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The Structure & Stellar Populations of Nuclear Star Clusters in Late-Type Spiral Galaxies

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The Structure & Stellar Populations of Nuclear Star Clusters in Late-Type Spiral Galaxies UNIVERSITY OF CALIFORNIA, IRVINE The Structure & Stellar Populations of Nuclear Star Clusters in Late-Type Spiral Galaxies DISSERTATION submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Physics by Daniel J. Carson Dissertation Committee: Professor Aaron Barth, Chair Associate Professor Michael Cooper Professor James Bullock 2016 Portion of Chapter 1 c 2015 The Astronomical Journal Chapter 2 c 2015 The Astronomical Journal Chapter 3 c 2015 The Astronomical Journal Portion of Chapter 5 c 2015 The Astronomical Journal All other materials c 2016 Daniel J. Carson TABLE OF CONTENTS Page LIST OF FIGURES iv LIST OF TABLES vi ACKNOWLEDGMENTS vii CURRICULUM VITAE viii ABSTRACT OF THE DISSERTATION x 1 Introduction 1 2 HST /WFC3 data 9 2.1 SampleSelection ................................. 9 2.2 DescriptionofObservations . 10 2.3 DataReduction.................................. 14 3 Analysis of Structural Properties 17 3.1 Surface Brightness Profile Fitting . 17 3.1.1 PSFModels................................ 18 3.1.2 FittingMethod .............................. 19 3.1.3 Comparison with ISHAPE ......................... 21 3.1.4 1DRadialProfiles ............................ 22 3.1.5 Uncertainties in Cluster Parameters . 25 3.2 Results....................................... 29 3.2.1 SingleBandResults ........................... 29 3.2.2 PanchromaticResults........................... 40 3.2.3 Stellar Populations . 46 3.3 CommentsonIndividualObjects . 51 3.3.1 IC342................................... 51 3.3.2 M33 .................................... 52 3.3.3 NGC247 ................................. 53 3.3.4 NGC300 ................................. 53 3.3.5 NGC2403................................. 53 3.3.6 NGC2976................................. 54 ii 3.3.7 NGC3621................................. 55 3.3.8 NGC4244................................. 57 3.3.9 NGC4395................................. 59 3.3.10 NGC7793................................. 62 4 Analysis of Stellar Population Properties 63 4.1 GlobalSEDFits ................................. 63 4.1.1 GlobalSEDFittingMethod . .. .. 65 4.1.2 Results................................... 71 4.2 Spatially Resolved SED Fits . 81 4.2.1 Spatially Resolved SED Fitting Method . 81 4.2.2 Results................................... 83 4.3 Discussion..................................... 98 4.3.1 Comparison of Results from Global and Pixel-by-Pixel SED Fitting . 98 4.3.2 Comparison With Mass-to-Light Ratio vs. Color Relations . 100 4.3.3 CentralDensities ............................. 103 4.3.4 Old, Metal-Poor Populations . 106 4.3.5 Scaling Relations . 109 4.3.6 Mass-Metallicity Relation . 110 5 Conclusions 115 5.1 StructuralProperties .............................. 115 5.2 Stellar Population Properties . 117 5.3 FutureWork.................................... 119 Bibliography 121 A Developing and Testing the SED Fitting Code 128 A.1 ModelFittingProcedure ............................. 128 A.2 TestingtheSEDFittingMethod . 131 A.2.1 TestsonSingle-AgeModels . 133 A.2.2 Mock Catalog Based on Walcher 2006 Sample . 136 iii LIST OF FIGURES Page 2.1 HST/WFC3 filter throughput curves . 13 2.2 GrayscaleimagesofNCs ............................. 15 2.3 ColorcompositeimagesofNCs ......................... 16 3.1 TinyTim modelPSFs............................... 18 3.2 F814W GALFIT results .............................. 23 3.5 F814W GALFIT result(continued) ........................ 24 3.6 F814Wradialsurfacebrightnessprofiles . ... 26 3.6 F814W radial surface brightness profiles (continued) . ....... 27 3.6 F814W radial surface brightness profiles (continued) . ....... 28 3.7 Histograms of surface brightness profile parameters . ....... 36 3.8 ComparisonofS´ersicprofiles. 37 3.9 NC radius-luminosity relation . 38 3.10 NC vs. host luminosity relation . 39 3.11 NCeffectiveradiusvs.wavelength. .. 41 3.12 NCaxisratiovs.wavelength. 43 3.13NCvs.hostaxisratio............................... 45 3.14NCSEDs ..................................... 47 3.15 F336W F438W vs. F547M F127Mcolors ................. 49 3.16 F438W − F814W vs. F547M − F814Wcolors ................. 50 − − 3.17 NGC 4244 S´ersic parameters vs. wavelength . ..... 58 3.18 NGC4395componentSEDs ........................... 61 4.1 SSPmodelspectra ................................ 66 4.2 Example cumulative likelihood distribution . 69 4.3 Globalbest-fitSEDs ............................... 72 4.4 NCStarFormationRates ............................ 76 4.5 Pixel-by-pixel SED fit results . 84 4.5 Pixel-by-pixel SED fit results (continued) . ... 85 4.6 Reddeningmaps ................................. 86 4.7 Example radial profile of MGE models . 88 4.8 Deprojected Central Density vs. Inclination . .... 94 4.9 Deprojected density profiles in the z =0plane................. 95 4.10 F547M F814WcolormapofNGC3621 . 98 − 4.11 NCmass-hostgalaxymassrelation . 111 iv 4.12NCsize-NCmassrelation ............................ 112 4.13 NC metallicity vs. host galaxy stellar mass . 113 A.1 χ2 vs.numberofSSPcomponents. 130 A.2 SSPtemplatemismatches ............................ 132 A.3 Errorinmassestimatesvs.SSPage. 134 A.4 SSPdegeneracies ................................. 135 A.5 ResultsoftestsonmockSEDcatalog . 138 A.6 DegeneraciesfromtestsonmockSEDcatalog . 140 v LIST OF TABLES Page 2.1 TheGalaxySample................................ 10 2.2 HST /WFC3FilterProperties&ExposureTimes . 12 3.1 Best-fit surface bightness profile parameters . ...... 31 4.1 ParametersDerivedFromGlobalSEDFits . 73 4.2 Fractional Weights of SSPs in the Fit . 78 4.3 ComparisontoDynamicalMassEstimates . 80 4.4 Definitions of Surface Density Models . 88 4.5 Multi-Gaussian Expansion Models . 90 4.6 AgeRadialProfileSlopes............................. 97 4.7 Comparison of Resolved and Unresolved Mass and Age Estimates . ..... 99 4.8 Comparison With Mass Estimates Derived From MLCRs . 102 4.9 CentralSurfaceDensities. 105 4.10 Old,Metal-PoorFractions . 108 vi ACKNOWLEDGMENTS Support for program GO-12163 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Re- search in Astronomy, Inc., under NASA contract NAS 5-26555. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propul- sion Laboratory, California Institute of Technology, under contract with the National Aero- nautics and Space Administration. I acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr). Some of the text of this dissertation is a reprint of the material as it appears in the Astronom- ical Journal. Permission to use copyrighted material has been granted by the Astronomical Journal. The co-authors listed in this publication directed and supervised research which is the basis for the dissertation. I would like to thank my research collaborators Anil Seth, Mark den Brok, Luis Ho, Jenny Greene, Michele Cappellari, and Nadine Neumayer. I would like to thank my advisor, Aaron Barth, for years of guidance and support, as well the members of the Barth research group past and present, especially Liuyi Pei, Ben Boizelle, Jonelle Walsh, Carol Hood, Daeseong Park, and Vivian U. None of this would have been possible without the love and support of my wonderful family and friends. I am grateful for the encouragement my parents Tom and Judy Carson, my sister Nora Carson, my (soon to be) brother-in-law Jordan David, and my dear friends Paul Mockus, Alex Kirschenbaum, Beverly Tsai, Jay Mata, Jessica Mata, Steve Buchsbaum, Max Weidmann, Calvin Patel, Emon Heidari, and Coral Wheeler. vii CURRICULUM VITAE Daniel J. Carson EDUCATION Doctor of Philosophy in Physics & Astronomy 2016 University of California, Irvine Irvine, CA Master of Science in Physics 2011 University of California, Irvine Irvine, CA Bachelor of Science in Physics, Minor in Mathematics 2010 University of Illinois at Urbana-Champaign Urbana-Champaign, IL RESEARCH EXPERIENCE Graduate Student Researcher 2011–2016 University of California, Irvine Irvine, California Undergraduate Researcher 2009–2010 University of Illinois at Urbana-Champaign Urbana-Champaign, Illinois TEACHING EXPERIENCE Teaching Associate 2015–2016 University of California, Irvine Irvine, CA Tutor, Minority Sciences Program 2014–2015 University of California, Irvine Irvine, CA Teaching Assistant 2010–2011 University of California, Irvine Irvine, CA viii FIRST AUTHOR REFEREED JOURNAL PUBLICATIONS The Structure of Nuclear Star Clusters in Late-type Spi- 2015 ral Galaxies from Hubble Space Telescope/Wide Field Camera 3 Imaging The Astronomical Journal FIRST AUTHOR PAPERS IN PREPARATION The Stellar Populations of Nuclear Star Clusters in 2016 Late-type Spiral Galaxies from Hubble Space Tele- scope/Wide Field Camera 3 Imaging OTHER REFEREED JOURNAL PUBLICATIONS CONTRIBUTED TO Measuring the Mass of the Central Black Hole in the 2015 Bulgeless Galaxy NGC 4395 from Gas Dynamical Mod- eling The Astrophysical Journal Reverberation Mapping of the KEPLER Field AGN 2014 KA1858+4850 The Astrophysical Journal A Search for Optical Variability of Type 2 Quasars in 2014 SDSS Stripe 82 The Astrophysical Journal The Very Young Type Ia Supernova 2012cg: Discovery 2012 and Early-time Follow-up Observations The Astrophysical Journal ix ABSTRACT OF THE DISSERTATION The Structure & Stellar Populations of Nuclear Star Clusters in Late-Type Spiral Galaxies By Daniel J. Carson Doctor of Philosophy in Physics University of California, Irvine, 2016 Professor Aaron Barth, Chair Luminous, compact stellar
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