Master Thesis defense by Mette Vindbæk Madsen & Charlie Meinertz
Title: EXTREME EMISSION LINES IN THE ULTRAVISTA FIELD
Abstract: The COSMOS2020 catalogue, including UltraVISTA DR4, contains over 1.7 million galaxies observed in the ˜2 deg2 equatorial COSMOS field. The data includes photometric values and derived properties using photometric analyses with the EAZY and Le PHARE SED-fitting tools. Using the included UltraVISTA narrowband observations with the NB118 filter centered at 11850 Å we select candidates in the field with narrowband excess mag(J - NB118)correction > 1 and identify which of the possible emission lines is observed and investigate additional properties of the host galaxies. Possible emission lines include Hα at z = 0.81, [OIII] at z = 1.38, Hβ at z=1.45 and [OII] at z = 2.19. There are further possibilities but these are the lines we focus on in this work, as they are the most likely to make our color excess criteria. We use both EAZY and theoretical models from GALEV to derive properties of our candidates and present them including some we would consider for follow-up observations obtaining spectra for further analysis. Amongst these are several groupings or small clusters of candidates containing three or more within 50 arc seconds of each other and at the same redshift. The photometric data was not sufficient to distinguish between the doublets for [OII] and [OIII] although for [OIII] the 3:1 ratio makes it most likely to be the 5007 Å, and we were also unable to distinguish between [OIII] and Hβ, so we grouped them together. We present 378 color excess selected candidates, which we categorize as 51 ( 13.5%)Hα , 68 ( ˜18%)[OII], and 259 (˜68.5% )[OIII]=Hβ. Emission lines range in equivalent width from ˜ 150 to ˜ 2000Å, and using IR photometry we find stellar masses from 107M Θ to 1011M Θ.
Supervisor
Johan Peter Uldall Fynbo, University of Copenhagen, Niels Bohr Insitute
Censor:
Frank Grundahl, Aarhus University
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ZOOM-link for safety regarding COVID-19:
https://ucph-ku.zoom.us/j/62108912234?pwd=K2I3ZXlTWlV0SUdBdUl1WEFTeWRVQT09
Meeting ID: 621 0891 2234
Passcode: 240395