Characterizing Distant Galaxies: Spectral Energy Distribution Analysis of X-ray Selected Star ...

205 Pages·2014·3.54 MB·English

by  Seth Pohatan Johnson

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Open Access Dissertations
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Seth Pohatan Johnson
University of Massachusetts Amherst
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CHARACTERIZING DISTANT GALAXIES:
SPECTRAL ENERGY DISTRIBUTION ANALYSIS OF
X-RAY SELECTED STAR FORMING GALAXIES
A Dissertation Presented
by
SETH P. JOHNSON
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 2013
Department of Astronomy
(cid:13)c Copyright by Seth P. Johnson 2013
All Rights Reserved
CHARACTERIZING DISTANT GALAXIES:
SPECTRAL ENERGY DISTRIBUTION ANALYSIS OF
X-RAY SELECTED STAR FORMING GALAXIES
A Dissertation Presented
by
SETH P. JOHNSON
Approved as to style and content by:
Grant W. Wilson, Chair
Daniel Q. Wang, Member
Alexandra Pope, Member
Carlo Dallapiccola, Member
Stephen Schneider, Department Chair
Department of Astronomy
To my friends and family.
ACKNOWLEDGMENTS
I would like to thank my advisor, Grant Wilson, for everything he has provided
over these many years. His helpful comments and positive attitude have greatly aided
my efforts and encouraged me to strive forward. I am truly indebted to his support.
I would also like to thank Daniel Wang for providing the first support and guid-
ance into my early graduate career. Additionally, I extend my thanks to the UMass
astronomy department and faculty members for the many opportunities and educa-
tional experiences.
I wish to thank the AzTEC team members, present and former, whom I have
worked closely with over the years and learned so much, including Min Yun, David
Hughes, Itziar Aretxaga, James Lowenthal, Kim Scott, Jay Austermann, David
Sanchez, Milagros Zeballos, Yuping Tang.
I want to thank my peers and the friends I have made during my graduate career
who, in addition to professional support, have provided the means to survive the
various stresses associated with graduate life: Stacey Alberts, Ryan Cybulski, Andy
Boyd, Allison Kirkpatrick, Christina Williams, Yiming Li, Buddy, and Daisy.
Lastly, I wish to thank my supportive family who believed in me and helped me
get to where I am today including my aunt Christy Johnson Cribb, mother Sharon
Clark and late father Stephen M. Johnson Jr.
Support for this work was funded in part by the Northeast Alliance Graduate
Education Program (NEAGEP) and National Science Foundation under grant NSF
HRD 0450339 and through the Chandra X-ray Observatory archival research grant
SAO SP1-12003X.
v
ABSTRACT
CHARACTERIZING DISTANT GALAXIES:
SPECTRAL ENERGY DISTRIBUTION ANALYSIS OF
X-RAY SELECTED STAR FORMING GALAXIES
SEPTEMBER 2013
SETH P. JOHNSON
B.A. Physics-Astronomy, UNIVERSITY OF NORTH CAROLINA, CHAPEL HILL
M.Sc., UNIVERSITY OF MASSACHUSETTS, AMHERST
Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST
Directed by: Professor Grant W. Wilson
Comprehensive and robust analysis of galaxies found throughout cosmic time pro-
vides the means to probe the underlying characteristics of our Universe. Coupling
observations and theory, spectral energy distribution (SED) fitting provides a method
to derive the intrinsic properties of distant galaxies which then aid in defining galaxy
populations and constraining current galaxy formation and evolution scenarios. One
such population are the sub-millimeter galaxies (SMGs) whose high infrared lumi-
nosities – typically associated with dust-obscured star formation – and redshift dis-
tribution places them as likely key components in galaxy evolution. To fully analyze
these systems, however, requires a near complete sampling of the full SED, detailed
models that encapsulate the variety of physical processes and sophisticated methods
vi
for comparing the data and models. In this dissertation, we present the general pro-
pose, Monte Carlo Markov Chain (MCMC) based SED fitting routine SED Analysis
Through Markov Chains (SATMC) and the insight we have gained in modeling a
sample of AzTEC 1.1mm-detected SMGs. The MCMC engine and Bayesian formal-
ism used in the construction of SATMC offers a unique view at the constraints on
model parameter space that are often grossly simplified in traditional SED fitting
methods. We first present the motivation behind SATMC and its MCMC algorithm.
We also highlight a series of test cases that verify not only its reliability but its versa-
tility to various astrophysical applications, including the field of photometric redshift
estimation. We then present the AzTEC SMG sample and preliminary results ob-
tained through counterpart identification, X-ray spectral modeling and SED fitting
with SATMC. Finally, we present the latest work in detailed SED analysis of SMGs
and how these results influence our understanding of the SMG population.
vii
TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ............................................. v
ABSTRACT.......................................................... vi
LIST OF TABLES .................................................... xi
LIST OF FIGURES..................................................xiii
CHAPTER
1. INTRODUCTION ................................................. 1
2. SATMC: SPECTRAL ENERGY DISTRIBUTION ANALYSIS
THROUGH MARKOV CHAINS .............................. 13
2.1 Introduction ....................................................13
2.2 SATMC: The MCMC Algorithm...................................15
2.2.1 MCMC Acceptance and Convergence ........................16
2.2.2 Parallel Tempering ........................................18
2.3 SATMC SED Specific Features ....................................20
2.3.1 Observations and Upper Limits .............................21
2.3.2 Photometric Redshift Estimation ............................23
2.3.3 Template Libraries and SED Synthesis Routines...............24
2.3.4 Inclusion of Priors.........................................25
2.3.5 Application of the Posterior ................................25
2.4 Testing of the MCMC Algorithm ..................................26
2.5 Summary.......................................................32
3. SPECTRAL ENERGY DISTRIBUTION FITTING AS A
PHOTOMETRIC REDSHIFT INDICATOR ................... 33
viii
3.1 Introduction ....................................................33
3.2 CANDELS Data and SED Fitting Tests ............................35
3.2.1 ACS z-band Selected Catalog ...............................36
3.2.2 WFC3 H-band Selected Catalog.............................36
3.2.3 UDS Catalog .............................................37
3.3 Estimating Photo-z with SATMC ..................................37
3.4 CANDELS Photo-z Results .......................................39
3.5 Improving the Photo-z ...........................................41
3.5.1 Model Parametrization and Likelihood Surface ................46
3.5.2 Zero-point Corrections, Luminosity Priors and Emission
Lines .................................................51
3.6 Summary.......................................................59
4. X-RAY DETECTIONS OF SUB-MILLIMETER GALAXIES:
ACTIVE GALACTIC NUCLEI VERSUS STARBURST
CONTRIBUTION ............................................. 62
4.1 Introduction ....................................................62
4.2 Observations and Data Processing .................................66
4.2.1 AzTEC: 1.1 mm Observations ..............................66
4.2.2 Chandra Observations .....................................67
4.2.3 Counterpart Candidates....................................71
4.2.3.1 Chandra Counterparts .............................71
4.2.3.2 Multi-wavelength Counterparts .....................74
4.3 Analysis........................................................76
4.3.1 X-ray Spectral Modeling ...................................76
4.3.1.1 Model A: Absorbed Power-Law .....................77
4.3.1.2 Model B: Absorbed HMXB.........................78
4.3.1.3 Application of X-ray Spectral Models ................80
4.3.2 NIR-to-Radio SED Modeling ...............................83
4.3.2.1 SED Models and Fitting ...........................84
4.3.2.2 SED Fitting Results ...............................86
4.4 Discussion ......................................................97
4.4.1 Origin of 1.1 mm Emission .................................98
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