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dc.contributor.advisorMcIntosh, Daniel H.en
dc.contributor.authorHer, Xiachang
dc.date.issued2015
dc.date.submitted2015 Fallen
dc.descriptionTitle from PDF of title page, viewed on March 24, 2016en
dc.descriptionThesis advisor: Daniel McIntoshen
dc.descriptionVitaen
dc.descriptionIncludes bibliographical references (pages 93-101)en
dc.descriptionThesis (M.S.)--Department of Physics and Astronomy. University of Missouri--Kansas City, 2015en
dc.description.abstractMajor gas-poor (dry) merging between two comparably massive spheroidal galaxies are post u-lated to be the central mechanism responsible for the assembly of the most massive (M[subscript star,tot] ≥ 10¹¹ M[subscript ☉]) elliptical galaxies. Numerical simulations predict that these mergers may occur at late cosmic times and typically in dense environments. Previous work based on a complete sample of high-mass (M[subscript star] ≥ 5 x 10¹⁰ M[subscript ☉]) galaxies with z ≤ 0.12 selected from the Yang et al. (2007) SDSS Galaxy Group Catalog and analyzed for residual asymmetric features in SDSS r-band images provided a lower limit to the frequency of massive pairs with interaction signatures residing in groups and clusters with halo masses M[subscript halo] ≥ 2.5 x 10¹³ M[subscript ☉]. The tidal sgnatures of such interactions may often be too faint to be clearly detected at the sensitivity of SDSS imaging data. To improve constraints and test the identification of dry merging, we obtained V-band images 1.5 mag deeper than SDSS for a random selection of 27 pairs with no SDSS tidal signatures, plus a subset of six previously identified interactions. Using GALFIT image residuals, we visually identify interaction signatures with surface brightnesses down to ~26.5 mag arcsec⁻² at S/N ≥ 5. We confirmed 80% of previous interaction identifications based on shallower SDSS imaging, and identified three new systems with mutual tidal signatures that were previously classified as non-interacting. Applying these deeper statistics indicates that the merger frequency for massive pairs with projected separation ≤ 30kpc increases from 16 ± 3% to 23 ± 6% combined with the shallower imaging data. The merger frequency further increases to 35 ± 16%, when the massive pairs share the same dark matter halo and have similar redshifts. We found that using SDSS alone would underestimate the merger frequency by 30%.eng
dc.description.tableofcontentsIntroduction -- Data -- Photometry -- Modeling -- Tidal parameter analysis -- Discussion -- Acknowledgments -- Appendix A. SDDS SQL query -- Appendix B. Object masking -- Appendix . Visual residual imageen
dc.format.extentviii, 102 pagesen
dc.identifier.urihttps://hdl.handle.net/10355/48344
dc.subject.lcshElliptical galaxiesen
dc.subject.otherThesis -- University of Missouri--Kansas City -- Physi s and Astronomyen
dc.titleSearching for Interacting Early Type Galaxies at Late Cosmic Timeseng
dc.typeThesiseng
thesis.degree.disciplinePhysics and Astronomyen
thesis.degree.grantorUniversity of Missouri--Kansas Cityen
thesis.degree.levelMastersen
thesis.degree.nameM.S.en


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