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Identifier 000437567
Title Measuring star-formation rates in galaxies and their correlation with X-ray emission
Alternative Title Μέθοδοι μέτρησης του ρυθμού αστρογένεσης γαλαξιών και η συσχέτισή τους με την ακτινοβολία ακτίνω X
Author Κουρουμπατζάκης, Κωνσταντίνος
Thesis advisor Ζέζας, Ανδρέας
Reviewer Χαρμανδάρης, Βασίλης
Παυλίδου, Βασιλική
Παπαδάκης, Ιωσήφ
Reig. Pablo
Diaz Santos. Tanio
Ξυλούρης, Μανόλης
Abstract We present a study of different star-formation rate (SFR) indicators, focusing on Hα emission, and its comparison with other SFR tracers. We present Hα photometry and provide calibrations of Hα-based SFRs for the Star-Formation Reference Survey (SFRS), a representative sample of star-forming galaxies in the local Universe. We explore the effect of extinction correction based on the Balmer decrement, infrared excess (IRX), and fits of spectral energy distributions (SEDs), as well as, corrections for the contribution of the [NII] lines emission. We provide a functional description between extinction and metallicity. For a subset of the SFRS sample with good quality X-ray data, we explore the connection between SFR and X-ray luminosity (LX) in sub-galactic scales. There is good agreement with established LX–SFR relations down to SFR≃10-3 Myr-1, below which an excess in X-ray luminosity emerges which likely arises from low-mass X-ray binaries. The SFR derived from Hα shows the tightest correlation with X-ray luminosity because Hα emission probes stellar populations with ages similar to HMXB formation timescales. In order to explore the effect of metallicity on the X-ray luminosity–SFR relation, we present a systematic study of the metallicity variations within the collisional ring galaxy NGC 922, based on long-slit spectroscopic, X-ray, and IR observations. We find a metallicity difference between star-forming regions in the bulge and the ring, with metallicities ranging from almost solar to significantly sub-solar ([12 + log(O/H)]≃8.2). We find an anti-correlation between the X-ray luminosity and metallicity of the sub-galactic regions of NGC 922. The different regions have similar stellar population ages leaving metallicity as the main driver of the anti-correlation.
Language English
Subject Galaxies
Star formation
X-Ray binaries
Δυαδικά συστήματα ακτίνων X
Θόρυβος σπιν
Issue date 2021-03-10
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
  Type of Work--Doctoral theses
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