University of California, San Diego

UNIVERSITY OF CALIFORNIA, SAN DIEGO Physical Conditions in Damped Lyman alpha Systems A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Physics by Regina A. Jorgenson Committee in charge: Arthur M. Wolfe, Chair Kim Greist Michael L. Norman Kevin B. Quest Mark H. Thiemens 2008 Copyright Regina A. Jorgenson, 2008 All rights reserved The dissertation of Regina A. Jorgenson is approved, and it is acceptable in quality and form for publication on microfilm: Chair University of California, San Diego 2008 iii To my parents Maja and Wil For their unconditional love and boundless support, and for inspiring never-ending wonder with the world. iv TABLE OF CONTENTS SignaturePage............................... iii Dedication ................................. iv TableofContents ............................. v ListofFigures ...............................viii ListofTables ............................... xi Acknowledgments . xiii Vita, Publications, and Fields of Study . xv Abstract ..................................xix 1 Introduction ................................ 1 1.1 GalaxyFormationandEvolution . 1 1.2 Physical Conditions in the Milky Way and local Universe . .... 4 1.2.1 MolecularHydrogen . 5 1.2.2 MagneticFields ........................ 7 1.3 QuasarAbsorptionLineSystems . 8 1.3.1 Formation and Detection of Quasar Absorption Line Systems 8 1.3.2 Classes of Absorption Line Systems . 11 1.4 Damped Lyman α Systems ..................... 14 1.4.1 SurveysforDLAs ....................... 16 1.4.2 Physical Conditions in DLAs . 18 2 Radio-Selected Quasar Survey for Damped Lyman α Systems . 20 2.1 Abstract................................ 20 2.2 Introduction ............................. 21 2.3 TheUCSDSample.......................... 24 2.3.1 ObservationsandAnalysis. 25 2.3.2 Damped Lyα systems ..................... 32 2.4 DLAstatistics ............................ 34 2.4.1 ∆z, g(z), and n(z)....................... 34 2.4.2 fHI(N,X) : The H I Frequency Distribution Function . 36 2.4.3 ℓDLA(X) : The Damped Lyα LineDensity . 37 2.4.4 Ωg: The Cosmological Neutral Gas Mass Density . 37 2.5 Results ................................ 38 2.5.1 UCSDSurveyResults . 38 v 2.5.2 CORALSSurveyResults . 39 2.5.3 CombinedResults . 41 2.5.4 EmptyFields.......................... 47 2.6 Analysis&Discussion . 53 2.7 Copyright ............................... 56 3 Understanding Physical Conditions in Damped Lyman α Systems Through Neutral Carbon FineStructure Lines . 57 3.1 Introduction ............................. 57 3.2 DataandMethodology. 62 3.2.1 Curve of Growth Analysis of Component 3 of DLA 0812+32 74 3.3 Applying the C I fine structure technique . 84 3.3.1 TheSteadyStateEquation . 84 3.3.2 SteadyStateSolution . 86 3.3.3 IonizationEquilibrium. 90 3.4 Results ................................ 99 3.4.1 DLA1331+17 .........................102 3.4.2 FJ0812+32, zabs =2.62633...................108 3.4.3 FJ0812+32, zabs =2.06677...................122 3.4.4 Q2231 00 ...........................123 3.4.5 J2340 −00............................126 3.5 Discussion...............................140− 3.5.1 Comparison with C II∗ technique model . 141 3.5.2 Relation to’high-cool’DLApopulation . 151 3.5.3 ComparisonwiththelocalISM . 154 3.6 Conclusions ..............................156 3.7 Appendix 1: Empirical Determination of C I 1560.3092A˚ fjk value .........................158 3.8 Appendix 2: Molecular Hydrogen . 158 3.9 Acknowledgments. .166 4 Bimodality in Damped Lyman α Systems ................167 4.1 Abstract................................167 4.2 Introduction .............................168 4.3 Bimodality of the ℓc Distribution . .170 4.4 Independent Tests for Bimodality . 181 4.4.1 VelocityInterval . .181 4.4.2 Metallicity ...........................184 4.4.3 Dust-to-GasRatio . .186 4.4.4 Si II λ 1526EquivalentWidth . .187 4.4.5 HIColumnDensity . .188 4.5 ModesofHeating ..........................189 vi 4.5.1 Background Heating of ‘Low Cool’DLAs . 190 4.5.2 LocalHeating .........................193 4.6 SummaryofDLAProperties . .199 4.7 Connections to Bimodality in Galaxies . 201 4.7.1 BivariateDistributions. .201 4.7.2 GalaxyFormationModels . .206 4.8 Conclusions ..............................210 4.9 Acknowledgments. .216 4.10Copyright ...............................216 5 An84-µG Magnetic Field in a Galaxy at z =0.692 ..........217 5.1 Introduction .............................217 5.2 TheDetection ............................218 5.2.1 DetectionDetails. .219 5.3 OpticalData .............................221 5.4 Discussion...............................224 5.5 Acknowledgements . .227 5.6 Copyright ...............................227 Bibliography ................................228 vii LIST OF FIGURES Figure1.1: ISMCartoon ......................... 6 Figure1.2: TypicalQuasarSpectrum . 13 Figure 1.3: Examples of Absorbers of Various Column Densities.... 15 Figure 2.1: Voigt profile fits of radio-selected DLAs. .... 35 Figure 2.2: Redshift sensitivity function . ... 40 Figure 2.3: The H I frequency distribution fHI(N,X) for the 26 DLAs ofthecombinedsample. 44 Figure 2.4: ℓDLA(X) versus redshift for the combined sample . 46 Figure 2.5: Ωg ............................... 48 Figure2.6: Emptyfieldimages . 50 Figure 2.7: Potential impact of Empty Fields . 51 Figure 2.8: Cumulative distribution of number of DLAs . ... 52 Figure2.9: Bootstrappingerroranalysis . .. 54 Figure3.1: CIvelocityprofileofDLA1331+17 . 69 Figure 3.2: DLA 1331+17 velocity structure seen in other ions .... 71 Figure 3.3: DLA0812+32CI velocity structure . 72 Figure 3.4: Low ions that trace the C I velocity structure of DLA 0812+32................................ 73 Figure 3.5: Empirically Derived Curve of Growth for the Narrow b Component3ofDLA0812+12 . 75 Figure 3.6: ∆χ2 test of the fitting of the equivalent widths of the narrow CI component (component 3) of DLA 0812+32 . 76 Figure 3.7: DLA 0812+32 zabs=2.06 C I velocity structure . 79 Figure 3.8: Zoom of DLA 0812+32 zabs=2.06 C I velocity structure alongwithotherlowions. 80 Figure 3.9: Spectra of DLA 2231 00 .................. 82 Figure 3.10: J2340 C I velocity profiles− over five C I multiplets ..... 83 Figure 3.11: Excitation of the fine structure level C I∗ and C I∗∗ caused by increasing the strength of the radiation field . 87 Figure3.12: f1 verus f2 for component 1 of DLA 1331+17 . .. 91 Figure 3.13: n(H I) versus temperature for the allowed solutions of DLA 1331+17component1 ........................ 92 CII Figure 3.14: n(H I) versus log( CI ) for the allowed solutions of DLA 1331+17component1 ........................ 94 Figure 3.15: n(H I) versus temperature for the allowed solutions of DLA 1331+17component1 ........................ 95 CII Figure 3.16: Plotting log( CI ) versus n(H I) for a selection of Jν values 97 viii CII Figure 3.17: Log( CI ) versus n(H I) for the entire range of Jν values forDLA1331+17........................... 98 Figure 3.18: Velocity profiles of the low ions and C II∗ for DLA1331+17 105 Figure 3.19: H2 excitation diagrams for the components of DLA 0812+32118 Figure 3.20: Critical densities as a function of temperature for the H2 rotationalJstates. .121 Figure 3.21: H2 excitation diagram for component 3 of DLA 0812+32 −1 with the H2 b value fixed to 0.68 km s to match that of the associatedCI .............................122 Figure 3.22: DLA 0812+32 zabs=2.06 C I velocity structure along with otherlowions .............................124 Figure 3.23: The resulting pressures (2σ) for DLA 0812+32, zabs=2.06 . 125 Figure 3.24: DLA 2340 plot of 7 C I components along with low ions and H2 .................................133 Figure 3.25: DLA 2340 plot of H2 over several J levels . 137 Figure 3.26: The H2 excitation diagrams for the 6 components of DLA 2340 00 that contain H ......................138 − 2 Figure 3.27: Pressure curves and star formation rate solutions for DLA 1331+17................................144 Figure 3.28: DLA 1331+17 2σ range of solutions for range of CII∗ tech- niquesolutiuons. .. .. .. .145 Figure 3.29: DLA 2231 00 2σ range of solutions for range of CII∗ tech- − niquesolutiuons. .. .. .. .147 Figure 3.30: DLA 0812+32 component 1 global 2σ range of solutions for range of CII∗ technique solutiuons . 148 Figure 3.31: DLA 0812+32 component 2 global 2σ range of solutions for range of CII∗ technique solutiuons . 149 Figure 3.32: DLA 0812+32 component 3 global 2σ range of solutions for range of CII∗ technique solutiuons . 150 Figure 3.33: Minimum χ2 fits to representative sample of C I -bearing DLAs .................................155 Figure 3.34: Determination of C I λ1560f-value . .159 Figure 4.1: ℓc versus NHI forthe76sampleDLAs. .176 Figure 4.2: Histogram of 37 positive ℓc detections. .177 Figure 4.3: Histograms comparing positive detections and lower and upperlimits ..............................179 Figure 4.4: Histograms of velocity intervals . .183 Figure4.5: HistogramsofDLAmetallicity. 185 Figure 4.6: HIstograms of DLA dust-to-gas ratio . 186 Figure 4.7: Histograms of Si II λ1526 equivalent width . 188 Figure 4.8: Histograms of H I column density . 189 ix Figure 4.9: Thermal Equilibria Curves . 191 Figure 4.10: Histograms of ΣSFR .....................196 Figure 4.11: Threshold values of ΣSFR versus diameter of smoothing kernel .................................198 Figure 4.12: Bivariate distributions of various parameters versus W1526 . 203 Figure 4.13: Bivariate distributions of various parameters versus ∆v90 . 205 Figure 4.14: Comparison between M/H histograms

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