The Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is planned to be the next generation ground based observatory for very high energy (VHE) gamma-ray astronomy. Gamma-rays provide a powerful insight into the non-thermal universe and hopefully a unique probe for new physics. Imaging Cherenkov telescopes have already discovered more than 170 VHE gamma-ray emitters providing plentiful of valuable data and clearly demonstrating the power of this technique. In spite of the impressive results there are indications that the known sources represent only the tip of the iceberg. A major step in sensitivity is needed to increase the number of detected sources, observe short time-scale variability and improve morphological studies of extended sources. An extended energy coverage is advisable to observe far-away extragalactic objects and improve spectral analysis. CTA aims to increase the sensitivity by an order of magnitude compared to current facilities, to extend the accessible gamma-ray energies from a few tens of GeV to a hundred of TeV, and to improve on other parameters like angular and energy resolution. CTA will provide moreover a full sky-coverage by featuring an array of imaging atmospheric Cherenkov telescopes in both hemispheres. This paper presents an overview of the technical design and summarize the current status of the project. CTA prospects for some key science topics like the origin of relativistic cosmic particles, the acceleration mechanisms in extreme environments such as neutron stars and black holes and searches for Dark Matter are discussed

Expected performance of the ASTRI mini-array in the framework of the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) Observatory is a world-wide project for the ground-based study of the sources of the highest energy photons. By adopting telescopes of three different size categories it will cover the wide energy range from tens of GeV up to hundreds of TeV, limited only by the source physical properties and the gamma absorption by the extragalactic background light. The full sky coverage will be assured by two arrays, one in each hemisphere. An array of small size telescopes (SSTs), covering the highest energy region (3-100 TeV), the region most flux limited for current imaging atmospheric Cherenkov telescopes, is planned to be deployed at the southern CTA site in the first phase of the CTA project. The ASTRI collaboration has developed a prototype of a dual mirror SST equipped with a SiPM-based focal plane (ASTRI SST-2M) and has proposed to install a mini-array of nine of such telescopes at the CTA southern site (the ASTRI mini-array). In order to study the expected performance and the scientific capabilities of different telescope configurations, full Monte Carlo (MC) simulations of the shower development in the atmosphere for both gammas and hadronic background have been performed, followed by detailed simulations of the telescopes. In this work the expected performance of the ASTRI mini-array in terms of sensitivity, angular and energy resolution are presented and discussed

Science with the ASTRI mini-array for the Cherenkov Telescope Array: Blazars and fundamental physics

ASTRI ("Astronomia a Specchi con Tecnologia Replicante Italiana") is a flagship project of the Italian Ministry of Research (MIUR), devoted to the realization, operation and scientific validation of an end-to-end prototype for the Small Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array (CTA). The ASTRI SST-2M telescope prototype is characterized by a dual mirror, Schwarzschild-Couder optical design and a compact camera based on silicon photo-multipliers. It will be sensitive to multi-TeV very high energy (VHE) gamma rays up to 100 TeV, with a PSF ∼ 6′ and a wide (9.6°) unaberrated optical field of view. Right after validation of the design in single-dish observations at the Serra La Nave site (Sicily, Italy) during 2015, the ASTRI collaboration will be able to start deployment, at the final CTA southern site, of the ASTRI mini-array, proposed to constitute the very first CTA precursor. Counting 9 ASTRI SST-2M telescopes, the ASTRI mini-array will overtake current IACT systems in differential sensitivity above 5 TeV, thus allowing unprecedented observations of known and predicted bright TeV emitters in this band, including some extragalactic sources such as extreme high-peaked BL Lacs with hard spectra. We exploited the ASTRI scientific simulator ASTRIsim in order to understand the feasibility of observations tackling blazar and cosmic ray physics, including discrimination of hadronic and leptonic scenarios for the VHE emission from BL Lac relativistic jets and indirect measurements of the intergalactic magnetic field and of the extragalactic background light. We selected favorable targets, outlining observation modes, exposure times, multi-wavelength coverage needed and the results expected. Moreover, the perspectives for observation of effects due to the existence of axion-like particles or to Lorentz invariance violations have been investigated

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

Simulation of the ASTRI two-mirrors small-size telescope prototype for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is a world-wide project to build a new generation ground-based gamma-ray instrument operating in the energy range from some tens of GeV to above 100 TeV. To ensure full sky coverage CTA will consist of two arrays of Imaging Atmospheric Cherenkov Telescopes (IACTs), one in the southern hemisphere and another one in the northern hemisphere. CTA has just completed the design phase and it is entering in the pre-production one that includes the development of telescope precursor mini-arrays. ASTRI is an ongoing project, to develop and install at the southern CTA site one of such mini-arrays composed by nine dual-mirror small size telescopes equipped with an innovative camera based on silicon photomultiplier sensors. The end-to-end telescope prototype, named ASTRI SST-2M, has been recently inaugurated at the Serra La Nave observing station, on Mount Etna, Italy. ASTRI SST-2M expected performance has been carefully studied using a full Monte Carlo simulation of the shower development in the atmosphere and detector response. Simulated data have been analyzed using the traditional Hillas moment analysis to obtain the expected angular and energy resolution. Simulation results, together with the comparison with the available experimental measurements, are shown

ASTRI Mini-Array Data Model Document

This document provides an overview of the data products of the ASTRI MA System, and their conceptual (and logical) data models. The goals are: - list the data products produced by the MA system and the related data product categories; - show the relationship between the data products; - define a short identifier for the data product; - refer to data streams in architectural diagrams without ambiguity; - define interfaces and data models

ASTRI Mini-Array Top Level Software Architecture

This document provides a comprehensive architectural overview of the ASTRI Mini-Array Software system (a.k.a MA Software or MA Software System), which manages observing projects, observation handling, array control and monitoring, data acquisition, archiving, processing and simulations of the Cherenkov and Intensity Interferometry observations, including science tools for the scientific exploitation of the ASTRI MA data. This document, using a number of different views, depicts different aspects of the Mini-Array software and describes the significant architectural decisions