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Identifier

000467901

Title

X-ray variability studies of accreting compact objects

Alternative Title

Μελέτη μεταβλητότητας ακτίνων-Χ σε ενεργούς γαλαξίες και διπλά αστρικά συστήματα ακτίνων-Χ

Author

Μπίνας Βαλαβάνης, Βασίλειος Κ.

Thesis advisor

Παπαδάκης, Ιωσήφ

Reviewer

Κυλάφης, Νικόλαος
Reig, Pablo

Abstract

We study the X-ray variability of Black Hole Binaries (BHBs) and compare it with the X-ray variability of Active Galactic Nuclei (AGN). For that purpose, we conduct a comparison of power spectral densities (PSDs) between BHBs and AGN, using observations in the same energy band. We chose to study BHBs in their hard state, with the exception of Cygnus X-1, for which we analysed both the hard and soft states. In order to achieve our goal, we used the Papadakis & Binas-Valavanis (2024) results for AGN, which were based on the analysis of observations in the 14-195 keV band. As for the BHB sample, we selected three well studied sources and decided to use light curves from the Hard X-ray Modulation Telescope (HXMT). HXMT was the perfect satellite for our analysis, since it could provide us with data of BHBs in the 15-30 keV and 30-100 keV bands. We used the HXMT light curves to compute the PSDs of the selected BHBs and compared them to the AGN PSD. We found that only one observation of one source had identical PSD with that of the AGN. That source was Cygnus X-1 and during that observation the BHB was in its soft state. Furthermore, we found that Cygnus X-1 in its soft state had a very similar energy spectrum to that of a typical AGN. Thus, AGN and Cygnus X-1 in its soft state have identical energy and power spectra. Since AGN and Cygnus X-1 in its soft state have the same spectral and timing properties, the physical processes and the disk/corona geometry should be identical in both systems.

Language

English

Subject

AGN

Astrophysics

High energy astrophysical phenomena

X-ray binaries

Αστροφυσικά φαινόμενα υψηλών ενεργειών

Αστροφυσική

Ενεργειακή γαλαξίες

Issue date

2024-11-21