Graduate theses
Current Record: 77 of 179
|
Title |
Searching for Wolf – Rayet X-ray binaries in six nearby starburst galaxies |
Author
|
Ψαρράς, Κωνσταντίνος
|
Thesis advisor
|
Ζέζας, Ανδρέας
|
Abstract |
In this work, we present a study of the optical counterparts of the X-ray sources in six nearby
starburst galaxies, and we combine data from the Chandra X-ray source catalogue and the Hubble
Source catalogue. Moreover, they are nearby, so we can detect individual bright stars. First, we
cross-correlate the very massive early-type stars with the X-ray sources, for 0.5 arcsec and 1.0
arcsec, in order to look for High-mass X-ray binaries, and more specifically for Wolf-Rayet stars as
donors. For the HST data, we use the magnitude values in B, V and I filters and we calculate the
absolute magnitudes with information given by NED – NASA/IPAC Extragalactic Database, to
create colour – magnitude diagrams for each galaxy. We show the shape of the galaxies, the position
of the X-ray sources and the position of the massive stars for the X-ray sources’ 0.5 arcsec and 1.0
arcsec error circle. Also, we quantify the chance coincidence probability for the X-ray sources that
matched with the screened optical counterparts. This way we are able to assess the reliability of the
optical matches to the X-ray sources, for each galaxy separately. Next, we discuss these results
focusing on the nature of the optical sources of the X-ray sources. Subsequently, in order to
understand their nature in a better way, we compare their location on the colour – magnitude
diagram with isochrones of different ages. We use the MIST database for v/vcrit=0.4 for HST’s
different cameras and for different values of metallicity for each galaxy. In the end, we classify the
found HXRBs, and we focus on the Wolf-Rayet X-ray binaries candidates and the properties of the
optical counterparts that account for Wolf-Rayet stars.
|
Language |
English |
Issue date |
2022-04-01 |
Collection
|
School/Department--School of Sciences and Engineering--Department of Physics--Graduate theses
|
|
Type of Work--Graduate theses
|
Permanent Link |
https://elocus.lib.uoc.gr//dlib/3/8/a/metadata-dlib-1648645054-794623-19142.tkl
|
Views |
383 |