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Abstract The Cherenkov Telescope Array and the KM3NeT neutrino telescopes are major upcoming facilities in the fields of $$\\gamma $$ γ -ray and neutrino astronomy, respectively. Possible simultaneous production of $$\\gamma $$ γ rays and neutrinos in astrophysical accelerators of cosmic-ray nuclei motivates a combination of their data. We assess the potential of a combined analysis of CTA and KM3NeT data to determine the contribution of hadronic emission processes in known Galactic $$\\gamma $$ γ -ray emitters, comparing this result to the cases of two separate analyses. In doing so, we demonstrate the capability of Gammapy, an open-source software package for the analysis of $$\\gamma $$ γ -ray data, to also process data from neutrino telescopes. For a selection of prototypical $$\\gamma $$ γ -ray sources within our Galaxy, we obtain models for primary proton and electron spectra in the hadronic and leptonic emission scenario, respectively, by fitting published $$\\gamma $$ γ -ray spectra. Using these models and instrument response functions for both detectors, we employ the Gammapy package to generate pseudo data sets, where we assume 200 h of CTA observations and 10 years of KM3NeT detector operation. We then apply a three-dimensional binned likelihood analysis to these data sets, separately for each instrument and jointly for both. We find that the largest benefit of the combined analysis lies in the possibility of a consistent modelling of the $$\\gamma $$ γ -ray and neutrino emission. Assuming a purely leptonic scenario as input, we obtain, for the most favourable source, an average expected 68% credible interval that constrains the contribution of hadronic processes to the observed $$\\gamma $$ γ -ray emission to below 15%.

The Cherenkov Telescope Array (CTA) is the major ground-based gamma-ray observatory planned for the next decade and beyond. Consisting of two large atmospheric Cherenkov telescope arrays (one in the southern hemisphere and one in the northern hemisphere), CTA will have superior angular resolution, a much wider energy range, and approximately an order of magnitude improvement in sensitivity, as compared to existing instruments. The CTA science programme will be rich and diverse, covering cosmic particle acceleration, the astrophysics of extreme environments, and physics frontiers beyond the Standard Model. This paper outlines the science goals for CTA and covers the current status of the project.

The Cherenkov Telescope Array (CTA) is the major ground-based gamma-ray observatory planned for the next decade and beyond. Consisting of two large atmospheric Cherenkov telescope arrays (one in the southern hemisphere and one in the northern hemisphere), CTA will have superior angular resolution, a much wider energy range, and approximately an order of magnitude improvement in sensitivity, as compared to existing instruments. The CTA science programme will be rich and diverse, covering cosmic particle acceleration, the astrophysics of extreme environments, and physics frontiers beyond the Standard Model. This paper outlines the science goals for CTA and covers the current status of the project.

The Cherenkov Telescope Array (CTA) will bring a whole new insight to the gamma-ray Universe. In order to fulfill its performance requirements, we need to understand and correct the atmospheric effects that influence the acquired instrument data. One such systematic effect is due to the varying molecular density profile with time. We have studied such profiles for both CTA sites using publicly available historical data assimilation archives. Our study reveals that we can distinguish at least three differentiated seasonal periods at the northern site and at least two at the southern site, that allow to model the molecular part of the atmosphere using average profiles, as done with current Cherenkov telescope projects. Seasonal transitions are smoother at the southern site than at the northern one. Moreover, the latter shows a greater amplitude in density variations at an altitude of 15 km. We also explored deviations of the molecular profiles with respect to their mean values using a 5-years data set and concluded that they are always found within specifications.

The future ground-based gamma-ray observatory, the Cherenkov Telescope Array (CTA) will require reliable monitoring of the atmosphere which is an inherent part of the detector. We discuss here the implementation of the extended method of the Cherenkov Transparency Coeffcient for the atmospheric calibration for the CTA. The method estimates the atmospheric transmission of Cherenkov light, relying on the measurement of the rates of cosmic ray-induced air showers that trigger different pairs of telescopes. We examine the performance of our approach utilizing Monte Carlo simulations assuming various atmospheric conditions and CTA observation configurations.

The Cherenkov Telescope Array (CTA) observatory will be deployed over two sites in the two hemispheres. Both sites will be equipped with four Large Size Telescopes (LSTs), which are crucial to achieve the science goals of CTA in the 20-200 GeV energy range. Each LST is equipped with a primary tessellated mirror dish of 23 m diameter, supported by a structure made mainly of carbon fibre reinforced plastic tubes and aluminum joints. This solution guarantees light weight (around 100 tons), essential for fast repositioning to any position in the sky in <20 seconds. The camera is composed of 1855 photomultiplier tubes and embeds the control, readout and trigger electronics. The detailed design is now complete and production of the first LST, which will serve as a prototype for the remaining seven, is ongoing. The installation of the first LST at the Roque de los Muchachos Observatory on the Canary island of La Palma (Spain) started in July 2016. In this paper we will outline the technical solutions adopted to fulfill the design requirements, present results of element prototyping and describe the installation and operation plans.

The Cherenkov Telescope Array (CTA) is the future instrument in ground-based gamma-ray astronomy in the energy range from 20 GeV to 300 TeV. Its sensitivity will surpass that of current generation experiments by a factor \\(\\sim\\)10, facilitated by telescopes of three sizes. The performance in the core energy regime will be dominated by Medium Size Telescopes (MST) with a reflector of 12 m diameter. A full-size mechanical prototype of the telescope structure has been constructed in Berlin. The performance of the prototype is being evaluated and optimisations, among others, facilitating the assembly procedure and mass production possibilities are being implemented. We present the current status of the developments from prototyping towards pre-production telescopes, which will be deployed at the final site.

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV to 10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

The Cherenkov Telescope Array (CTA) will be the future observatory for TeV gamma-ray astronomy. In order to increase the sensitivity and to extend the energy coverage beyond the capabilities of current facilities, its design concept features telescopes of three different size classes. Based on the experience from H.E.S.S. phase II, the Institute for Astronomy and Astrophysics T\"ubingen (IAAT) develops actuators for the mirror control system of the CTA Medium Size Telescopes (MSTs). The goals of this effort are durability, high precision, and mechanical stability under all environmental conditions. Up to now, several revisions were developed and the corresponding prototypes were extensively tested. In this contribution our latest design revision proposed for the CTA MSTs are presented.

Dwarf spheroidal galaxies are among the best environments that can be studied with Cherenkov telescopes for indirect searches of γ -ray signals coming from dark matter self-interaction (annihilation or decay), due to their proximity and negligible background emission. We present new determinations of the dark-matter amount – i.e. the astrophysical factors J and D – in dwarf-galaxy halos obtained through the MCMC Jeans analysis of their brightness and kinematic data. Such factors are of great importance to test the performances of the next-generation γ -ray instruments such as the Cherenkov Telescope Array in detecting dark-matter signals from astronomical environments, or constraining the limits to dark-matter physics parameters (particle mass and lifetime, annihilation cross section).