The Dark Matter Problem in Rotationally Supported Galaxies

Bibliographic Details
Main Author:	Li, Pengfei
Language:	English
Published:	Case Western Reserve University School of Graduate Studies / OhioLINK 2020
Subjects:	Astronomy Astrophysics
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=case159440473976029

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-case1594404739760292021-08-03T07:15:41Z The Dark Matter Problem in Rotationally Supported Galaxies Li, Pengfei Astronomy Astrophysics Different lines of evidence suggest that the observed dynamics of galaxies, galaxy clusters, and the Universe as a whole cannot be explained by the visible, baryonic matter when applying the standard laws of Gravity. Two competing solutions have been proposed and hotly debated in the past decades: introduce dark matter (DM) or modify the laws of gravity. In this dissertation, I present a systematic investigation of these two hypothesis using 175 late-type galaxies from the Spitzer Photometry \& Accurate Rotation Curves (SPARC) database.On the DM front, I fit the SPARC rotation curves testing seven different halo profiles. Based on these fits, I explore the correlations between DM halos and stellar disks, and find that the characteristic volume density of DM halos is remarkably constant over 5 decades in galaxy luminosity. This serves as a testing bed for galaxy formation models. Using the correlation between DM halo masses and \hi\ line widths, I measure for the first time the DM halo mass function (HMF). The measured HMF agrees with the prediction of DM-only simulations at intermediate and low halo masses, but differs significantly at high mass end. Finally I compute the effect of adiabatic compression on the DM halos due to the baryonic gravitational potential, and find that compressed halos contribute more to rotation curves, exacerbating the core-cusp problem over the whole range of galaxy masses.On the modified gravity front, I test the statistically established radial acceleration relation (RAR) which indicates a strong link between the baryonic mass distribution and the observed dynamics of galaxies. The vast majority of the SPARC galaxies can be well described by the RAR. The best-fit RAR has an rms scatter of 0.057 dex, comparable to the observational uncertainties on rotation curves. This leaves little room for intrinsic scatter if any. I check the critical acceleration scale in the RAR is universal among late-type galaxies, marking no difference between the RAR and the Modified Newtonian Dynamics. Overally, Modified Newtonian Dynamics can describe disk galaxies with less problems than DM models, but a comprehensive evaluation requires the systematic investigations on galaxy-cluster and cosmological scales. 2020-09-07 English text Case Western Reserve University School of Graduate Studies / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=case159440473976029 http://rave.ohiolink.edu/etdc/view?acc_num=case159440473976029 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Astronomy Astrophysics
spellingShingle	Astronomy Astrophysics Li, Pengfei The Dark Matter Problem in Rotationally Supported Galaxies
author	Li, Pengfei
author_facet	Li, Pengfei
author_sort	Li, Pengfei
title	The Dark Matter Problem in Rotationally Supported Galaxies
title_short	The Dark Matter Problem in Rotationally Supported Galaxies
title_full	The Dark Matter Problem in Rotationally Supported Galaxies
title_fullStr	The Dark Matter Problem in Rotationally Supported Galaxies
title_full_unstemmed	The Dark Matter Problem in Rotationally Supported Galaxies
title_sort	dark matter problem in rotationally supported galaxies
publisher	Case Western Reserve University School of Graduate Studies / OhioLINK
publishDate	2020
url	http://rave.ohiolink.edu/etdc/view?acc_num=case159440473976029
work_keys_str_mv	AT lipengfei thedarkmatterprobleminrotationallysupportedgalaxies AT lipengfei darkmatterprobleminrotationallysupportedgalaxies
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The Dark Matter Problem in Rotationally Supported Galaxies

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