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The Evolution of and Starburst-AGN Connection in Luminous and Ultraluminous Infrared Galaxies and Their Link to Globular Cluster Formation

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The Evolution of and Starburst-AGN Connection in Luminous and Ultraluminous Infrared Galaxies and Their Link to Globular Cluster Formation City University of New York (CUNY) CUNY Academic Works All Dissertations, Theses, and Capstone Projects Dissertations, Theses, and Capstone Projects 6-2014 The Evolution of and Starburst-AGN Connection in Luminous and Ultraluminous Infrared Galaxies and their Link to Globular Cluster Formation Stephanie L. Fiorenza Graduate Center, City University of New York How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/gc_etds/206 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] THE EVOLUTION OF AND STARBURST- AGN CONNECTION IN LUMINOUS AND ULTRALUMINOUS INFRARED GALAXIES AND THEIR LINK TO GLOBULAR CLUSTER FORMATION by Stephanie Lynn Fiorenza A dissertation submitted to the Graduate Faculty in Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy, The City University of New York 2014 i © 2014 Stephanie Lynn Fiorenza All Rights Reserved ii This manuscript has been read and accepted for the Graduate Faculty in Physics in satisfaction of the dissertation requirement for the degree of Doctor of Philosophy. Dr. Charles T. Liu __________ _____________________ Date Chair of Examining Committee Dr. Steven G. Greenbaum ______________ ____________________________ Date Executive Officer Dr. Alfred Levine Dr. Matthew O’Dowd Dr. Emily Rice Dr. Sivarani Thirupathi ________________________________________________ Supervisory Committee THE CITY UNIVERSITY OF NEW YORK iii Abstract THE EVOLUTION OF AND STARBURST- AGN CONNECTION IN LUMINOUS AND ULTRALUMINOUS INFRARED GALAXIES AND THEIR LINK TO GLOBULAR CLUSTER FORMATION BY STEPHANIE LYNN FIORENZA Advisor: Dr. Charles T. Liu The evolutionary connection between nuclear starbursts and active galactic nuclei (AGN) in 11 12 luminous infrared galaxies (LIRGs; 10 o<oLIRo< 10 L) and ultraluminous infrared galaxies 12 13 (ULIRGs; 10 < LIR < 10 L), which result from galaxy interactions and mergers and produce the bulk of their radiation as infrared (IR) emission, is not well understood. To this effort, I first 11 13 spectroscopically examine U/LIRGs (10 < LIR < 10 L⊙) within the IRAS 2 Jansky Redshift Survey with 0.05 < z < 0.16. Using new spectrophotometric data, I classify the primary source of IR radiation as being a nuclear starburst or a type of AGN by using the Baldwin-Phillips-Terlevich (BPT) diagrams. I iv show that for the U/LIRGs in my sample the properties that describe their nuclear starbursts and AGN (e.g. star formation rate (SFR), L[O III], optical D parameter, D4000, and EW(Hδ)) are independent of one another, ensuring that no biases affect correlations between these properties and objects' locations on the BPT diagrams. I then derive evolutionary paths on the BPT diagram involving [N II]/Hα that are based on how these properties vary between two U/LIRGs positioned at the end-points. The paths involve U/LIRGs that decrease in SFR and increase in AGN activity. Paths with U/LIRGs that evolve into high luminosity AGN likely do so due to recent, strong starbursts. Second, to study how the properties of the IR power sources in U/LIRGs vary, I use a combination of photometric data points that I carefully measure (using photometry from SDSS, 2MASS, WISE, and Spitzer) and that I retrieve from catalogues (IRAS, AKARI, and ISO) to perform UV to FIR SED-fitting with CIGALE (Code Investigating GALaxy Emission) for 34 U/LIRGs from the IRAS 2 Jy Redshift Survey with 0.01 < z < 0.16. CIGALE allows for the estimation of numerous physical properties by means of a Bayesian-like analysis, but for this work I focus on derived outputs for the SFR, AGN contribution, D4000, stellar mass (Mstar), young stellar population age (i.e. the age of the most recent starburst activity), starburst mass fraction, luminosity absorbed by dust, and stellar mass-weighted age. Comparing the properties of the IR power sources in U/LIRGs with age-related properties provides clues as to which type of IR power source forms first and how starburst age varies with starburst/AGN strength. I find evidence that the nuclear starburst forms first in U/LIRGs, and also find that U/LIRGs with relatively similar SFRs show increased AGN activity if they are older. However, I also find that a young U/LIRG can show a relatively large amount of AGN activity if a very large starburst is present. Then, I quantify the timescales at which the starburst activity in my v U/LIRGs evolves with the use of the Tukey-Kramer method of statistical analysis, and fit an exponential curve to the data to describe the expected amount of decrease in SFR seen for a U/LIRG in my sample over a given change in starburst age. Finally, I find evidence that the stellar mass and starburst mass fractions influence whether a U/LIRG in my sample will have a strong AGN and SFR, respectively. I compare the SFR-Mstar relationship seen in my sample with those predicted by models and found from previous observations. I find that the U/LIRGs with older starbursts (>125 Myr) agree with previous results, while those with younger starbursts show a large dispersion in Mstar. I conclude that this is supporting evidence that the star formation histories and timescales at which the IR power sources in U/LIRGs evolve are responsible for the scatter found for the SFR-Mstar relationship. U/LIRGs that form from merging gas-rich disk galaxies could also represent a stage of galaxy evolution involving heavy formation of globular clusters (GCs). It has been suggested that a large number of stellar clusters form during the merging of two gas-rich disk galaxies, leading to open and young massive clusters with the latter likely evolving into GCs. Furthering our understanding of GC formation can uncover the connection between GCs and their host galaxies, which could, at some point during their formation or evolution, be U/LIRGs. To understand GC formation in the context of hierarchical galaxy formation, it is necessary to understand the origin of their abundance patterns. To this effort, I use SDSS spectra from Data Release 8 and 9 to estimate carbon (C) abundances for five GCs by matching synthetic spectra, created with TURBOSPECTRUM using atmospheric parameters derived from the Segue Stellar Parameter Pipeline, with observed spectra at the CH G-band feature. I find large spreads in the C abundances throughout the color magnitude diagrams of the GCs, which serves as evidence for multiple stellar populations, in contrast to standard models of GC formation. vi Acknowledgements I would like to thank my parents, Todd and Donna, for always being there for me, and for always believing that I could do anything I wanted. You both gave me more than I could have ever imagined of both the stuff that money can buy and the things in life that are even harder to find. I want to thank my brother, Mike, for helping me with computer glitches and discussing programming in Python with me – and you know you always have fun doing it! I want to thank my sister, Mallory, for her encouraging words over the years. I also would like to thank my entire extended family for their encouragement, and give a special thank you to Randy Fiorenza, my Godfather and uncle, for all of the financial and moral support he has given me over the years. Without your generosity my life would be very different. I would like to thank all of the research advisors that I have had the pleasure of working with: Dr. Charles Liu, my thesis advisor, Dr. Tsutomu Takeuchi of Nagoya University in Japan, and Dr. Sivarani Thirupathi of the Indian Institute for Astrophysics in Bangalore, India. I also want to thank Dr. Timothy Beers for giving me an opportunity to continue the work I began in India at the National Optical Astronomy Observatory in Tucson, AZ. I also wish to thank Dr. Kasia Malek of Nagoya University for the many useful comments and scientific discussions. I am also appreciative of the members of my thesis committee for taking the time to read my dissertation and prepare thoughtful questions for my defense: my thesis advisor, Dr. Charles Liu, as well as Dr. Alfred Levine, Dr. Matthew O’Dowd, Dr. Emily Rice, and Dr. Sivarani Thirupathi. Finally, I would like to thank everyone who believed in me, but also all of those who did not. It has been fun proving you wrong! vii Table of Contents Chapter 1: Introduction to Luminous and Ultraluminous Infrared Galaxies ................... 1 1.1 What are Luminous and Ultraluminous Infrared Galaxies? ...................................................... 2 1.2 Overview of Luminous and Ultraluminous Infrared Galaxies ................................................... 4 1.2.1 Discovery ................................................................................................................................................................ 4 1.2.2 Interactions and Merging in U/LIRGs ......................................................................................................... 6 1.2.3 Nuclear Starbursts and AGN as Nuclear Power Sources in U/LIRGs ............................................ 8 1.2.4 Understanding the Starburst-AGN Connection in U/LIRGs ........................................................... 10 Chapter 2: Evolutionary Paths along the BPT Diagram for Luminous and Ultraluminous Infrared Galaxies ................................................................................................... 15 2.1 Abstract ......................................................................................................................................................
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