The gas content of luminous compact blue galaxies in the COSMOS field

Arlow, Henco

The gas content of luminous compact blue galaxies in the COSMOS field

Thesis / Dissertation

2024

Publisher

University of Cape Town

Department

Department of Astronomy

Faculty

Faculty of Science

Abstract

Luminous compact blue galaxies (LCBGs) are a heterogeneous subset of starburst galaxies. Their number density drops quite significantly as we approach lower redshifts. As a set of galaxies that evolve quickly, they make excellent candidates for studying galactic evolution as a whole. In order to understand how galaxies evolve, we make use of LCBGs to study their gas content as it changes over approximately nine billion years of lookback time. We make use of HI emission line data provided by the full CHILES survey, covering a redshift range of z=0 to z=0.45 within the COSMOS f ield as well as continuum data of the same field provided by the CHILES Continuum Polarization survey. In this thesis we set out to study the properties of LCBGs in these f ields to better understand the nature of these objects as they evolve to the present day. We report on direct detections of HI found in LCBGs in CHILES.Wealsoperform acubelet stacking technique on LCBGs for which we have known spectroscopic redshifts in CHILES. From these stacks we measure average HI masses as well as upper limit values for non-detections to study how it evolves with redshift. We also measure the star formation rates of a set of LCBGs using continuum fluxes in CHILES Con Pol and compare our results to measurements made with data from CHILES's first epoch. Continuum stacking is then performed in several redshift and stellar mass bins to extract average star formation rates. We proceed to fit appropriate functions to these relations in order to quantify the dependence of LCBG sSFRs to their stellar mass and redshift.