1. The Cherenkov Telescope Array performance in divergent modeA. Donini, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, objavljeni znanstveni prispevek na konferenci Opis: Two of the Key Science Projects of the Cherenkov Telescope Array (CTA) consist in performing a deep survey of the Galactic and Extragalactic sky, providing an unbiased view of the Universe at energies above tens of GeV. To optimize the time spent to perform the Extragalactic survey, a so-called “divergent mode” of the CTA was proposed as an alternative observation strategy to the traditional parallel pointing in order to increase its instantaneous field of view. The search for transient VHE sources would also benefit from an extended field of view. In the divergent mode, each telescope points to a position in the sky that is slightly offset, in the outward direction, from the center of the field of view. In this contribution, we present the first performance estimation from full Monte Carlo simulation of possible CTA divergent mode setups.
Ključne besede: very-high-energy gamma rays, Cherenkov Telescope Array (CTA) Observatory, CTAO Key Science Projects (KSPs), galactic survey KSP, extragalactic survey KSP
Objavljeno v RUNG: 15.11.2024; Ogledov: 455; Prenosov: 4
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2. Cherenkov Telescope Array potential in the search for Galactic PeVatronsE.O. Angüner, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, objavljeni znanstveni prispevek na konferenci Opis: One of the major scientific objectives of the future Cherenkov Telescope Array (CTA) Observatory is the search for PeVatrons. PeVatrons are cosmic-ray factories able to accelerate nuclei at least up to the knee feature seen in the spectrum of cosmic rays measured near the Earth. CTA will perform a survey of the full Galactic plane at TeV energies and beyond with unprecedented sensitivity. The determination of efficient criteria to identify PeVatron candidates during the survey is essential in order to trigger further dedicated observations. Here, we present results from a study based on simulations to determine these criteria. The outcome of the study is a PeVatron figure of merit, defined as a metric that provides relations between spectral parameters and spectral cutoff energy lower limits. In addition, simulations of the PeVatron candidate HESS J1641−463 and its parental particle spectrum are presented and discussed. Eventually, our work is applied to simulated population of Galactic PeVatrons, with the aim to determine the sensitivity of CTA.
Ključne besede: Galactic cosmic rays, very-high-energy gamma rays, Galactic PeVatrons, Cherenkov Telescope Array (CTA) Observatory, Galactic plane survey, H.E.S.S. J1641−463 PeVatron candidate
Objavljeno v RUNG: 08.11.2024; Ogledov: 383; Prenosov: 5
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3. Prospects for a survey of the galactic plane with the Cherenkov Telescope ArrayK. Abe, Saptashwa Bhattacharyya, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2024, izvirni znanstveni članek Opis: Approximately one hundred sources of very-high-energy (VHE) gamma rays are known in the Milky Way, detected with a combination of targeted observations and surveys. A survey of the entire Galactic Plane in the energy range from a few tens of GeV to a few hundred TeV has been proposed as a Key Science Project for the upcoming Cherenkov Telescope Array Observatory (CTAO). This article presents the status of the studies towards the Galactic Plane Survey (GPS). We build and make publicly available a sky model that combines data from recent observations of known gamma-ray emitters with state-of-the-art physically-driven models of synthetic populations of the three main classes of established Galactic VHE sources (pulsar wind nebulae, young and interacting supernova remnants, and compact binary systems), as well as of interstellar emission from cosmic-ray interactions in the Milky Way. We also perform an optimisation of the observation strategy (pointing pattern and scheduling) based on recent estimations of the instrument performance. We use the improved sky model and observation strategy to simulate GPS data corresponding to a total observation time of 1620 hours spread over ten years. Data are then analysed using the methods and software tools under development for real data. Under our model assumptions and for the realisation considered, we show that the GPS has the potential to increase the number of known Galactic VHE emitters by almost a factor of five. This corresponds to the detection of more than two hundred pulsar wind nebulae and a few tens of supernova remnants at average integral fluxes one order of magnitude lower than in the existing sample above 1 TeV, therefore opening the possibility to perform unprecedented population studies. The GPS also has the potential to provide new VHE detections of binary systems and pulsars, to confirm the existence of a hypothetical population of gamma-ray pulsars with an additional TeV emission component, and to detect bright sources capable of accelerating particles to PeV energies (PeVatrons). Furthermore, the GPS will constitute a pathfinder for deeper follow-up observations of these source classes. Finally, we show that we can extract from GPS data an estimate of the contribution to diffuse emission from unresolved sources, and that there are good prospects of detecting interstellar emission and statistically distinguishing different scenarios. Thus, a survey of the entire Galactic plane carried out from both hemispheres with CTAO will ensure a transformational advance in our knowledge of Galactic VHE source populations and interstellar emission.
Ključne besede: very-high-energy gamma rays, Cherenkov Telescope Array Observatory, CTAO Galactic Plane Survey, galactic cosmic rays, pulsar wind nebulae, supernova remnants, galactic PeVatrons, binary systems, diffuse emission
Objavljeno v RUNG: 28.10.2024; Ogledov: 527; Prenosov: 0
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5. Probing the fundamental nature of Dark Matter with the Large Synoptic Survey Telescope : v1.1Alex Drlica-Wagner, Yao-Yuan Mao, Susmita Adhikari, Robert Armstrong, Arka Banerjee, Nilanjan Banik, Keith Bechtol, Simeon Bird, Christopher Eckner, Gabrijela Zaharijas, 2019, projektna dokumentacija (idejni projekt, izvedbeni projekt) Ključne besede: dark matter, high energy physics, astrophysical observations, cosmological observations, Large Synoptic Survey Telescope (LSST)
Objavljeno v RUNG: 03.05.2022; Ogledov: 3162; Prenosov: 46
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7. Searching for PeVatrons in the CTA Galactic Plane SurveyC. Trichard, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, 2017, objavljeni znanstveni prispevek na konferenci Ključne besede: Cherenkov Telescope Array, Galactic Plane Survey, cosmic PeVatrons
Objavljeno v RUNG: 16.02.2018; Ogledov: 4390; Prenosov: 136
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8. Simulations of Tidal Disruption Events Observations with the LSSTKatja Bricman, 2017, magistrsko delo Opis: The Large Synoptic Survey Telescope (LSST) will produce a multi-colour survey of 25000 square deg of the Southern sky during its 10 years of operations. It will observe over 20 billion galaxies and a similar number of stars, map the Solar System and the Milky Way, and probe dark matter and dark energy. In addition, it will discover thousands of transients every night, including new classes of objects, which have not yet been observed. Due to its large coverage of the sky it will be a perfect tool for the search of rare Tidal Disruption Events (TDEs), which occur when a star passes close by a supermassive black hole and gets disrupted by its tidal force. Afterwards the stellar debris fall back to the black hole, initially at a rate exceeding
the Eddington rate, producing an outflow, which releases a flare of energy. When the fallback rate subsides below the Eddington rate, the gas accretes onto the black hole via accretion disk. The LSST simulation framework enables us to simulate observations of different types of objects with the LSST. In this work, we include TDEs in the LSST simulation framework, estimate the number of detected TDEs, and simulate their light curves using a theoretical model, which predicts a t^(-2.6) light curve decline with time in the outflow phase and a t^{-0.4} decline in the disk phase. We also take a closer look at the distribution of the detected TDEs over cosmological redshift and black hole mass.
Ključne besede: Astronomical observations, Large Synoptic Survey Telescope, Tidal Disruption Events, Black Holes, simulations
Objavljeno v RUNG: 17.10.2017; Ogledov: 5234; Prenosov: 0
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