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Exploring the Effect of Active Galactic Nuclei on Quenching, Morphological Transformation and Gas Flows with Simulations of Galaxy Evolution

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Exploring the Effect of Active Galactic Nuclei on Quenching, Morphological Transformation and Gas Flows with Simulations of Galaxy Evolution EXPLORING THE EFFECT OF ACTIVE GALACTIC NUCLEI ON QUENCHING, MORPHOLOGICAL TRANSFORMATION AND GAS FLOWS WITH SIMULATIONS OF GALAXY EVOLUTION By RYAN BRENNAN A dissertation submitted to the Graduate School—New Brunswick Rutgers, The State University of New Jersey in partial fulfillment of the requirements for the degree of Doctor of Philosophy Graduate Program in Physics and Astronomy written under the direction of Dr. Rachel Somerville and approved by New Brunswick, New Jersey October, 2017 ABSTRACT OF THE DISSERTATION Exploring the Effect of Active Galactic Nuclei on Quenching, Morphological Transformation and Gas Flows with Simulations of Galaxy Evolution By RYAN BRENNAN Dissertation Director: Dr. Rachel Somerville We study the evolution of simulated galaxies in the presence of feedback from active galactic nuclei (AGN). First, we present a study conducted with a semi-analytic model (SAM) of galaxy formation and evolution that includes prescriptions for bulge growth and AGN feedback due to galaxy mergers and disk instabilities. We find that with this physics included, our model is able to qualitatively reproduce a population of galaxies with the correct star-formation and morpho- logical properties when compared with populations of observed galaxies out to z ∼ 3. We also examine the characteristic histories of galaxies with different star-formation and morphological properties in our model in order to draw conclusions about the histories of observed galaxies. Next, we examine the structural properties of galaxies (morphology, size, surface density) as a ii function of distance from the “star-forming main sequence” (SFMS), the observed correlation between the star formation rates (SFRs) and stellar masses of star-forming galaxies. We find that, for observed galaxies, as we move from galaxies above the SFMS (higher SFRs) to those below it (lower SFRs), there exists a nearly monotonic trend towards more bulge-dominated morphology, smaller radius, lower SFR density, and higher stellar density. We find qualitatively similar results for our model galaxies, again driven by our prescriptions for bulge growth and AGN feedback. Next, we conduct a study of the effect of AGN feedback on the gas in individual galaxies using a suite of cosmological hydrodynamical simulations. We compare two sets of 24 galaxies 12 13.4 with halo masses of 10 - 10 M run with two different feedback models: one which includes stellar feedback via UV heating, stellar winds and supernovae, AGN feedback via momentum- driven winds and X-ray heating, and metal heating via photoelectric heating and cosmic X-ray background heating from accreting black holes in background galaxies (MrAGN), and another model which is identical except that it does not include any AGN feedback (NoAGN). We find that our AGN feedback prescription acts both “ejectively,” removing gas from galaxies in powerful outflows, and “preventatively”, suppressing the inflow of gas onto the galaxy. The histories of MrAGN galaxies are gas ejection-dominated, while the histories of NoAGN galaxies are gas recycling-dominated. This difference in gas cycles results in the quenching of star formation in MrAGN galaxies, while their NoAGN counterparts continue to form stars until z=0. Finally, we examine how this change in the baryon cycle affects the metal content of MrAGN galaxies relative to NoAGN galaxies and find that a combination of gas removal from and metal injection into the hot gas halo results in higher average halo metallicities in MrAGN galaxies. iii Acknowledgments First, I would like to thank my advisor, Rachel Somerville, for all of her support and guidance over the last six years. I would also like to thank my thesis committee (Alyson Brooks, Tad Pryor, Wim Kloet, and Thorsten Naab) for their insightful questions and suggestions. I would like to thank the Rutgers astronomy group: faculty, postdocs and graduate students past and present who have created a great atmosphere in which to work, even when things were difficult. Joel: Thanks for all of the office conversations and Babylon 5. Ena: Thanks for all of your help and never getting annoyed at how many emails I sent you. Sheehan, Jon, Carl, Jesse, Anna and especially Catie: thanks for everything. It was pretty fun most of the time. Thank you to my family, Patrick, Tracy and Daniel, for supporting me even when they weren’t exactly sure what it was I was doing. Portions of this work have appeared or will appear in publication elsewhere. Chapter 3 has been published as Brennan et al. (2015) and Chapter 4 has been published as Brennan et al. (2017). Chapter 5 has been submitted to MNRAS and Chapter 6 will soon be submitted. I would like to thank the CANDELS team for all of their advice and comments on Chapters 3 and 4, and I would like to thank all of my collaborators and co-authors (Viraj Pandya, Guillermo Barro, Ned Taylor, Stijn Wuyts, Eric Bell, Avishai Dekel, Harry Ferguson, Dan McIntosh, Casey Papovich, Joel Primack, Asa Bluck, Sandy Faber, Anton Koekemoer, Peter Kurczynski, Jeffrey Newman, Michaela Hirschmann, Thorsten Naab and Jerry Ostriker). These works have been supported by HST Theory grant HST-AR-13270-A and the Downs- brough Fund, as well as by the Simons Foundation through a Simons Investigator grant to rss. iv Support for HST Programs GO-12060 and GO-12099 was provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. v Dedication For Zorp the Surveyor vi Table of Contents Abstract ............................................. ii Acknowledgments ....................................... iv Dedication ............................................ vi List of Tables .......................................... x List of Figures ......................................... xi 1. Introduction ........................................ 1 1.1. Galaxy Formation . 1 1.2. Star Formation, Chemical Enrichment, and Morphology . 2 1.3. AGN Feedback . 7 1.4. Semi-analytic Models . 12 1.5. Hydrodynamical Simulations . 13 1.6. The Contents of This Thesis . 13 2. Simulations and Observational Data ......................... 17 2.1. Simulations . 17 2.2. Observational Data . 31 vii 3. Quenching and Morphological Transformation in CANDELS and a Semi- analytic Model ......................................... 34 3.1. Introduction . 34 3.2. Results . 40 3.3. Discussion . 56 3.4. Summary and Conclusions . 75 4. The Relationship Between Star-Formation Activity and Galaxy Structural Properties ............................................ 78 4.1. Introduction . 78 4.2. Evolution of Star-forming and Quiescent Galaxies in the SAM . 83 4.3. Distribution of Properties in the Star formation Rate-Stellar Mass Plane . 86 4.4. Distance from the Main Sequence . 97 4.5. Distribution of Distance as a Function of Galaxy Properties . 100 4.6. Discussion . 108 4.7. Summary and Conclusions . 118 5. Momentum-driven Winds from Radiatively Efficient Black Hole Accretion and Their Impact on Galaxies .................................. 121 5.1. Introduction . 121 5.2. Methods . 127 5.3. Results . 128 5.4. Discussion . 157 5.5. Summary . 165 6. The Effect of Mechanical AGN Feedback on Chemical Enrichment ...... 169 viii 6.1. Introduction . 169 6.2. Results . 170 6.3. Discussion . 191 6.4. Conclusions . 192 7. Conclusions ......................................... 194 Appendix A. Conversion from B/T to Sérsic Index in Chapter 3 ......... 198 Appendix B. Results of Chapter 3 Using B/T ..................... 202 Bibliography .......................................... 207 ix List of Tables 3.1. Coefficients for main sequence fit . 43 3.2. Slopes for star formation cut . 43 5.1. Final properties of three example galaxies . 130 x List of Figures 1.1. Local galaxy color bimodality . 4 1.2. Morphology in the SFR-M∗ plane. 7 1.3. The M-σ relation. 10 3.1. sSFR-M∗ distribution of galaxies. 45 3.2. Quiescent fraction of galaxies . 46 3.3. Quiescent fraction divided by mass . 48 3.4. Spheroid-dominated fraction of galaxies . 49 3.5. Spheroid-dominated fraction divided by mass . 50 3.6. Division of galaxies in the sSFR-n plane . 53 3.7. Sérsic index distribution . 54 3.8. sSFR distribution . 54 3.9. Fraction of galaxies in each sSFR-n subpopulation . 57 3.10. Subpopulation fraction with n = 2 cut . 58 3.11. Schematic overview of physical processes . 59 3.12. Fraction of galaxies that have been disturbed . 63 3.13. Evolution of simulated SFD galaxy . 64 3.14. Evolution of simulated QS galaxy . 66 3.15. Evolution of simulated SFS galaxy . 68 3.16. Evolution of simulated QD galaxy . 71 xi 4.1. Evolution of SFR for simulated present day star-forming and quiescent galaxies . 85 4.2. Distribution of galaxies in SFR-M∗ plane . 87 4.3. Distribution of median Sérsic index in SFR-M∗ plane . 90 4.4. Distribution of median Sérsic index in SFR-M∗ plane for noDI model . 91 4.5. Distribution of median effective radius in SFR-M∗ plane . 93 4.6. Distribution of median SFR density in SFR-M∗ plane . 94 4.7. Distribution of median stellar mass density in SFR-M∗ plane . 95 4.8. Distribution of various model properties in SFR-M∗ plane . 96 4.9. Median Sérsic index as a function of distance from the main sequence . 98 4.10. Median effective radius as a function of distance from the main sequence . 99 4.11. Median SFR density as a function of distance from the main sequence . 100 4.12. Median stellar mass density as a function of distance from the main sequence . 101 4.13. Distribution of SFR in galaxy property bins in SAM and Sloan . 103 4.14. Distribution of SFR in galaxy property bins in SAM . 104 4.15. Distribution of SFR in galaxy property bins at low redshift . 106 4.16. Distribution of SFR in galaxy property bins in middle redshift slice . 107 4.17. Distribution of SFR in galaxy property bins at high redshift . 109 5.1. History of galaxy m0163 . 131 5.2. History of galaxy m0329 . 133 5.3.
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