title: Star Formation in the COSMOS Field : A radio view on the build-up of stellar mass over 12 billion years
creator: Karim, Alexander
subject: ddc-520
subject: 520 Astronomy and allied sciences
description: In this thesis I study the evolution of galaxies with a special focus on their star forming ability by using the extensive multi-wavelength data sets available for the 2 square degree COSMOS deep field. The deep radio continuum data from Very Large Array observations at a frequency of 1.4 GHz (a wavelength of 20 cm) form the basis of my analysis of the cosmic star formation history unaffected by dust obscuration. A newly developed stacking algorithm enabled an unprecedentedly representative view on the evolution of the average star formation rate within galaxies down to low limiting (stellar) masses since a redshift of z~3 (i.e. ~2 billion years after the Big Bang). My findings are in good agreement with results from different star formation diagnostics that often suffer from large dust corrections or significantly worse statistics. A main result of this thesis is the identification of a constant characteristic mass for star forming galaxies. It implies that galaxies with masses similar to our Milky Way have always been the main sites of star formation. Therefore the often debated 'downsizing scenario' where the characteristic mass decreases with cosmic time is ruled out. In the young universe (<1.5 billion years of cosmic age) I successfully searched for the most extreme star forming environments. These provide critical constraints on cosmic structure formation and dust enshrouded star formation at early times. A detailed case study not only reveals large amounts of molecular gas but also a powerful hidden active galactic nucleus in one such massive starburst. This finding demonstrates the diversity of this cosmologically important galaxy population.
date: 2011
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/12776/1/thesis_subm.pdf
identifier: DOI:10.11588/heidok.00012776
identifier: urn:nbn:de:bsz:16-opus-127762
identifier:   Karim, Alexander  (2011) Star Formation in the COSMOS Field : A radio view on the build-up of stellar mass over 12 billion years.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/12776/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng