection. Our results show that such a magma injection was too small to trigger the eruption. Therefore we explore other eruption triggers. Analytical elastic inversion models show that the ground displacements observed during the explosive phase may have been produced by slip motion along a NNW-striking dextral-strike slip, double-branch fault of the north-trending Liquiñe-Ofqui Fault System (LOFS), or along a single southern branch fault of the LOFS and collapse of the caldera. When investigating the elasto-plastic deformation pattern resulting from dextral slip along this branch-fault system, we obtain a sub-vertical dilatational plastic zone that connects the reservoir wall to the surface in a location that coincides with that of the 2011 eruption. Hence, we propose that this LOFS branch-fault eventually destabilized (perhaps weakened by the 2007-2009 episode of magma injection), and then slipped in a way that opened channels for fluid migration from the magma reservoir up to the surface

Increased Incidence and Characteristics of Alveolar Echinococcosis in Patients With Immunosuppression-Associated Conditions.

International audienceBACKGROUND: An increased incidence of alveolar echinococcosis (AE) in patients with immunosuppression (IS) has been observed; our aim was to study this association and its characteristics. METHODS: Fifty AE cases with IS-associated conditions (ISCs) before or at AE diagnosis were collected from the French AE registry (1982-2012, 509 cases). There were 30 cancers, 9 malignant hematological disorders, 14 chronic inflammatory diseases, 5 transplants, and 1 case of AIDS; 9 patients had ≥2 ISCs. Characteristics of the 42 IS/AE cases and the 187 non-IS/AE cases diagnosed during the period 2002-2012 were statistically compared. RESULTS: There was a significant increase in IS/AE cases over time. Risk factors did not differ between IS/AE and non-IS/AE patients. However, AE was more frequently an incidental finding (78% vs 42%) and was diagnosed at earlier stages (41% vs 23%) in IS/AE than in non-IS/AE patients. Serology was more often negative (14% vs 1%) and treatment efficacy was better (51% regression after 1-year treatment vs 27%) in IS/AE patients. All IS/AE patients but 7 took IS drugs; 7 received biotherapeutic agents. When not concomitant, AE occurred in IS patients within a 48-month median time period. Atypical presentation and abscess-, hemangioma-, and metastasis-like images delayed AE diagnosis in 50% of IS/AE patients, resulting in inappropriate treatment. Liver images obtained for 15 patients 1-5 years before diagnosis showed no AE lesions. Albendazole efficacy was good, but 19 of 48 treated patients experienced side effects. CONCLUSIONS: Patients with immunosuppression are at increased risk for occurrence, delayed diagnosis, and progression of AE

Intraguild predation involving Harmonia axyridis: a review of current knowledge and future perspectives.

As an effective generalist predator of aphids and other hemipteran pests H. axyridis has been a successful biological control agent. However, the very functional traits that have contributed to its success in this regard also implicate it as an intraguild predator that poses a significant risk not only to the diversity of other natural enemies of Hemiptera (and their associated ecosystem services), but to biodiversity more widely. In this paper we will specifically review the existing data on intraguild predation involving H. axyridis, and consider the strength and symmetry of such interactions both within its native guild and within exotic guilds where it has established as an invasive alien. We will use these studies to interpret the observed population declines in predator diversity in the field, predict species at risk in regions not yet invaded and consider implications for resulting ecosystem services. We will also indicate gaps in our knowledge that require further study in order to identify opportunities for mitigation