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Αρχική    UV and optical cross correlation studies of AGN at different time-scales  

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Τίτλος UV and optical cross correlation studies of AGN at different time-scales
Συγγραφέας Λάγγης, Δημήτριος-Αλκίνοος
Σύμβουλος διατριβής Παπαδάκης, Ιωσήφ
Περίληψη An active galactic nucleus (AGN) is an extremely bright compact central region of a galaxy, emitting substantial amounts of energy that spans across the entire electromagnetic spectrum. These objects have characteristics that indicate it would be impossible for their luminosity to be produced by stars. Moreover, AGN are the most luminous persistent sources of electromagnetic radiation in the universe, with typical bolometric luminosity around ~1042 to ~1048 ergs per second, with their visible emitting area being not much larger than the size of our solar system. For example, the bolometric luminosity of a quasar, which is the most luminous type of AGN, is ~1043 to ~1048 ergs per second, while the respective luminosity of their host galaxy is ~1042 to ~1044 ergs per second, meaning that in a lot of cases AGN outshine their host galaxy. It is estimated that around 10-20% of the galaxies in our local universe host an AGN. In this work, our first objective is to quantitatively investigate the phenomena of the negative time lags present in the slow variations of Fairall9. To do that, we are going to determine the longest sampled timescale by applying the discrete Fourier transform to the light curves across all the wavebands. Then, we will calculate the delays between the wavebands in a quantitative way by applying methods that are described below. Our second objective is to repeat the same analysis using data for many AGN, in order to study the behaviour of their slow variations and see whether the presence of negative time lags in the long term variations in AGN is common or not.
Γλώσσα Αγγλικά
Ημερομηνία έκδοσης 2023-11-22
Συλλογή   Σχολή/Τμήμα--Σχολή Θετικών και Τεχνολογικών Επιστημών--Τμήμα Φυσικής--Πτυχιακές εργασίες
  Τύπος Εργασίας--Πτυχιακές εργασίες
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