Evolution of Galaxies in the Cosmic Web

240 Pages·2015·7.71 MB·English

UC Riverside
UC Riverside Electronic Theses and Dissertations
Title
Evolution of Galaxies in the Cosmic Web
Permalink
https://escholarship.org/uc/item/679334zr
Author
Darvish Sarvestani, Behnam
Publication Date
2015

Peer reviewed|Thesis/dissertation
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University of California
UNIVERSITY OF CALIFORNIA
RIVERSIDE
Evolution of Galaxies in the Cosmic Web
A Dissertation submitted in partial satisfaction
of the requirements for the degree of
Doctor of Philosophy
in
Physics
by
Behnam Darvish Sarvestani
December 2015
Dissertation Committee:
Dr. Bahram Mobasher, Chairperson
Dr. Gabriela Canalizo
Dr. Brian Siana
The Dissertation of Behnam Darvish Sarvestani is approved:
Committee Chairperson
University of California, Riverside
Acknowledgements
I wish to acknowledge everyone who helped me out during my academic career. I would
especially like to thank my parents, brothers, and sisters for their continuous support and
encouragement. I would also like to thank all my teachers and mentors who contributed
greatly to my education and understanding and, more importantly, to be a better human.
Without them, I would not have been able to achieve many of my goals.
My special thanks goes to my supervisor, Professor Bahram Mobasher, who was not
only a superb mentor, but also a great friend. I learned from him how to be a great human
being. I am thankfulto him for providing me with a relaxed environment and a tremendous
degree of freedom so that I could peacefully do my research.
I am very grateful to my friend Dr. David Sobral who significantly helped me during
my studies and had an essential role in making this dissertation possible.
I wish to thank Drs. Gabriela Canalizo and Brian Siana for their tremendous help and
guidance. I thank them for agreeing to be members of my dissertation committee and for
reading my thesis. I additionally wish to thank Dr. Brian Siana for all his hard work to
make our astronomy department a more dynamic and convivial place.
I would like to thank my great friends Hooshang Nayyeri, Shoubaneh Hemmati, Ehsan
Norouzifar,MostafaKhezri,IreneShivaei,AliBeyramzadeh,mysplendidfriendsattheFZX
house, including Michael Beaumier, Christopher Heidt, Patrick Odenthal, Oleg Martynov,
and all my wonderful friends in Riverside with whom I have had joyful moments. I will
always have pleasant memories of them, and I am very grateful for their friendship.
A comprehensive list of people who helped me become the person that I am today is
not feasible. However, I am really grateful to all of them (You know who you are!).
This work is partly based on research that has been either published in the Astrophys-
ical Journal (2014ApJ...796...51D and 2015ApJ...805..121D) or submitted to (manuscript
number: ApJ99672).
iii
To my Parents,
Thanks for your endless love and continuous support
iv
ABSTRACT OF THE DISSERTATION
Evolution of Galaxies in the Cosmic Web
by
Behnam Darvish Sarvestani
Doctor of Philosophy, Graduate Program in Physics
University of California, Riverside, December 2015
Dr. Bahram Mobasher, Chairperson
We study the effects of environment on the evolution of galaxies, with an emphasis on two
different approaches towards the definition of environment: (1) environment defined based
on the local surface density of galaxies and (2) environment defined based on the major
components of the cosmic web; i.e., filaments, clusters and the field. In the first approach,
surface density field is estimated using a variety of estimators and tested with simulations.
Usingtheestimatedsurfacedensitiesassignedtogalaxies,weobserveastrongenvironmental
dependence on the properties of galaxies (e.g., SFR, sSFR and the quiescent fraction) at
z<1. We explore the fractional role of stellar mass and environment in quenching the star-
∼
formation. In the second approach, we use the Multi-scale Morphology Filter algorithm to
disentangle the density field into its component. We apply this method to a sample of star-
forming galaxies for a large-scale structure at z 0.84 in the HiZELS-COSMOS field. We
∼
show that the observed median SFR, stellar mass, sSFR, the mean SFR mass relation and
−
itsscatterforstar-forminggalaxiesdonotstronglydependonthecosmicweb. However,the
fraction of Hα star-forming galaxies varies with environment and is enhanced in filaments.
Furthermore, we study the physical properties of a spectroscopic sample of star-forming
galaxies in a large filament in the COSMOS field at z 0.53, with spectroscopic data taken
∼
v
with the Keck/DEIMOS spectrograph, and compare them with a control sample of field
galaxies. We spectroscopically confirm the presence of a large galaxy filament ( 8 Mpc).
∼
We show that within the uncertainties, the ionization parameter, EW, EW versus sSFR
relation, EW versus stellar mass relation, line-of-sight velocity dispersion, dynamical mass,
and stellar-to-dynamical mass ratio are similar for filament and field star-forming galaxies.
However, we show that on average, filament star-forming galaxies are more metal-enriched
( 0.1 0.15 dex) and the electron densities are significantly lower (a factor of 17) in
∼ − ∼
filament star-forming systems compared to those in the field. Our results highlight the
potential role of galaxy filaments and intermediate-density environments on the evolution
of galaxies, which has been poorly investigated.
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Contents
1 Introduction 1
2 Density Field Estimation and Cosmic Web of Galaxies 6
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Data and Sample Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Determination of the Large Scale Distribution of Galaxies . . . . . . . . . . 11
2.3.1 Redshift Slicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3.2 Photo-z Probability Weights . . . . . . . . . . . . . . . . . . . . . . 14
2.4 Surface Density Estimation: The Methods . . . . . . . . . . . . . . . . . . . 15
2.4.1 Weighted Adaptive Kernel Estimator . . . . . . . . . . . . . . . . . . 15
2.4.2 Weighted k-Nearest Neighbors (k-NN) estimator . . . . . . . . . . . 23
2.4.3 Weighted Voronoi Tessellation Estimator . . . . . . . . . . . . . . . 24
2.4.4 Weighted Delaunay Triangulation Estimator . . . . . . . . . . . . . 25
2.5 Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.5.1 Simulation 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.5.2 Simulation 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.6 Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.7 Cosmic Web Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.8 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3 New Insights into the Evolution of Galaxies with Environment 56
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3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.2 Data and Sample Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.3 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.3.1 SFR and sSFR Evolution with Environment and Galaxy Type . . . 63
3.3.2 Evolution of the Quiescent Fraction with Environment and Stellar Mass 70
3.3.3 Evolution of Rest-frame Color with Environment and Stellar Mass
For Quiescent Galaxies. . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.3.4 EffectoftheEnvironmentontheComovingNumberandMassdensity
of Massive Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
4 Cosmic Web and Star Formation Activity in Galaxies 93
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
4.2 The Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4.2.1 The Star-forming Sample . . . . . . . . . . . . . . . . . . . . . . . . 97
4.2.2 The Control Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.2.3 Mass and SFR Estimation . . . . . . . . . . . . . . . . . . . . . . . . 99
4.2.4 Completeness and Contamination. . . . . . . . . . . . . . . . . . . . 102
4.3 Large Scale Structure Identification . . . . . . . . . . . . . . . . . . . . . . . 104
4.3.1 Local Surface Density . . . . . . . . . . . . . . . . . . . . . . . . . . 104
4.3.2 Filament, Cluster and Field Selection . . . . . . . . . . . . . . . . . 108
4.4 Results and Comparison with Other Studies . . . . . . . . . . . . . . . . . . 109
4.4.1 Fraction of Star-forming Galaxies in the Cosmic Web . . . . . . . . 109
4.4.2 The SFR and Stellar Mass in the Cosmic Web . . . . . . . . . . . . 114
4.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
4.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
5 Spectroscopic Study of Star-forming Galaxies in Filaments and the Field131
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
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5.2 Motivation and the LSS Extraction . . . . . . . . . . . . . . . . . . . . . . . 138
5.3 Spectroscopic Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
5.3.1 Target Selection for Spectroscopy . . . . . . . . . . . . . . . . . . . . 139
5.3.2 Observational Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . 141
5.3.3 Data Reduction and Calibration . . . . . . . . . . . . . . . . . . . . 142
5.3.4 Spectroscopic completeness . . . . . . . . . . . . . . . . . . . . . . . 142
5.3.5 Filament Spectroscopic Confirmation . . . . . . . . . . . . . . . . . . 143
5.4 Selection of Star-forming, Emission-line Galaxies . . . . . . . . . . . . . . . 145
5.4.1 Stellar Mass Estimation . . . . . . . . . . . . . . . . . . . . . . . . . 145
5.4.2 SFR Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
5.4.3 AGN Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
5.4.4 Stacking Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
5.5 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
5.5.1 Electron Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
5.5.2 Metallicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
5.5.3 Ionization Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
5.5.4 Line Equivalent Width . . . . . . . . . . . . . . . . . . . . . . . . . . 163
5.5.5 Velocity Dispersion and Dynamical Mass . . . . . . . . . . . . . . . 169
5.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
5.7 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
6 Summary and Conclusions 181
References 188
Appendix 224
A1 Effect of Density Field Estimation based on Different Sample Selections . . 224
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