Paleocosmology: Observational Constraints on the Evolution of Galaxies and Large-Scale Structure by Eric James Gaidos Submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctorate of Philosophy at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY May 1996 @ Massachusetts Institute of Technology 1996. All rights reserved. 0 Author. Department of Physics May 23, 1996 Certified by. Claude R. Canizares Professor Thesis Supervisor Accepted by ... -ASSACHUSETTS INSTHU OF TECHNOLOGY JUN 0 5 1996 Paleocosmology: Observational Constraints on the Evolution of Galaxies and Large-Scale Structure by Eric James Gaidos Submitted to the Department of Physics on May 23, 1996, in partial fulfillment of the requirements for the degree of Doctorate of Philosophy ABSTRACT The study of galaxies and their clustering is important to understanding their forma- tion and evolution but also to place constraints on cosmological models. I present two surveys and their analyses: The first is an optical CCD imaging survey of 67 Abell clusters to determine the distribution of luminosities and morphologies of the con- stituent galaxies. A composite luminosity function constructed from the photometric data is well described by a Schechter function with a faint-end slope a = 1.09 + 0.08 and characteristic absolute magnitude Mý = -21.13 ± 0.11 + 5 log h. A systematic brightening of M* with higher cluster redshift and/or cluster density is observed. The data suggests an excess over the best-fit Schechter LF at MR > -16.5. The form of the LF found here is in good agreement with field surveys but conflicts with recent claims for a steep LF in clusters. My photometry of Brightest Cluster Galaxies finds a dispersion of 0.06 magnitudes about a secular trend with redshift. The luminosity evolution is more consistent with models with a flat IMF (giant dominated), but a larger photometric sample is needed to substantiate this. I distinguish between disk and spheroidal galaxies using the moments of the surface brightness profiles and esti- mate the fraction of disk galaxies. The mean fraction is approximately 30% and shows a significant increase in clusters with z > 0.2, consistent with the Butcher-Oemler effect. The second survey is an on-going search for X-ray emitting galaxy clusters in archival Einstein IPC images that includes a multi-aperture source detection routine. An algorithm is developed to quantify the certainty of source extent and select X-ray cluster candidates. The surface density of bright X-ray clusters on the sky is consis- tent with results from the Rosat All Sky Survey, although the numbers involved are very small. I ]present an analysis of CCD imaging follow-up to an X-ray source that appears to be a cluster at a redshift of about 0.3. Thesis Supervisor: Claude R. Canizares Title: Professor ACKNOWLEDGMENTS I wish to express my sincere thanks to Prof. Claude Canizares, my Thesis Committee Chairman, as well as Prof. John Huchra and Prof. Samir Mathur for their assistance as well as patience in the completion of this thesis. Profs. Charles Steidel and John Tonry provided invaluable advice throughout the course of the project. Thanks go to Prof. Paul S!chechter who was daring enough to give a young engineer a crack at astronomy five years ago. The MDM Observatory Time Allocation Committee was very generous in its allotment of telescope time to this thesis project. This project also benefited enormously from the many software packages and databases maintained on the Internet and the many kind people who assisted me in using them. Finally, a most heart-felt thank you to family and friends who supported me both emotionally and intellectually on the long and winding road to a Ph.D; this thesis is dedicated to you. "...And whether you perceive it or not, no doubt the Universe is unfolding as it should..." - Max Ehrmann, Desiderata (.•' f7 O&areA5p--AK Contents 1 Galaxies: The Most Ancient of Fossils 12 1.1 Luminosities & Morphologies as Artifacts ... .............. 15 1.2 ...A nd as Tools .. ....... ...... ...... ...... 18 1.3 Techniques & Previous Research . .................. 19 1.3.1 Luminosities . ...... ......... ........ .. 19 1.3.2 M orphologies .......... ......... ........ 25 1.4 Motivation for this Thesis ........................ 26 2 A Wide-Field Optical Survey of Cluster Galaxies 28 2.1 Description of the Survey and Galaxy Catalog . ............ 29 2.1.1 Cluster selection ......................... 29 2.1.2 Observations ........ .. .. ..... .......... 32 2.1.3 Image Processing .................. ...... 32 2.1.4 Photom etry ....... .. .. .. .. ......... .... 35 2.1.5 Im age Reduction ......................... 37 2.1.6 M agnitude Errors ........................ 43 2.1.7 Com pleteness ........................... 43 2.2 Field Galaxy Counts ........................... 45 2.3 Global Galaxy Cluster Properties . .................. 51 2.3.1 Cluster Richness ......................... 51 2.3.2 M orphology ............................ 55 2.4 Luminosity Functions .......................... 58 2.4.1 LF Construction ......................... 58 2.4.2 Composite Luminosity Function .. .. ... .. ... .. 61 2.4.3 Variation of the Cluster Luminosity Function 2.4.4 Discussion .................. 2.5 Brightest Cluster Galaxies ...... ...... .. 2.5.1 The M1 - M* Differential .... ..... 2.5.2 Discussion ... ..... ........... 2.6 Morphology of Cluster Galaxies .... .... ... 2.6.1 The Technique ................ 2.6.2 Application to the Data .. ..... .... 3 Galaxy Clustering: The Cosmic Rosetta Stone? 100 3.1 Background .................... 100 3.2 Galaxy Cluster Surveys ......... .... 102 3.3 X-ray Clusters ................... 104 3.3.1 X-ray Emission from Clusters .. .... 104 3.3.2 X-ray Cluster Surveys ... ... .... 108 3.4 Limitations of X-ray Surveys . .... .... 111 4 An Archival EINSTEIN IPC X-ray Cluster Surve•y 114 4.1 The Source Catalog . .. ... ... o. o. o o 115 4.1.1 Einstein IPC .......... ... .e . .rt 115 4.1.2 Source Detection ........ 115 4.1.3 Source Identification ...... 117 4.1.4 Source Extent Test ....... 118 4.1.5 The EMSS Survey Revisited .. 123 4.2 Optical Counterparts ......... 124 ........ ° 4.2.1 Digitize Sky Survey Imaging .. 124 Counterparts 4.2.2 CCD Imaging of Galaxy Cluster 124 4.3 X-ray Cluster Candidates .. ..... .. o. .. 129 4.3.1 Bright Sources ...... ... .o . o. o. 129 4.4 Sources with PE > 0.99 .... ..... 129 5 Look-Back Time 143 5.1 A Picture-Puzzle of Galaxies and Clusters . .............. 143 5.2 Lessons Learned from My Field Work . ................. 146 5.3 Looking Forwards ............................. 147 A Eine Kleine Theory: Galaxy Formation 149 B Cluster Luminosity Functions 158 B.1 Photometric Luminosity Functions . .................. 158 B.2 Non-Photometric Luminosity Functions ........... ...... 162 List of Figures 1 Field and Cluster LF - Schechter parameters .... ....... Survey redshifts and filters ..................... *.. 76 CPE reiection criteria and magnitude errors . .... .... ... 76 Field galaxy counts .................. .. ... ... 77 Effects of Galactic extinction ............. ... ... .. 78 Effect of seeing and detection filter width .. .... .. .. .. .. 78 Average star counts and background model parameter covariance . 79 Cluster luminosity overdensity . ...... ..... .. .. .. 80 Cluster luminosity overdensity and peak index . .. .. .. 80 Concentration index vs. peak index .. .... ... ... ... .. 81 Composite luminosity function . .... .... ... .. .. .. .. 82 Error covariance and LF from outer galaxies .. ... .. .. 83 Schechter LF parameter for clusters .. ... ... .. .. ... 83 M* dependence on cluster morphology . ... .. .. .. .. .. 84 M* dependence on cluster overdensity . .... ... .. .. 85 BCG magnitudes .................... .. .. .. .. 86 Distibution of BCG and non-BCG clusters ... ... .. .. .. .. 87 M1- M* vs. M1- M2 ............ .. .. ..... 88 M, - M* vs. cluster morphology indices . .. ... .. .. .. .. 89 M, vs. cluster morphologies .............. .. .. .. .. 90 Hubble Atlas of galaxy morphologies by Q parameter ... ... .. 91 Image degradation for test of Q parameter ... ... ... ... 92 Test of Q parameter with image degradation Fraction of disk galaxies vs. redshift ... Fraction of disk galaxies vs. cluster morphology Fraction of disk galaxies vs. morphology indices IPC Source Counts ........... ................. 131 X-ray Source Identification ...... ................ 132 Flux ratios of point sources ...... ................ 133 Signal-to-noise ratios of point sources .. .......... .... 134 Signal-to-noise ratios of Abell clusters .......... ...... 135 Extent Probability & EMSS Recovery ........ ........ 136 EMSS/Archival IPC comparison . .. ................. 136 X-ray Extent of EMSS Clusters .... ................. 137 POSS E images of Abell Clusters . .. ................. 138 UK Schmidt J Images of Abell Clusters ............... 139 Gunn Filters and Elliptical Colors . .. ...... ........... 140 CCD Photometry Tests ........ ................. 140 13 EX0806.3+2057 Imaging ........ 141 List of Tables 1 Abell Cluster Galaxy Survey .............. .. ..... 96 2 Cluster Morphology Indices ..................... .. 97 3 Cluster Morphology Indices (cont.) . .................. 98 4 Background Fields ............................ 99 5 Variation of LF with Redshift & Cluster Properties . ......... 99 1 Point sources with PE > 0.99 ...................... 132 2 Unidentified Extended X-ray Sources . ................. 142 Chapter 1 Galaxies: The Most Ancient of Fossils The discipline of