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X-Ray Spectroscopy of Clusters of Galaxies and of the Cosmic Web

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X-Ray Spectroscopy of Clusters of Galaxies and of the Cosmic Web X-ray spectroscopy of clusters of galaxies and of the cosmic web Norbert Werner May 13, 2008 Cover image: Pair of clusters of galaxies Abell 222 and Abell 223 connected by a cosmic web filament permeated by hot X-ray emitting gas. Image obtained by the XMM- Newton X-ray observatory. The image with the spiders symbolizing clusters of galax- ies as dense nodes on the cosmic web was designed by G´abor Szentp´etery and Aurora Simionescu. c 2008 Norbert Werner All rights reserved. X-ray spectroscopy of clusters of galaxies and of the cosmic web R¨ontgen spectroscopie van clusters van melkwegstelsels en van het kosmische web (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof. dr. J.C. Stoof, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op dinsdag 13 mei 2008 des middags te 2.30 uur door Norbert Werner geboren op 12 maart 1981, te Rozˇnavaˇ (Slowakije) promotor : Prof. dr. F.W.M. Verbunt co-promotor : Dr. J.S. Kaastra Contents 1 Introduction 1 1.1 Chemical enrichment . ......................... 3 1.2 Clusters in the context of the cosmic web .................. 4 2 XMM-Newton Spectroscopy of the Cluster of Galaxies 2A 0335+096 7 2.1Introduction................................... 8 2.2Observationsanddatareduction....................... 9 2.2.1 EPIC analysis . ......................... 9 2.2.2 RGS analysis . ......................... 12 2.3Spectralmodels................................. 12 2.4Globalspectrum................................. 13 2.4.1 EPIC . ................................ 13 2.4.2 RGS . ................................ 16 2.5 Radial profiles.................................. 18 2.5.1 Projected spectra . ......................... 19 2.5.2 Deprojected spectra . ......................... 21 2.5.3 RGS radial profiles........................... 21 2.6 Temperature and iron abundance maps . .................. 23 2.7 Properties of the core on smaller scales . .................. 24 2.8 Abundances and enrichment by supernova types Ia, II, and Population IIIstars...................................... 25 2.9Discussion.................................... 29 2.9.1 Intrinsic temperature structure . .................. 32 2.9.2 Abundance distribution . .................. 33 2.9.3 Possible merger scenario . .................. 34 2.9.4 Relative enrichment by supernova types Ia/II and Population III stars................................... 36 2.10 Conclusions . ................................ 37 2.11 Appendix: The influence of the background subtraction on radial pro- files........................................ 39 3 XMM-Newton high-resolution spectroscopy reveals the chemical evolution of M 87 45 3.1Introduction................................... 46 3.2Observationsanddatareduction....................... 47 ii CONTENTS 3.3Spectralmodels................................. 48 3.3.1 The AGN spectrum . ......................... 49 3.4Results...................................... 51 3.4.1 The combined dataset ......................... 51 3.4.2 Intrinsic absorption or resonant scattering . ....... 53 3.4.3 Radial profiles.............................. 53 3.5Discussion.................................... 57 3.5.1 Chemical enrichment by type Ia and core collapse supernovae . 57 3.5.2 Carbon and nitrogen abundances and enrichment by AGB stars . 58 3.5.3 Spatial abundance distribution . .................. 60 3.6Conclusions................................... 60 4 Observations of metals in the intra-cluster medium 63 4.1Introduction................................... 64 4.2Sourcesofmetals................................ 64 4.3 Abundance studies before XMM-Newton and Chandra .......... 69 4.4 The possibilities and limitations of elemental abundance determinations 71 4.4.1 Spectral modelling and the most common biases . ....... 71 4.4.2 Possibilities and limitations of current instruments . ....... 74 4.5 Spatial distribution of elements . .................. 77 4.5.1 Radial abundance profiles....................... 77 4.5.2 2D distribution of metals . .................. 80 4.6 Element ratios and their reconstruction with supernova models . 80 4.6.1 Results on reconstructed supernova models . ....... 82 4.6.2 Summary of the efforts of using ICM abundances to constrain supernovamodels........................... 84 4.7 Abundances as function of cluster mass and redshift . ....... 85 4.8FutureofICMabundancestudies....................... 88 5 Complex X-ray morphology of Abell 3128: A distant cluster behind a disturbed cluster 91 5.1Introduction................................... 92 5.2 Observations and data analysis . .................. 93 5.2.1 XMM-Newton data . ......................... 93 5.2.2 Background modeling ......................... 94 5.2.3 The X-ray images . ......................... 96 5.3Results...................................... 96 5.3.1 Properties of the X-ray peaks . .................. 96 5.3.2 Optical observation of the background cluster . ....... 101 5.3.3 2D maps of thermodynamic properties . .............. 103 5.4Discussion.................................... 107 5.4.1 The background cluster associated with the NE X-ray peak . 107 5.4.2 The nature of the SW surface brightness peak . ....... 108 5.4.3 The diffuse ICM . ......................... 110 5.5Conclusions................................... 111 CONTENTS iii 6TheOVII X-ray forest toward Markarian 421: Consistency between XMM- Newton and Chandra 113 6.1Introduction................................... 114 6.2 Observations and data analysis . .................. 116 6.2.1 Analysis of the LETGS spectra . .................. 116 6.2.2 Analysis of the RGS spectra . .................. 120 6.2.3 Determing equivalent widths . .................. 121 6.2.4 A note on systematic wavelength errors . .............. 122 6.3Discussion.................................... 123 6.3.1 Significance of the absorption components detected by Chandra . 123 6.3.2 Association of the z = 0.011 component with a Lyα absorber. 128 6.3.3 The final argument: no lines in the RGS spectrum . ....... 129 6.3.4 The 22.02 A˚ feature . ......................... 129 6.4Conclusions................................... 130 7 Possible non-thermal nature of the soft-excess emission in the cluster of galax- ies S´ersic 159-03 131 7.1Introduction................................... 132 7.2 Observations and data analysis . .................. 133 7.2.1 Suzaku data . ......................... 133 7.2.2 XMM-Newton data . ......................... 136 7.2.3 Spectral analysis . ......................... 136 7.2.4 Modeling of the X-ray background emission . ....... 136 7.3Results...................................... 138 7.3.1 Thermal and non-thermal models of soft excess emission . 138 7.3.2 Comparison with XMM-Newton soft excess detections and the systematic uncertainties . .................. 141 7.3.3 Radial distribution of the soft emission . .............. 143 7.3.4 2D maps of the soft excess emission . .............. 145 7.3.5 Search for line emission from the warm gas with RGS ....... 147 7.4Discussion.................................... 148 7.4.1 Presence of the soft excess . .................. 148 7.4.2 Thermal or non-thermal origin? . .................. 148 7.5Conclusions................................... 151 7.6 Appendix: The contamination layer on Suzaku XIS1 . ....... 151 7.6.1 Data reduction . ......................... 152 7.6.2 Simultaneous Suzaku XIS1 and XMM-Newton EPIC/pn obser- vation.................................. 152 7.6.3 Simultaneous XIS1 and Chandra LETGS/HRC observation . 153 8 Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223 155 8.1Introduction................................... 156 8.2 Observations and data analysis . .................. 157 8.2.1 Image analysis . ......................... 158 iv CONTENTS 8.2.2 Spectral analysis . ......................... 158 8.3Results...................................... 159 8.3.1 Imaging . ................................ 159 8.3.2 Spectroscopy . ......................... 160 8.4Discussion.................................... 161 9 Summary 165 9.1 Chemical enrichment of the intra-cluster medium . ....... 165 9.2 Evolution of clusters of galaxies in the context of the cosmic web . 166 10 Nederlandse Samenvatting 169 10.1 Chemische evolutie van het intra-cluster medium . ....... 169 10.2 Evolutie van clusters van melkwegstelsels en het kosmische web . 170 References 173 Curriculum Vitae 181 Thank you 183 Chapter 1 Introduction Clusters of galaxies were initially discovered as overdensities of galaxies on optical plates. They contain hundreds of galaxies within a radius of 1–2 Mpc (Abell 1958), thus they are the most densely populated regions in the Universe. However, the velocity dispersion of the galaxies revealed that the underlying gravitational potential of the clusters is much deeper than that produced only by the total mass of the individual galaxies, unveiling the existence of dark matter (Zwicky 1937). The nature of the dark matter is still unknown, but there are indications that it is cold and collisionless. Its distribution in clusters with redshifts of z 0.1 can be directly mapped using the gravitational distortion of the images of distant background galaxies - a phenomenon known as gravitational lensing. The total mass of galaxy clusters is typically ∼ (1– 20)×1014 M, but the stellar mass within galaxies constitutes only about 1–3% of the total mass. So clearly the most massive
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