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Galaxies and Gas in Dark Matter Halos and the Cosmic Web

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dc.contributor.advisorHoujun Mo
dc.contributor.authorLim, Seunghwan
dc.contributor.departmentUniversity of Massachusetts Amherst
dc.date2024-03-27T20:24:04.000
dc.date.accessioned2024-04-26T15:35:29Z
dc.date.available2024-04-26T15:35:29Z
dc.date.submittedSeptember
dc.date.submitted2019
dc.description.abstractIn the current understanding of galaxy formation, galaxies are believed to form and evolve in dark matter halos. The dark matter halos are collapsed objects that form and grow via gravitational instability of small initial density fluctuation in the cosmic field. They are not only the hosts of galaxies but are tracers of the cosmic web of the Universe. They are thus crucial components for understanding how galaxies form and evolve within the cosmic web. This dissertation is a systematic investigation of the galaxies and gas in the dark matter halos and the cosmic web, using observation data of large galaxy surveys such as the Sloan Digital Sky Survey (SDSS), and of the Cosmic Microwave Background (CMB) survey such as the Planck, together with simulations and modellings for comparison and interpretation. Specifically, we have identified dark matter halos in the low-redshift Universe, and constructed the largest to date all-sky group catalog. We also investigated correlations between many of the galaxy and halo properties, particularly finding, for the first time, an observational proxy of halo age. Then, I developed a series of novel approaches to maximize the detection of the Sunyaev-Zel'dovich effect (SZE), and from it explored the gas properties in halos to find that the gas mass fraction even in Milky Way-size halos is about the cosmic mean fraction. The analysis identified the baryons in a warm-hot medium on halo scales. We also show that the thermal SZE can be used to constrain the mean relationship between thermal energy of IGM gas and local total matter density for the first time. We support the reliability of our methods and results with tests where the methods are applied to the mock CMB maps constructed from simulations. Finally, we present comparisons with simulations of the SZE, and discuss the implications for its constraining power of galaxy formation models.
dc.description.degreeDoctor of Philosophy (PhD)
dc.description.departmentAstronomy
dc.identifier.doihttps://doi.org/10.7275/14961611
dc.identifier.orcidhttps://orcid.org/0000-0001-6860-9064
dc.identifier.urihttps://hdl.handle.net/20.500.14394/18048
dc.relation.urlhttps://scholarworks.umass.edu/cgi/viewcontent.cgi?article=2747&context=dissertations_2&unstamped=1
dc.source.statuspublished
dc.subjectgalaxy formation
dc.subjectdark matter halos
dc.titleGalaxies and Gas in Dark Matter Halos and the Cosmic Web
dc.typeopenaccess
dc.typearticle
dc.typedissertation
digcom.contributor.authorisAuthorOfPublication|email:shlim1206@gmail.com|institution:University of Massachusetts Amherst|Lim, Seunghwan
digcom.identifierdissertations_2/1791
digcom.identifier.contextkey14961611
digcom.identifier.submissionpathdissertations_2/1791
dspace.entity.typePublication
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