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Opis: The TeV extragalactic sky is dominated by blazars, radio-loud active galactic nuclei with a relativistic jet pointing towards the Earth. Blazars show variability that can be quite exceptional both in terms of flux (orders of magnitude of brightening) and time (down to the minute timescale). This bright flaring activity contains key information on the physics of particle acceleration and photon production in the emitting region, as well as the structure and physical properties of the jet itself. The TeV band is accessed from the ground by Cherenkov telescopes that image the pair cascade triggered by the interaction of the gamma ray with the Earth’s atmosphere. The Cherenkov Telescope Array (CTA) represents the upcoming generation of imaging atmospheric Cherenkov telescopes, with a significantly higher sensitivity and larger energy coverage with respect to current instruments. It will thus provide us with unprecedented statistics on blazar light-curves and spectra. In this contribution we present the results from realistic simulations of CTA observations of bright blazar flares, taking as input state-of-the-art numerical simulations of blazar emission models and including all relevant observational constraints.
Ključne besede: active galactic nuclei (AGN), radio-loud AGN, blazars, blazar flares, cosmic particle acceleration, very-high-energy gamma-rays, Cherenkov Telescope Array
Objavljeno v RUNG: 15.09.2023; Ogledov: 87; Prenosov: 2
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Ključne besede: solar flares, solar gamma-ray emission, gamma-ray sources, gamma-ray telescopes, catalogs
Objavljeno v RUNG: 17.02.2022; Ogledov: 1438; Prenosov: 110
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Opis: Modern wide-field-of-view and all-sky satellites (e.g. Gaia) and ground based surveys (e.g. OGLE) repeatedly cover a large part of the sky and are detecting new, transient astrophysical sources on daily basis. In this thesis I analyzed the data from Gaia and OGLE transient surveys, with special focus on transients located near the centres of galaxies to detect possible Tidal Disruption Events. These occur when a star gets too close to a Super-Massive Black Hole, which lurks in the centres of most galaxies, and gets disrupted due to the black hole's gravitational tidal forces. The goal of my research was to detect possible Tidal Disruption Events and eliminate false candidates, such as supernovae. The work involved daily inspection of new alerts, identified with Gaia and OGLE Transient Detection System. I searched for potential transients in galactic nuclei and in case there was such a transient detected, follow-up spectroscopic observations were initiated in order to help classify the object. During the course of my work I analyzed spectra obtained with the largest telescopes in the world (SALT, VLT) and performed the spectral template matching, recognition of spectral features related to known classes of transients, determination of redshift etc.
Ključne besede: Flares, transients, Gaia, OGLE, supernovae, tidal disruption events, nuclear transients
Objavljeno v RUNG: 14.05.2019; Ogledov: 3521; Prenosov: 126
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