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On Dark Matter Halos and Their Connection to Galaxies

Wang, Kuan (2021) On Dark Matter Halos and Their Connection to Galaxies. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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In the concordance model of modern cosmology, dark matter is five times as abundant as ordinary matter.
While its nature remains one of the most challenging questions in today’s physics, dark matter has been established as a defining factor in the large-scale structure.
Visible galaxies form in the potential wells of dark matter density peaks, known as halos.
Empirical galaxy–halo connection models, which reconstruct the observable components of the Universe from theory of the dark sector, are broadly used for their simplicity and effectiveness.
The fundamental premise of empirical models is the statistical dependence of galaxy properties on halo properties, the latter of which are easily accessible through simulations.

With tremendous amounts of data being produced by new surveys, theoretical tools need also be further developed to exploit the full potential of data.
In particular, small-scale observables, which require detailed knowledge of halos and the connection between galaxies and halos, are a promising source of information for constraining cosmology and galaxy physics.
It is urgent and important in the new era of precision cosmology to improve models of these factors.

This thesis aims to improve our understanding of dark matter halo evolution and the dependence of galaxies on the halos in which they reside.
In the first part, we investigate how the present-day halo structure emerges from the halo mass assembly history, and characterize respective contributions from pseudo-evolution and physical merger events.
We uncover the significant impact of mergers on the evolution of halo structure, and recognize universal patterns in mergers.
These findings will also shed light on the galaxy evolution in halos.
In the second part, we test the validity of the simplifying assumptions adopted in galaxy–halo connection models.
We identify the optimal combination of observable statistics that contain the most information on the galaxy–halo connection, and obtain observational constraints on the model using these statistics.
We observationally confirm that the inclusion of galaxy count statistics significantly improves the constraining power, and find definitive evidence that the galaxy–halo connection depend on secondary halo properties besides mass.
These results inform the physics of galaxy formation and evolution and cosmological inferences.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Wang, Kuankuw8@pitt.edukuw80000-0001-7690-2260
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairZentner, Andrew R.zentner@pitt.eduzentner
Committee MemberBatell, Brianbatell@pitt.edubatell
Committee MemberKosowsky, Arthur K.arthurk@pitt.eduarthurk
Committee MemberNewman, Jeffrey A.janewman@pitt.edujanewman
Committee MemberMandelbaum,
Date: 8 October 2021
Date Type: Publication
Defense Date: 8 July 2021
Approval Date: 8 October 2021
Submission Date: 28 July 2021
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 170
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: Galaxy assembly bias; Galaxy–halo connection; Dark matter halos
Date Deposited: 08 Oct 2021 19:43
Last Modified: 08 Oct 2021 19:43


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