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Weak Lensing and Modified Gravity of Cosmic Structure University of Pennsylvania ScholarlyCommons Publicly Accessible Penn Dissertations 2014 Weak Lensing and Modified Gravity of Cosmic Structure Joseph Clampitt University of Pennsylvania, [email protected] Follow this and additional works at: https://repository.upenn.edu/edissertations Part of the Astrophysics and Astronomy Commons Recommended Citation Clampitt, Joseph, "Weak Lensing and Modified Gravity of Cosmic Structure" (2014). Publicly Accessible Penn Dissertations. 1240. https://repository.upenn.edu/edissertations/1240 This paper is posted at ScholarlyCommons. https://repository.upenn.edu/edissertations/1240 For more information, please contact [email protected]. Weak Lensing and Modified Gravity of Cosmic Structure Abstract We offer predictions of symmetron modified gravity in the neighborhood of realistic dark matter halos. The predictions for the fifth force (FF) are obtained by solving the nonlinear symmetron equation of motion in the spherical NFW approximation. We compare the three major known screening mechanisms: Vainshtein, Chameleon, and Symmetron around such dark matter sources, emphasizing the significant differences between them and highlighting observational tests which exploit these differences. In addition to halos, we investigate the behavior of the FF in voids in chameleon modified gravity models using the spherical collapse method. The FF can be many times larger than the Newtonian force. This is very different from the case in halos, where the FF is no more than 1/3 of gravity. Individual voids in chameleon models grow larger by ~10%. The number density is up to 2.5 times larger in chameleon models. This difference is about 10 times larger than that in the halo mass function. Turning to weak lensing data analysis, we search for the lensing signal of massive filaments between 220,000 pairs of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey. We use a nulling technique to remove the contribution of the LRG halos, resulting in a 10-sigma detection of the filament lensing signal. We compare the measurements with halo model predictions based on a calculation of 3-point halo-halo-mass correlations. Comparing the "thick" halo model filament to a "thin" string of halos, thick filaments larger than a Mpc in width are clearly preferred by the data. In addition to filaments, dark matter oidsv should exhibit a weak lensing signal. We find oidsv in the galaxy distribution using a novel algorithm, then perform a stacked shear measurement on 20,000 voids with radii between 15-40 Mpc/h and redshifts between 0.16-0.37. We detect the characteristic radial shear signal of voids with a statistical significance that exceeds 13-sigma. The mass profile corresponds to a fractional underdensity of about -0.4 inside the void radius and a slow approach to the mean density. Degree Type Dissertation Degree Name Doctor of Philosophy (PhD) Graduate Group Physics & Astronomy First Advisor Bhuvnesh Jain Subject Categories Astrophysics and Astronomy This dissertation is available at ScholarlyCommons: https://repository.upenn.edu/edissertations/1240 WEAK LENSING AND MODIFIED GRAVITY OF COSMIC STRUCTURE Joseph Clampitt A DISSERTATION in Physics and Astronomy Presented to the Faculties of the University of Pennsylvania in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy 2014 Supervisor of Dissertation Graduate Group Chairperson Bhuvnesh Jain Randall Kamien Professor, Physics and Astronomy Professor, Physics and Astronomy Dissertation Comittee: Gary Bernstein, Professor, Physics and Astronomy Larry Gladney, Professor, Physics and Astronomy Bhuvnesh Jain, Professor, Physics and Astronomy Ravi Sheth, Professor, Physics and Astronomy Justin Khoury, Associate Professor, Physics and Astronomy Acknowledgements I would like to thank my thesis committee, Gary Bernstein, Larry Gladney, Bhuvnesh Jain, Justin Khoury, and Ravi Sheth, for taking the time to review my thesis work. Thanks go also to the Cosmology and Astrophysics Professors who made this an interesting subject to learn: Gary Bernstein, Bhuvnesh Jain, Justin Khoury, Adam Lidz, and Mark Trodden. I’m grateful to my officemates, Melinda Andrews, Alan Meert, and David Moore for answering numerous Python and LaTeX questions. I’m indebted to a number of postdocs at Penn for their mentorship: Anna Cabré, Yan-Chuan Cai, Tim Eifler, Elisabeth Krause, Marcos Lima, and Vinu Vikram. I’d like to thank my collaborators on the projects composing this thesis: Yan-Chuan Cai, Bhuvnesh Jain, Justin Khoury, Baojiu Li, and Masahiro Takada. I would like to thank the National Science Foundation and Department of Energy for the funding that made this research possible. A special thanks goes to Erin Sheldon for the generous use of his shear catalogs, without which the measurements in the second half of this thesis would have been impossible. Special thanks go also to Mike Jarvis for clear, intuitive explanations of many difficult topics. I will always be grateful to Yan-Chuan Cai for his guidance and mentoring, especially in the early stages of graduate school. Finally I’d like to thank my advisor, Bhuvnesh Jain, for a valuable graduate school experience, especially for the freedom to work on interesting projects and the opportunity to travel and be stimulated by conversations with numerous people in the field. ii ABSTRACT WEAK LENSING AND MODIFIED GRAVITY OF COSMIC STRUCTURE Joseph Clampitt Bhuvnesh Jain We offer predictions of symmetron modified gravity in the neighborhood of realistic dark matter halos. The predictions for the fifth force (FF) are obtained by solving the nonlinear symmetron equation of motion in the spherical NFW approximation. We compare the three major known screening mechanisms: Vainshtein, Chameleon, and Symmetron around such dark matter sources, emphasizing the significant differences between them and highlighting observational tests which exploit these differences. In addition to halos, we investigate the behavior of the FF in voids in chameleon modified gravity models using the spherical collapse method. The FF can be many times larger than the Newtonian force. This is very different from the case in halos, where the FF is no more than 1/3 of gravity. Individual voids in chameleon models grow larger by 10%. The number density is up to 2.5 times larger in chameleon models. This difference is about 10 times larger than that in the halo mass function. Turning to weak lensing data analysis, we search for the lensing signal of massive filaments between 220,000 pairs of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey. We use a nulling technique to remove the contribution of the LRG halos, resulting in a 10-sigma detection of the filament lensing signal. We compare the measurements with halo model predictions based on a calculation of 3-point halo-halo-mass correlations. Comparing the "thick" halo model filament to a "thin" string of halos, thick filaments larger than a Mpc in width are clearly preferred by the data. In addition to filaments, dark matter voids should exhibit a weak lensing signal. We find voids in the galaxy distribution using a novel algorithm, then perform a stacked shear measurement on 20,000 voids with radii between 15-40 Mpc/h and redshifts between 0.16-0.37. We detect the characteristic radial shear signal of voids with a statistical significance that exceeds 13- sigma. The mass profile corresponds to a fractional underdensity of about -0.4 inside the void radius and a slow approach to the mean density. iii Contents Title i Acknowledgements ii Abstract iii Contents iv List of Tables ix List of Figures x 1 Introduction 1 1.1 Modified Gravity . .1 1.1.1 How and why does Modified Gravity replace Dark Energy? . .1 1.1.2 Screening of the Fifth Force . .3 1.1.2.1 Symmetron Screening . .4 1.1.2.2 Chameleon Screening . .6 1.1.3 The fifth force in astrophysical environments . .7 1.2 Weak Lensing . 10 1.2.1 Lensing Geometry . 11 1.2.2 Relating true and observed images . 12 iv CONTENTS 1.2.3 Lensing signal of dark matter halos . 15 1.2.4 Statistical and systematic errors . 16 2 Symmetron Gravity in Halos 20 2.1 Introduction . 20 2.2 Force profiles of NFW halos . 22 2.2.1 Symmetron theory . 22 2.2.2 NFW halos . 24 2.3 Results for isolated halos . 27 2.4 Host-satellite effects . 34 2.4.1 Model . 34 2.4.2 Results . 35 2.5 Discussion . 40 3 Void Abundance in MG 43 3.1 Introduction . 43 3.2 The Chameleon Theory . 45 3.2.1 Cosmology with a Coupled Scalar Field . 46 3.2.2 Specification of Model . 48 3.3 Static underdensity solutions . 49 3.3.1 Voids in Newtonian Gravity . 49 3.3.2 Voids in Chameleon Theories . 50 3.3.3 Radial Profile of the Scalar Field . 55 3.3.4 The Fifth Force . 56 3.4 Evolving individual void . 59 3.4.1 Evolution of Environment . 60 3.4.2 Evolution of Underdensity . 61 3.5 Void definition and statistics . 65 v CONTENTS 3.5.1 Excursion Set Theory . 66 3.5.2 First crossing barrier for void . 67 3.5.3 Moving environment approximation . 69 3.5.4 Conditional first-crossing distributions . 71 3.5.4.1 Unconditional First Crossing of a Moving Barrier . 71 3.5.4.2 Conditional First Crossing of a Moving Barrier . 72 3.5.4.3 Results . 73 3.5.5 Environment-averaged first-crossing . 76 3.5.6 Theory Variations . 79 3.6 Discussion . 80 4 Filament Lensing 86 4.1 Introduction . 86 4.2 Measurement Technique . 88 4.2.1 Nulling spherical components . 88 4.2.2 Systematic and halo ellipticity subtraction . 94 4.2.3 Jackknife Realizations . 95 4.3 Data . 96 4.3.1 Pair catalog . 96 4.3.2 Background source catalog . 98 4.4 Theory: Thick- and thin-filament models . 101 4.4.1 Thick-filament from the halo model .
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