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0 Luminous Compact Blue Galaxies Graduate Theses, Dissertations, and Problem Reports 2015 Evolution of z ~ 0 Luminous Compact Blue Galaxies Katherine Rabidoux Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Rabidoux, Katherine, "Evolution of z ~ 0 Luminous Compact Blue Galaxies" (2015). Graduate Theses, Dissertations, and Problem Reports. 6464. https://researchrepository.wvu.edu/etd/6464 This Dissertation is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you must obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Dissertation has been accepted for inclusion in WVU Graduate Theses, Dissertations, and Problem Reports collection by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. Evolution of z 0 Luminous Compact Blue Galaxies ∼ Katie Rabidoux Dissertation submitted to the Eberly College of Arts and Sciences at West Virginia University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics Dr. D.J. Pisano, Ph.D., Chair Dr. Loren Anderson, Ph.D. Dr. Amy Keesee, Ph.D. Dr. Dave Frayer, Ph.D. Dr. Yu Gu, Ph.D. Department of Physics and Astronomy Morgantown, West Virginia 2015 Keywords: galaxies: evolution; galaxies: kinematics and dynamics; galaxies: star formation; radio continuum: galaxies; radio lines: galaxies; infrared: galaxies Copyright 2015 Katie Rabidoux ABSTRACT Evolution of z 0 Luminous Compact Blue Galaxies ∼ Katie Rabidoux Luminous compact blue galaxies (LCBGs) are bright (MB 18.5), blue (B 9 ≤ − − V 0.6), massive (M∗ 10 M⊙) star-forming galaxies with high B-band surface brightnesses≤ (SBe(B) ∼21.0) that were common at z 1 when the Universe was ≤ ∼ half of its current age, but are rare in the local Universe. In this thesis, I have conducted studies of the atomic neutral hydrogen (H I) and global star formation properties of a group of the rare z 0 analogs to the common z 1 LCBGs to better understand how this class of galaxies∼ evolves. I have first conduct∼ ed a pilot study of the global star-formation properties of a heterogeneous group of local star-forming galaxies using observations at 33 GHz with the Green Bank Telescope. In this study, we made the first detections at 33 GHz for 22 of the 27 galaxies we observed. We fit spectral energy distributions (SEDs) to the galaxies’ radio continuum emission from 1 GHz 40 GHz and quantified the relative contributions of thermal free-free emission∼ from− massive, short-lived stars and non-thermal synchrotron emission from supernovae. We found that these galaxies followed the radio-far-infrared correlation at 33 GHz, and that the thermal fraction at 33 GHz, spectral index from 1.4 GHz to 33 GHz, and ratio of radio continuum emission at 33 GHz to total far-infrared emission together give an estimate of the relative ages of the most recent episodes of star formation in these galaxies. In the second study, we analyzed resolved H I observations of nine z 0 LCBGs. We found that the LCBGs have a variety of H I morphologies, are∼ rotationally-supported at all radii, and are unlikely to be forming large S0-type bulges. We also found that the disks of LCBGs are stable on average with respect to gravitational instabilities, but may have the potential to form instabilities at large radii. In addition, the LCBGs in our sample had the lowest ratios of ordered rotation to disordered motions in the centers of their disks, supporting the idea of these galaxies forming a small central bulge or bar. Finally, we applied the techniques we used in our study of the global star-formation properties of a heterogenous sample of galaxies to investigate a sample of 42 local (D < 80 Mpc) LCBGs. We found that LCBGs all have evidence of ongoing star formation, though the ages of their most recent episodes of star formation are varied. We also saw that LCBGs without star-forming clumps appeared to have relatively young star formation ages (. 30 Myr), while clumpy LCBGs could have a range of ages, from very young to 100 Myr or more. We conclude that there are likely to be at least two broad causes∼ of star formation in LCBGs, and that their evolutionary paths are likely to be diverse. Acknowledgments First, I would like to thank my parents, Mark and Karen, my sister, Liz, and my husband, Brian Marsteller, for their love and support. My parents have nurtured my interest in astronomy ever since I came home from first grade wanting to learn everything about the solar system, and I will forever be grateful for their enthusiasm. Liz admirably tolerated growing up with such a nerdy sister. Brian has been a wonderful and patient source of support, especially these last few months while I have been finishing my thesis. I am truly fortunate to have such a great family. I would also like to thank my advisor, D.J. Pisano. He has been supportive of me since the first day I walked into his office, and has given me so many opportunities to do interesting science. Thank you for your patience, encouragement, and for pushing me to be a better astronomer. I could not have asked for a better advisor. Finally, I would like to thank everybody who has encouraged me on my path to becoming an astronomer. To Ms. Ardis Herrold, who is the heart and soul of the Radio Astronomy Team at Grosse Pointe North High School, thank you for being welcoming to all students, and for showing me how to do astronomy as a career path. Your mentorship during my time as a RAT gave me the confidence to be a scientist. To Dr. Horace Smith, my undergraduate advisor at Michigan State, thank you for taking me to the campus observatory as often as possible, for your commitment to undergraduate research, and for your support while I was finding my way as an undergraduate. To the astronomy graduate students I knew at MSU and my classmates and friends at WVU, thank you for your kindness, your encouragement, and for always making me feel like I belonged in the department. To my officemates, Spencer Wolfe and Andrew Seymour, thank you for the support, the laughter, and for teaching me how to be a West Virginian. iii Table of Contents List of Tables vii List of Figures ix 1 Introduction 1 1.1 The evolution of galaxies since z 2 .................. 1 1.2 Usefulderivations.............................∼ 6 1.2.1 Gravitational instabilities in star-forming galaxies . 6 1.2.2 From observables to physical properties of star-forming galaxies 9 1.2.2.1 Star formation rates from thermal radio continuum emission......................... 10 1.2.2.2 Star formation rates from nonthermal synchrotron ra- dio continuum emission . 14 1.2.2.3 Far-infrared dust blackbody emission . 16 1.3 Organizationofthethesis ........................ 20 2 Radio continuum observations of local star-forming galaxies using the Caltech Continuum Backend on the Green Bank Telescope 24 2.1 Introduction................................ 25 2.2 Data.................................... 28 2.2.1 Sample Selection . 28 2.2.2 ObservationsandDataReduction . 30 2.3 ResultsandDiscussion .......................... 36 2.3.1 Fluxes ............................... 36 2.3.2 Spectral energy distribution fitting . 36 2.3.2.1 Galaxies with steep radio spectra . 40 2.3.3 Thermalfractions......................... 44 2.3.3.1 Implications for star formation timescales . 44 2.3.4 O stars producing ionizing photons . 47 2.3.5 Supernovarates.......................... 48 2.3.6 Starformationrates ....................... 48 2.3.7 Radio-far-infrared correlation . 50 2.3.7.1 Implications for star formation timescales . 56 2.4 Conclusions ................................ 60 3 Resolved H I observations of local analogs to z 1 luminous compact blue galaxies: evidence for rotation-supported disks∼ 84 3.1 Introduction................................ 85 3.1.1 LCBGs: Analogs to z 1star-forminggalaxies . 85 3.1.2 Goals................................∼ 88 3.2 Sample Selection, Observations, and Data Reduction . 91 3.2.1 Sample selection . 91 3.2.2 GMRTobservationsandreduction . 93 iv 3.2.3 VLAobservationandreductionofMrk325. 94 3.3 Results................................... 105 3.3.1 H I intensity maps, linewidths, and masses . 105 3.3.2 Companions,mergers,andinteractions . 107 3.3.3 Velocitymeasurements . 109 3.3.3.1 Velocities from a slice along the major axis . 110 3.3.3.2 Rotation curve fitting . 110 3.3.4 Comparison with single-dish results . 116 3.3.4.1 Comparison with stellar masses . 122 3.3.5 Tully-Fisher relation . 123 3.3.6 Velocity dispersions . 127 3.3.6.1 Building bulges . 131 3.3.7 Comparison with higher-redshift galaxies . 139 3.4 Conclusions ................................ 140 4 Global star formation properties of local luminous compact blue galaxies 161 4.1 Introduction................................ 162 4.2 SampleSelection ............................. 168 4.3 Observations, Data Reduction, and Flux Measurements . 169 4.3.1 Radiocontinuum ......................... 169 4.3.2 Farinfrared ............................ 173 4.4 SEDFitting................................ 179 4.4.1 Radiocontinuum ......................... 179 4.4.2 Other considerations for radio continuum SED fitting . 183 4.4.2.1 Galaxies with fewer than five observed fluxes . 185 4.4.3 Starformationrates . .. .. 186 4.4.4 Far-infraredSEDs. .. .. 188 4.4.5 Infraredstarformationrates. 191 4.5 Discussion: Star formation properties of LCBGs . 197 4.5.1 Radio-FIR correlation . 197 4.5.1.1 Galaxies off the radio-FIR correlation . 201 4.5.2 Clumpy star formation in the disk .
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