S. Lombardi

ASTRI data reduction software in the framework of the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is a worldwide project aimed at building the next-generation groundbased gamma-ray observatory. CTA will be composed of two arrays of telescopes of different sizes, one each in the Northern and Southern hemispheres, to achieve full-sky coverage and a ten-fold improvement in sensitivity with respect to the present-generation facilities. Within the CTA project, the Italian National Institute for Astrophysics (INAF) is developing an end-to-end prototype of one of the CTA Small-Size Telescope’s designs with a dual-mirror (SST-2M) Schwarzschild-Couder optics design. The prototype, named ASTRI SST-2M, is located at the INAF “M.C. Fracastoro” observing station in Serra La Nave (Mt. Etna, Sicily) and has started its verification and performance validation phase in fall 2017. A mini-array of (at least) nine ASTRI telescopes has been proposed to be deployed at the CTA southern site, during the pre-production phase, by means of a collaborative effort carried out by institutes from Italy, Brazil, and South Africa. The CTA ASTRI team has developed a complete end-to-end software package for the reduction, up to the final scientific products, of raw data acquired with ASTRI telescopes with the aim of actively contributing to the global ongoing activities for the official data handling system of the CTA observatory. The group is also undertaking a massive production of Monte Carlo simulation data using the same software chain adopted by the CTA Consortium. Both activities are also carried out in the framework of the European H2020-ASTERICS (Astronomy ESFRI and Research Infrastructure Cluster) project. In this work, we present the main components of the ASTRI data reduction software package and report the status of its development. Preliminary results on the validation of both data reduction and telescope simulation chains achieved with real data taken by the prototype and simulations are also discussed.

MAGIC detection of VHE Gamma-ray emission from NGC 1275 and IC 310

The MAGIC Cherenkov telescopes observed the Perseus cluste r sky region in stereo mode for nearly 90 hr from October 2009 to February 2011. This campaign led to the d iscovery of very high energy γ-ray emission from the central radio galaxy NGC 1275 and the head-tail radio galaxy IC 310. Here we report the results on the most recent discovery of NGC 1275 which was detected at low energies in th e 2010/2011 data. We also present latest results on IC 310, which had been detected in the 2009/2010 data.The MAGIC Cherenkov telescopes observed the Perseus cluster sky region in stereo mode for nearly 90 hr from October 2009 to February 2011. This campaign led to the discovery of very high energy Gamma-ray emission from the central radio galaxy NGC 1275 and the head-tail radio galaxy IC 310. Here we report the results on the most recent discovery of NGC 1275 which was detected at low energies in the 2010/2011 data. We also present latest results on IC 310, which had been detected in the 2009/2010 data.

Sensitivity for tau neutrinos at PeV energies and beyond with the MAGIC telescopes

The MAGIC telescopes, located at the Roque de los Muchachos Observatory (2200 a.s.l.) in the Canary Island of La Palma, are placed on the top of a mountain, from where a window of visibility of about 5 deg in zenith and 80 deg in azimuth is open in the direction of the surrounding ocean. This permits to search for a signature of particle showers induced by earth-skimming cosmic tau neutrinos in the PeV to EeV energy range arising from the ocean. We have studied the response of MAGIC to such events, employing Monte Carlo simulations of upward-going tau neutrino showers. The analysis of the shower images shows that air showers induced by tau neutrinos can be discriminated from the hadronic background coming from a similar direction. We have calculated the point source acceptance and the expected event rates, assuming an incoming tau neutrino flux consistent with IceCube measurements, and for a sample of generic neutrino fluxes from photo-hadronic interactions in AGNs. The analysis of about 30 hours of data taken toward the sea leads to a point source sensitivity for tau neutrinos at the level of the down-going point source analysis of the Pierre Auger Observatory.

Open high-level data formats and software for gamma-ray astronomy

In gamma-ray astronomy, a variety of data formats and proprietary software have been traditionally used, often developed for one specific mission or experiment. Especially for ground-based imaging atmospheric Cherenkov telescopes (IACTs), data and software are mostly private to the collaborations operating the telescopes. However, there is a general movement in science towards the use of open data and software. In addition, the next-generation IACT instrument, the Cherenkov Telescope Array (CTA), will be operated as an open observatory. nWe have created a Github organisation at this https URL where we are developing high-level data format specifications. A public mailing list was set up at this https URL and a first face-to-face meeting on the IACT high-level data model and formats took place in April 2016 in Meudon (France). This open multi-mission effort will help to accelerate the development of open data formats and open-source software for gamma-ray astronomy, leading to synergies in the development of analysis codes and eventually better scientific results (reproducible, multi-mission). nThis write-up presents this effort for the first time, explaining the motivation and context, the available resources and process we use, as well as the status and planned next steps for the data format specifications. We hope that it will stimulate feedback and future contributions from the gamma-ray astronomy community.

Search for tau neutrinos at PeV energies and beyond with the MAGIC telescopes

The MAGIC telescopes, located at the Roque de los Muchachos Observatory (2200 a.s.l.) in the Canary Island of La Palma, are placed on the top of a mountain, from where a window of visibility of about 5 deg in zenith and 80 deg in azimuth is open in the direction of the surrounding ocean. This permits to search for a signature of particle showers induced by earth-skimming cosmic tau neutrinos in the PeV to EeV energy range arising from the ocean. We have studied the response of MAGIC to such events, employing Monte Carlo simulations of upward-going tau neutrino showers. The analysis of the shower images shows that air showers induced by tau neutrinos can be discriminated from the hadronic background coming from a similar direction. We have calculated the point source acceptance and the expected event rates, for a sample of generic neutrino fluxes from photo-hadronic interactions in AGNs. The analysis of about 30 hours of data taken toward the sea leads to a point source sensitivity for tau neutrinos at the level of the down-going point source analysis of the Pierre Auger Observatory, if the AUGER observation time is dedicated to a similar amount by MAGIC.

MAGIC discovery and observation of the candidate extreme BL Lac object RBS 0723

The BL Lac object RBS 0723 belong to the category of “extreme” BL Lac object (EHBL). These sources are known to show an extreme frequency of their synch rotron and inverse Compton peaks in the spectral energy distribution (in the hard X-ray and TeV bands respectively). Furthermore, they are characterized by the extreme hardnes s of the UV-X-ray and (de-absorbed) TeV continua. These characteristics are explained in a lept onic synchrotron+SSC emission model under the assumption that the energy distribution of t he emitting relativistic electrons has a large value of the minimum Lorentz factor (10 5) and a rather low magnetic field intensity (10 −2

Short term and multi-band variability of the active nucleus of IC310

The MAGIC Telescopes detected the active galaxy IC 310 at very high energies (VHE, >100 GeV) during observations of the Perseus cluster in 2009 and 2010. This source had originally been classified as a head-tail radio galaxy. By contrast, recent high-resolution radio images obtained with the VLBA reveal the blazar-like structure of IC 310 on parsec scales. This object is also investigated in terms of its variability at X-ray and gamma-ray energies. Studies of the multi-band flux variability at different time periods are presented. The spectral evolution seems to be different in the VHE gamma-ray and X-ray bands.

Detection of very high energy gamma-ray emission from IC 310 by the MAGIC telescopes

We report on the detection of very high energy emission (> 300 GeV) from IC310 with the MAGIC telescopes. IC 310 is a head-tail radio galaxy located in the Perseus galaxy cluster, and has been recently detected by the Fermi-LAT instrument. The spectrum observed by the MAGIC telescopes is hard (spectral index −2.00± 0.14). Strong hints of variability are seen in the data. We discuss the possible origin of the very high energy gamma-ray emission.