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The Galaxy Morphology-Density Relation at High Redshift with CANDELS

Kodra, Dritan (2019) The Galaxy Morphology-Density Relation at High Redshift with CANDELS. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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One of the biggest open questions regarding the evolution of the galaxy population over time, is how their properties (such as their morphologies) are affected by their local environment, e.g. the density of matter in the region where they are found. In the local universe, studies have shown that elliptical galaxies are found predominantly in the central regions of galaxy clusters where densities are higher, while disk galaxies reside in regions of lower densities such as the edges of clusters and the low-density "field". We investigate if this pattern continues to exist at earlier times by using data from the CANDELS collaboration at redshifts up to $z \sim 3$. For this, we make use of photometric redshift probability distributions (photo-z PDFs) for the galaxies observed by CANDELS. This required the development of new statistical methods to improve the quality of the PDFs measured by the CANDELS team, described in the thesis. We have used 3D-HST grism redshifts as well as spectroscopic redshifts where available, to test and optimize techniques for combining PDFs determined from multiple methods. We use morphological catalogs provided by the CANDELS team to select galaxies from three main categories: spheroid, disk, and irregular galaxies. We investigate the relative clustering of these different morphological types by estimating two-point cross correlation functions of each type with the full sample of CANDELS galaxies. Our results show that spheroid galaxies still cluster more strongly than disk galaxies at small separations at higher redshifts, while at larger separations the difference in their clustering amplitudes is not statistically significant. At the highest redshifts studied, clustering measurements are too noisy to detect differences in clustering strength, if any persist.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Kodra, Dritandrk36@pitt.edudrk360000-0002-8824-5509
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairNewman,
Committee MemberKosowsky,
Committee MemberLeibovich,
Committee MemberWood-Vasey,
Committee MemberLee,
Date: 30 January 2019
Date Type: Publication
Defense Date: 25 April 2018
Approval Date: 30 January 2019
Submission Date: 6 December 2018
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 163
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: galaxies: clusters: general galaxies: distances and redshifts galaxies: formation galaxies: evolution galaxies: high-redshift galaxies: statistics
Related URLs:
Date Deposited: 30 Jan 2019 23:26
Last Modified: 29 Jul 2019 15:48


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