The evolution of galaxies in the Hubble Deep Fields
| dc.contributor.author | Gwyn, Stephen Donald Jermy | |
| dc.contributor.supervisor | Hartwick, F. D. A. | |
| dc.date.accessioned | 2018-11-16T19:10:43Z | |
| dc.date.available | 2018-11-16T19:10:43Z | |
| dc.date.copyright | 2001 | en_US |
| dc.date.issued | 2018-11-16 | |
| dc.degree.department | Department of Physics and Astronomy | en_US |
| dc.degree.level | Doctor of Philosophy Ph.D. | en_US |
| dc.description.abstract | This thesis is a study of several aspects of the evolution of galaxies using photometric redshifts in the Hubble Deep Fields (HDF's). The photometric redshift method is used in the HDF's down to a magnitude limit of I = 28. The large sample and the unprecedented depth of the Hubble Deep Fields allow one to trace the evolution of several properties of galaxies from z = 5 to the present in a statistical manner. This thesis studies four such aspects: (1) The clustering of galaxies is examined. When the redshift distributions of the HDF-North and the HDF-South are compared, one finds a significantly greater number of galaxies around z = 0.5. This suggests the presence of a structure (a very weak cluster or a very strong group) in the HDF-North. (2) The star formation rate density (SFRD) is determined by measuring the UV-luminosity density. After correcting for dust extinction, the star formation rate is found to decrease exponentially with time with an e-folding period of about 4 Gyr. (3) The difference between the rate of declines of the B band galaxy number density and the luminosity densities are used to examine the merging history of the Universe. While the total B band luminosity density of the Universe decreases only slightly with time since z = 5, the number density of galaxies drops considerably more. On average, a present day galaxy is the product of ∼3 progenitors. (4) The morphology of galaxies is quantified using a “lumpiness” parameter, L, which measures the number of local maxima in the image of a galaxy. Rest-frame B band images are made of both HDF's by k-correcting each pixel of each galaxy in the frames using the photometric redshifts of the parent galaxies. It is found that L increases with increasing absolute brightness and increasing redshift, albeit only slightly. | en_US |
| dc.description.scholarlevel | Graduate | en_US |
| dc.identifier.uri | http://hdl.handle.net/1828/10315 | |
| dc.language | English | eng |
| dc.language.iso | en | en_US |
| dc.rights | Available to the World Wide Web | en_US |
| dc.subject | Photometric redshifts | en_US |
| dc.subject | Galaxies | en_US |
| dc.subject | Pure sciences | en_US |
| dc.title | The evolution of galaxies in the Hubble Deep Fields | en_US |
| dc.type | Thesis | en_US |