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The Large-Sized Telescope (LST) prototype of the future Cherenkov Telescope Array (CTA) is located at the Northern site of CTA, on the Canary Island of La Palma. It is designed to provide optimal performance in the lowest part of the energy range covered by CTA, observing gamma rays down to energies of tens of GeV. The LST prototype started performing astronomical observations in November 2019 during the commissioning of the telescope and it has been taking data since then. In this contribution, we will present the tuning of the characteristics of the telescope in the Monte Carlo (MC) simulations to describe the data obtained, the estimation of its angular and energy resolution, and an evaluation of its sensitivity, both with simulations and with observations of the Crab Nebula.

Mrk 421 is a high-synchrotron-peaked blazar featuring bright and persistent GeV and TeV emission. We use the longest and densest ongoing unbiased observing campaign obtained at TeV and GeV energies during 5.5 years with the FACT telescope and the Fermi-LAT detector. The contemporaneous multi-wavelength observations were used to characterize the variability of the source and to constrain the underlying physical mechanisms. We study and correlate light curves obtained by nine different instruments from radio to gamma rays and found two significant results. The TeV and X-ray light curves are very well correlated with lag, if any, shorter than a day. The GeV light curve varies independently and accurately leads the variations observed at long wavelengths, in particular in the radio band. We find that the observations match the predictions of leptonic models and suggest that the physical conditions vary along the jet, when the emitting region moves outwards., PoS: Proceedings of Science, 354, ISSN:1824-8039, Proceedings of High Energy Phenomena in Relativistic Outflows VII PoS (HEPRO VII9)

Markarian 421 and Markarian 501 are Active Galactic Nuclei and two of the most prominent sources of very high energetic gamma rays. In contrast to the predominantly stable Crab Nebula, the two blazars have extremely variable gamma-ray fluxes. Those could be caused by erratic accretion flow instabilities, but also by processes leading to quasi periodic oscillations (QPOs). Recently, hints of such a QPO of Mrk 501 with a period of about 322 days have been observed with the Large Area Telescope on-board of the Fermi satellite at GeV energies featuring global and local significances of the signal above 99%. The First G-APD Cherenkov Telescope (FACT) has monitored a small sample of known TeV gamma-ray sources including Mrk 421 and Mrk 501 over the last seven years. Therefore, it is ideally suited for periodicity studies of Active Galactic Nuclei, as they require unbiased and continuous long-term observations. Based on measurements of the well-known gamma-ray flux originating from the Crab Nebula, corrections to the measured light curves are applied. In total, 2500~hours of data for each of the two blazars have been analysed using the Lomb-Scargle algorithm. The resulting periodogram of Mrk 501 shows a hint of QPO with a similar period as the one observed by Fermi/LAT., PoS: Proceedings of Science, 358, ISSN:1824-8039, Proceedings of 36th International Cosmic Ray Conference (ICRC 2019)

There exist many distributed storage systems that are mature and reliable. These systems are not fully adapted to the needs of an open astroparticle community mainly because they do not follow the Open Archival Information Systems (OAIS) standard. Moreover they require adaptations by each of the data centres at which they are installed. We introduce GAMAS, a novel distributed OAIS that tackles the problem of different technologies used at the various DCs. Instead of imposing the requirements of GAMAS to the DCs, we allows them to simply provide a python interface (or plugin) to their storage. This allows GAMAS to be easily deployed on top of different architecture and technologies, and to transparently allow users to retrieve data for processing, wherever they are. A metadata browsing system is incorporated within GAMAS and allows DCs as well as anonymous users to retrieve datasets based on high-level queries. GAMAS’ central database can be reconstructed from the archived data, which makes the system robust against corruption. We will expose the current status, architecture and functionalities of GAMAS and also detail the current test case which stores about 0.6 PB of data from the FACT experiment at separate data centres., PoS: Proceedings of Science, 358, ISSN:1824-8039, Proceedings of 36th International Cosmic Ray Conference (ICRC 2019)

The $\eta$ Carinae binary system hosts one of the most massive stars, which features the highest known mass-loss rate. This dense wind encounters the much faster wind expelled by the stellar companion, dissipating mechanical energy in the shock, where particles can be accelerated up to relativistic energies and subsequently produce very-high-energy $\gamma$-rays. We used data from the Fermi Large Area Telescope obtained during the first 7 years and spanning two passages of $\eta$ Carinae at periastron and compared them with the predictions of particle acceleration in hydrodynamic simulations. Two emission components can be distinguished. The low-energy component cuts off below 10 GeV and its flux, modulated by the orbital motion, varies by a factor less than 2. Short-term variability occurs at periastron. The flux of the high-energy component varies by a factor 3-4 but differently during the two periastrons. The variabilities observed at low energy, including some details of them, and these observed at high energy during the first half of the observations, match the prediction of the simulation, assuming a surface magnetic field in the range 0.4-1 kG. The high-energy component and the thermal X-ray emission were weaker than expected around the second periastron suggesting a modification of the wind density in the inner wind collision zone. Diffuse shock acceleration in the complex geometry of the wind collision zone of $\eta$ Carinae provides a convincing match to the observations and new diagnostic tools to probe the geometry and energetics of the system. Orbital modulations of the high-energy component can be distinguished from these of photo absorption by the four large size telescopes of the Cherenkov Telescope Array to be placed in the southern hemisphere. e-Astrogam could easily discriminate between the lepto-hadronic and the hadronic models for the gamma-ray emission and constrain acceleration physics in more extreme conditions than found in SNR.

FACT, the First G-APD Cherenkov Telescope, is an Imaging Air Cherenkov Telescope (IACT) operating since 2011 at the Observatorio del Roque de los Muchachos on the Canary Island of La Palma. As typical for IACTs, its reflector is comprised of smaller mirror facets and not protected by a dome. In the case of FACT, 30 hexagonal facets form a total mirror area of 9.5 m 2 . Hence, it is crucial to monitor the optical properties of this system and realign the facets if necessary. Up to now, measuring the Point Spread Function of FACT required human interaction to mount a screen and an optical camera. In this contribution, a new method to measure the optical Point Spread Function using directly the Cherenkov camera of the telescope is presented. Inspired by the method radio telescopes use to determine their resolution, the telescope is pointed towards a fixed position on the trajectory of a star. During the star’s passage through the field of view, the camera is read out using a fixed rate. In each event, the pedestal variance is determined for each pixel. This value is directly correlated with the amount of night sky background light a pixel received. Translating the time of the measurement to the position of the star in the camera enables to determine the optical point spread function from this measurement. As the measurement is done for each pixel along the trajectory of the star, the Point Spread Function can be determined not only for the camera center but for the entire field of view. In this contribution, the new method will also be compared with the existing methods of determining the optical Point Spread Function: direct measurement with an optical camera and the width of Muon ring events, PoS: Proceedings of Science, 301, ISSN:1824-8039

The SST-1M is a 4-m Davies-Cotton atmospheric Cherenkov telescope optimized to provide gamma-ray sensitivity above a few TeV. The SST-1M is proposed as part of the Small-Size Telescope array for the Cherenkov Telescope Array (CTA), the first prototype has already been deployed. The SST-1M control software of all subsystems (active mirror control, drive system, safety system, photo-detection plane, DigiCam, CCD cameras) and the whole telescope itself (master controller) uses the standard software design proposed for all CTA telescopes based on the ALMA Common Software (ACS) developed to control the Atacama Large Millimeter Array (ALMA). Each subsystem is represented by a separate ACS component, which handles the communication to and the operation of the subsystem. Interfacing with the actual hardware is performed via the OPC UA communication protocol, supported either natively by dedicated industrial standard servers (PLCs) or separate service applications developed to wrap lower level protocols (e.g. CAN bus, camera slow control) into OPC UA. Early operations of the telescope without the camera were already carried out. The camera is fully assembled and is capable to perform data acquisition using artificial light source.

The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads onboard China's Space Station, which is planned for operation starting around 2025 for about 10 ...

The $\eta$ Carinae binary system hosts one of the most massive stars, which features the highest known mass-loss rate. This dense wind encounters the much faster wind expelled by its stellar companion, dissipating mechanical energy in the shock, where particles can be accelerated up to relativistic energies and subsequently produce very-high-energy $\gamma$-rays. We used data from the Fermi Large Area Telescope obtained during the last 7 years and spanning two passages of $\eta$ Carinae at periastron and compared them with the predictions of particle acceleration in hydrodynamic simulations. Two emission components can be distinguished. The low-energy component cuts off below 10 GeV and its flux, modulated by the orbital motion, varies by a factor less than 2. Short-term variability occurs at periastron. The flux of the high energy component varies by a factor 3-4 but differently during the two periastrons. The variabilities observed at low-energy, including some details of them, and these observed at high-energy during the first half of the observations, do match the prediction of the simulation, assuming a surface magnetic field in the range 0.4-1 kG. The high-energy component and the thermal X-ray emission were weaker than expected around the second periastron suggesting a modification of the wind density in the inner wind collision zone. Diffuse shock acceleration in the complex geometry of the wind collision zone of η Carinae provides a convincing match to the observations and new diagnostic tools to probe the geometry and energetics of the system. Orbital modulations of the high-energy component can be distinguished from these of photo absorption by the four large size telescopes of the Cherenkov Telescope Array to be placed in the southern hemisphere. e-Astrogam could easily discriminate between the lepto-hadronic and the hadronic models for the gamma-ray emission and constrain acceleration physics in more extreme conditions than found in SNR.

The 34th International Cosmic Ray Conference : ICRC2015 : 30 July- 6 August, 2015, The Hague, The Netherlands / IUPAP The 34th International Cosmic Ray Conference, ICRC2015, The Hague, Netherlands, 30 Jul 2015 - 6 Aug 2015; Trieste, Italy : Sissa Medialab srl, Proceedings of science 236, 707 pp. (2016). doi:10.22323/1.236.0707, Published by Sissa Medialab srl, Trieste, Italy

The data acquisition system (DAQ) of the future Cherenkov Telescope Array (CTA) must be ef- ficient, modular and robust to be able to cope with the very large data rate of up to 550 Gbps coming from many telescopes with different characteristics. The use of modern middleware, namely ZeroMQ and Protocol Buffers, can help to achieve these goals while keeping the development effort to a reasonable level. Protocol Buffers are used as an on-line data for- mat, while ZeroMQ is employed to communicate between processes. The DAQ will be controlled and monitored by the Alma Common Software (ACS). Protocol Buffers from Google are a way to define high-level data structures through an in- terface description language (IDL) and a meta-compiler. ZeroMQ is a middleware that augments the capabilities of TCP/IP sockets. It does not implement very high-level features like those found in CORBA for example, but makes use of sockets easier, more robust and almost as effective as raw TCP. The use of these two middlewares enabled us to rapidly develop a robust prototype of the DAQ including data persistence to compressed FITS files., In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.05894

We present a study of the average hard X-ray spectra of Seyfert galaxies accumulating 100 Ms of INTEGRAL observing time. Our aim is to test the unified model of Active Galactic Nuclei, and to constrain differences and similarities between different classes of objects. We analysed all public INTEGRAL IBIS/ISGRI data available on 165 Seyfert galaxies detected at z < 0.2. Our final sample consists of 44 Seyfert 1, 29 Seyfert 1.5, 78 Seyfert 2, and 14 Narrow Line Seyfert 1. For each subsample, we stacked all the images, and derived their average hard X-ray spectra in the 17-250 keV energy range. All classes of Seyfert galaxies show on average the same nuclear continuum, as foreseen by the zeroth order unified model. The average spectrum of midly obscured Seyfert 2s is different, featuring a broad excess of emission at 30 keV that we interpret as a strong reflection component. This correlation between reflection and absorption suggests that the Seyfert type is determined by the environment rather than by inclination. Furthermore this large reflection component might reduce the amount of Compton-thick objects needed to explain the peak of the cosmic X-ray background. A simple fit to the CXB shows that our findings might imply that the fraction of Compton-thick sources is not larger than 10%.

Eta Carinae is the colliding wind binary with the largest mass loss rate in our Galaxy and the only one in which hard X-ray emission has been detected. Eta Carinae is therefore a primary candidate to search for particle acceleration by probing its gamma-ray emission. We used the first 21 months of Fermi/LAT data to extract gamma-ray (0.2-100 GeV) images, spectra and light-curves, then combined them with multi-wavelength observations to model the non-thermal spectral energy distribution. A bright gamma-ray source is detected at the position of eta Carinae. Its flux at a few 100 MeV corresponds very well to the extrapolation of the hard X-ray spectrum towards higher energies. The spectral energy distribution features two distinct components. The first one extends over the keV to GeV energy range, and features an exponential cutoff at 1 GeV. It can be understood as inverse Compton scattering of ultraviolet photons by electrons accelerated up to g 10 4 in the colliding wind region. The second component is a hard gamma-ray tail detected above 20 GeV. It could be explained byp 0 -decay of accelerated hadrons interacting with the dense stellar wind. The ratio between the fluxes of the p 0 and inverse Compton components is roughly as predicted by simulations of colliding wind binaries. This hard gamma-ray tail can only be understood if emitted close to the wind collision region. The energy transferred to the accelerated hadrons ( 5% of the collision mechanical energy) is comparable to that of the thermal X-ray emission.

The synthesis of the cosmic X-ray background requires a large population of Compton thick Active Galactic Nuclei that has not been detected so far. We probe whether bright infrared galaxies could arbor a population of Compton thick nuclei and if they could contribute significantly. We analysed 100 Msec of INTEGRAL observations obtained on 613 galaxies from the IRAS Revised Bright Galaxy Sample. We derived the average hard X-ray emission of Seyfert and various non Seyfert galaxy subsamples to estimate their contribution to the hard X-ray background. The Seyfert 1 & 2 are clearly detected at hard X-rays. None of the other galaxy subsamples is detected. The upper limit obtained for non Seyfert galaxies is as low as 7×10−13 erg s−1 cm−2. ULIRGs are at least 5 times under-luminous at hard X-rays when compared to Seyferts. On average non Seyfert galaxies do not contain active nuclei brighter than 1041 erg/s at hard X-rays. 64% of the hard X-ray emission from the sample originates in absorbed active nuclei. Non-Seyfert galaxies contribute for less than 7% and do not arbor the Compton thick nuclei required to synthesize the X-ray background.

We report the detection of the radio galaxy M87 in the 20-60 keV energy band by INTEGRAL. The detected flux cannot be explained by the high-energy tail of the thermal X-ray emission from the core of Virgo cluster. The signal can also not be explained by non-thermal emission from the nucleus and kpc-scale jet of M87 in quiescence. We argue that plausible explanations of the observed flux could be the HST-1 knot when flaring or the extended non-thermal emission from the large-scale radio halo of M87. These two alternate explanations can be tested with future monitoring of the source with INTEGRAL.