Galactic Bulge Feedback and Its Impact on Galaxy Evolution
Total Page：16
File Type：pdf, Size：1020Kb
University of Massachusetts Amherst ScholarWorks@UMass Amherst Open Access Dissertations 9-2009 Galactic Bulge Feedback and its Impact on Galaxy Evolution Shikui Tang University of Massachusetts Amherst, [email protected] Follow this and additional works at: https://scholarworks.umass.edu/open_access_dissertations Part of the Astrophysics and Astronomy Commons Recommended Citation Tang, Shikui, "Galactic Bulge Feedback and its Impact on Galaxy Evolution" (2009). Open Access Dissertations. 130. https://scholarworks.umass.edu/open_access_dissertations/130 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. GALACTIC BULGE FEEDBACK AND ITS IMPACT ON GALAXY EVOLUTION A Dissertation Presented by SHIKUI TANG Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY September 2009 Department of Astronomy c Copyright by Shikui Tang 2009 All Rights Reserved GALACTIC BULGE FEEDBACK AND ITS IMPACT ON GALAXY EVOLUTION A Dissertation Presented by SHIKUI TANG Approved as to style and content by: Q. Daniel Wang, Chair Daniela Calzetti, Member Houjun Mo, Member Monroe Rabin, Member Ronald L. Snell, Department Chair Department of Astronomy To my love. ACKNOWLEDGMENTS First of all, I sincerely thank my advisor, Professor Daniel Wang, for his careful guidance, inexhaustible inculcation, ebullient encouragement, and generous support in the past several years. His enthusiasm and perseverance in science greatly in- spire and encourage me to accomplish this dissertation. I am deeply indebted to his kindness and consideration to help me overcome many hardships in the life. Special thanks go to Prof. John Kwan and Prof. Bill Irvine for their help as the Graduate Program Director. I would also like to thank Professors Daniela Calzetti, Houjun Mo, and Monroe Rabin for serving my Dissertation Committee. Without their support the completion of this dissertation would not have been possible. I am grateful to my collaborators, M. Ryan Joung, Yu Lu, Houjun Mo, and Mordecai-Mark Mac Low, for their insightful comments and prompt feedback on my work. The encouraging and friendly atmosphere in the Astronomy Department always let me feel at home and should be one of the pleasant memories hereafter. Finally, no words can adequately express my appreciation to my family. The software used in this work was in part developed by the DOE-supported ASCI / Alliance Center for Astrophysical Thermonuclear Flashes at the University of Chicago. Computations were performed at Pittsburgh Supercomputing Center supported by the NSF. v ABSTRACT GALACTIC BULGE FEEDBACK AND ITS IMPACT ON GALAXY EVOLUTION SEPTEMBER 2009 SHIKUI TANG B.Sc., BEIJING NORMAL UNIVERSITYA M.Sc., BEIJING NORMAL UNIVERSITY Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Q. Daniel Wang Galactic bulges of early-type spirals and elliptical galaxies comprise primarily old stars, which account for more than half of the total stellar mass in the local Universe. These stars collectively generate a long-lasting feedback via stellar mass loss and Type Ia supernovae. According to the empirical stellar mass loss and supernova rates, the stellar ejecta can be heated to more than 107 K, forming a very hot, diffuse, and iron- rich interstellar medium. Conventionally a strong galactic wind is expected, especially in low- and intermediate-mass early-type galaxies which have a relatively shallow potential well. X-ray observations, however, have revealed that both the temperature and iron abundance of the interstellar medium in such galaxies are unexpectedly low, leading to the so-called “missing feedback” and “missing metal” problems. As an effort to address the above outstanding issues, we have carried out a se- ries of hydrodynamic simulations of galactic bulge feedback on various scales. On vi galactic halo scales, we demonstrate that the feedback from galactic bulges can play an essential role in the halo gas dynamics and the evolution of their host galaxies. We approximately divide the bulge stellar feedback into two phases: 1) a starbusrt- induced blastwave from the formation of the bulge built up through frequent major mergers at high redshifts and 2) a gradual feedback from long-lived low mass stars. The combination of the two can heat the surrounding gas beyond the virial radius and stop further gas accretion, which naturally produces a baryon deficit around Milky Way-like galaxies and explains the lack of large-scale X-ray halos. On galactic bulge scales, we study the collective 3-dimensional effects of super- novae with their blastwaves resolved. We find that the sporadic explosions of super- novae can produce a wealth of substructures in the diffuse hot gas and significantly affect the spectroscopic properties of the X-ray-emitting gas. The differential emis- sion measure in the temperature space has a broad lognormal-like distribution. Such distribution enhances the X-ray emission at both low and high energy bands. We further show that the SN Ia ejecta is not well-mixed with the ambient medium and the X-ray emission is primarily from the shocked stellar wind materials which in general have low metallicities. These 3-dimensional effects provide a promising expla- nation to the above “missing feedback” and “missing metal” problems. In addition, we demonstrate that the supernova iron ejecta forms a very hot bubbles, which have relatively larger radial velocities driven by buoyancy, resulting in a smaller iron mass fraction in the bulk outflow. These distinct properties give a natural explanation to the observed positive iron abundance gradient which has been a puzzle for decades. vii TABLE OF CONTENTS Page ACKNOWLEDGMENTS ............................................. v ABSTRACT ................................................... ....... vi LIST OF TABLES ................................................... xii LIST OF FIGURES..................................................xiii GLOSSARY ................................................... ...... xx CHAPTER 1. INTRODUCTION ................................................. 1 1.1 Galactic Bulge Feedback and Galaxy Evolution . ..............1 1.2 Organization of the Dissertation ..................... ...............5 2. FEEDBACK FROM GALACTIC STELLAR BULGES AND HOT GASEOUS HALOES OF GALAXIES ..................... 9 2.1 Introduction .................................... .................9 2.2 Galaxy Model and Methodology ....................... ............13 2.2.1 The Growth of Dark Matter Halo ...................... .....13 2.2.2 Stellar Bulge Feedbacks . ...........17 2.2.2.1 Starburst feedback ............................ 17 2.2.2.2 Gradual feedback ............................. 19 2.2.3 Methods for Gas Evolution Simulations . .........21 2.3 Results.......................................... ...............23 2.3.1 Dynamical Structures and Evolution . ..........24 2.3.1.1 Reference Model .............................. 24 viii 2.3.1.2 Dependence on the SB feedback efficiency . 26 2.3.1.3 Dependence on the gradual feedback . 29 2.3.1.4 Dependence on the treatment of cooled gas . 31 2.3.2 Baryonic content and X-ray Emission . ......33 2.4 Discussion......................................... .............36 2.4.1 The Over-cooling Problem........................ ..........36 2.4.2 Dynamic state of hot gas........................... ........38 2.4.3 The Missing Stellar Feedback Problem . .......39 2.4.4 Additional Remarks and Caveats . ........41 2.5 Summary......................................... ..............45 3. SUPERNOVA BLAST WAVES IN LOW-DENSITY HOT MEDIA: A MECHANISM FOR SPATIALLY DISTRIBUTED HEATING .................................... 47 3.1 Introduction .................................... ................47 3.2 SimulationSetup ................................. ...............50 3.3 Results: Outer Blastwave Evolution . ............51 3.4 Results: Interior Structure of the Supernova Remnants . ............54 3.5 Discussions ........................................ .............56 4. SCALABILITY OF SUPERNOVA REMNANT SIMULATIONS ............................................... 59 4.1 Introduction .................................... ................59 4.2 ScalingScheme................................... ...............61 4.2.1 BasicIdea...................................... ..........61 4.2.2 Additional Constraints........................... ..........64 4.3 Application Examples.............................. ..............65 4.3.1 Sedov-Taylor Solution.......................... ............65 4.3.2 SNRsinHotGas.................................... ......66 4.3.3 SNR Seed Generation for 3D Simulations . .......67 4.3.4 SN Ejecta and Scalable Initial Condition . ..........69 4.3.5 SNRReverseShock................................. .......71 4.4 Discussion ......................................... ............73 5. TYPE IA SUPERNOVA-DRIVEN GALACTIC BULGE WIND ................................................... ...... 75 ix 5.1 Introduction .................................... ................76 5.2 ModelandMethod.................................. ............79 5.2.1 ModelBasics .................................... .........79 5.2.2 One Dimensional Model............................ ........82 5.2.3 Three Dimensional