Ludwig-Maximilians-Universitat¨ Sigillum Universitatis Ludovici Maximiliani The Kinematics of the Intracluster Light in the Core of the Hydra I Cluster Dissertation der Fakultat¨ fur¨ Physik Dissertation of the Faculty of Physics der Ludwig-Maximilians-Universitat¨ Munchen¨ at the Ludwig Maximilian University of Munich fur¨ den Grad des for the degree of Doctor rerum naturalium vorgelegt von Giulia Ventimiglia presented by aus Catania, Italien from Munchen,¨ 22. Dezember 2010 Sigillum Universitatis Ludovici Maximiliani 1. Gutachter: PD Dr. Ortwin E. Gerhard referee: 2. Gutachter: Prof. Dr. Hans Bohringer¨ referee: Tag der mundlichen¨ Prufung:¨ 18. Februar 2011 Date of the oral exam: To my father Contents Contents iii List of Figures vii List of Tables ix Zusammenfassung xi Abstract xiii 1 Introduction 1 1.1 ClustersofGalaxies..... ..... ...... ..... ...... ... ..... 1 1.1.1 Substructures in clusters of galaxies . ......... 2 1.1.2 Clusters of galaxies: X-ray observations . .......... 3 1.1.3 Clusters of galaxies: optical observations . ........... 5 1.1.4 Mechanisms causing galaxy evolution in clusters . ........... 9 1.2 TheIntraclusterLight. ...... 11 1.2.1 Formation mechanisms and numerical simulations . .......... 12 1.2.2 Amountandmorphology. 13 1.2.3 Metallicity: individual stars as diffuse light tracers . 16 1.2.4 TheICLandtheBCGs............................. 17 1.2.5 Kinematics ................................... 19 1.3 TheThesis....................................... 24 2 The dynamically hot stellar halo around NGC 3311 29 2.1 Introduction.................................... 30 2.2 Observations and archive data . ....... 30 iii 2.3 Datareduction................................... 32 2.4 The kinematics of the NGC 3311 stellar halo . ......... 35 2.5 Conclusions..................................... 37 2.6 Acknowledgements ................................ 37 3 Intracluster Planetary Nebulas in the Hydra I Cluster 39 3.1 Introduction.................................... 39 3.2 Observations .................................... 40 3.2.1 The Multi-Slit Imaging Spectroscopy technique . ........... 40 3.2.2 Observationalsetup . 41 3.3 Datareduction................................... 41 3.4 Selection Criteria for the PN population: the wavelength-magnitude plane . 43 3.5 Conclusions..................................... 45 3.6 Acknowledgements ................................ 45 4 A Ly α survey of background galaxies at z 3.12 47 ∼ 4.1 Introduction.................................... 47 4.2 The Multi-Slit Imaging Spectroscopy technique . ............. 48 4.3 Observationalsetup..... ...... ..... ...... ...... .. ..... 48 4.4 Datareduction................................... 49 4.5 Lyα candidates and their physical characteristics . .......... 49 4.6 Acknowledgements ................................ 51 5 The unmixed kinematics of intracluster stars in the core of the Hydra I cluster 53 5.1 Introduction.................................... 54 5.2 The Hydra I cluster of galaxies (Abell 1060) . ........... 56 5.3 Probing the ICL kinematics using Planetary Nebulas . ............. 57 5.3.1 Planetary Nebulas as kinematical probes and distance indicators . 57 5.3.2 The Multi-Slit Imaging Spectroscopy technique . ........... 58 5.4 Observations .................................... 58 5.5 Data reduction and analysis . ....... 59 5.5.1 Identification of Emission-Line Objects . ......... 59 5.5.2 Photometry ................................... 60 5.6 ThePNsampleinHydraI ............................. 61 5.7 Kinematic substructures and α parameter for the observed PN sample in Hydra I . 64 5.7.1 Predicting the luminosity function and LOSVD with MSIS.......... 64 5.7.2 Reality of observed kinematic substructures . ........... 67 5.7.3 Low α-parameter in the core of Hydra I . 68 5.8 The substructures in the Hydra I cluster core . ............ 71 5.8.1 Spatial distributions of the PN velocity components . ............. 71 5.8.2 Spatial and velocity distribution of Hydra I galaxies .............. 73 5.8.3 Galaxy evolution and presence of substructures in the core of Hydra I . 74 5.9 SummaryandConclusions . 77 5.10 Acknowledgements ..... ..... ...... ..... ...... .... 78 6 Disrupted galaxies in the Hydra I cluster 79 6.1 Introduction.................................... 80 6.2 Optical and Near Infrared imaging of the Hydra I core . ............. 82 6.2.1 V band photometry - Observations and data reduction . ........... 82 6.2.2 Ks band photometry - 2MASS archive data . ..... 83 6.3 Surface photometry for NGC 3311 and NGC 3309 in V and Ks bands ........ 83 6.3.1 Isophotefitting ................................ 83 6.3.2 Analysis of the V, Ks surface profiles . ...... 85 6.3.3 Two-dimensional model for the light distribution in NGC 3311 and NGC 3309 85 6.3.4 Morphology of the light excess in the NE quadrant of NGC 3311 . 89 6.4 Long slit spectroscopy of the NGC 3311 halo . ......... 90 6.5 Correlation among substructures in the diffuse light, PNs and galaxies distributions . 92 6.5.1 Light excess and PNs substructure . ...... 92 6.5.2 Differences in the α parameter ......................... 93 6.5.3 Light excess and substructures in the galaxy distribution ........... 94 6.6 Summaryandconclusions . 96 6.7 Acknowledgements ................................ 97 7 HCC 26: the characteristics of one of the dwarf galaxies in the core of Hydra I 99 7.1 Introduction.................................... 99 7.2 The dwarf galaxies in the core of the Hydra I cluster: photometric characteristics . 100 7.2.1 Observational set up, data reduction and 2D modeling . ........... 100 7.2.2 Results ..................................... 100 7.3 HCC26 ......................................... 101 7.3.1 Kinematics ................................... 101 7.3.2 Ageandmetallicity. ...... ..... ...... ...... ..... 102 7.4 HCC 26: comparison with dwarf galaxy samples in nearby clusters . 103 7.4.1 Lick indices and stellar population parameters . ............ 103 7.4.2 Structural parameters and fundamental plane . .......... 105 7.5 Summaryandconclusions . 107 8 Summary and conclusions 111 Acknowledgments 121 Bibliography 123 List of Figures 1.1 Mihos2005photometry. 15 1.2 ICL in the Centaurus cluster . ...... 16 1.3 Examples of Planetary Nebulas spectra . .......... 20 1.4 MSIS mask for the Hydra I cluster . ...... 24 2.1 Gemini and FORS2 long-slit spectra positions . ............ 31 2.2 Examples of spectra of NGC 3311 along its major axis . ........... 32 2.3 Major axis line-of-sight velocity and velocity dispersion profiles for NGC 3311 . 34 2.4 Properties of the stellar halo of NGC 3311 . .......... 36 3.1 AtypicalMSISPNspectrum . 42 3.2 Velocity-Magnitude plane for the PNs in the Hydra I core . .............. 43 4.1 The Lyα sample..................................... 50 5.1 The physical characteristics of the PN sample . ............ 62 5.2 Cumulative PN luminosity function . ........ 67 5.3 Simulated PN population for NGC 3311 . ....... 68 5.4 Observed and predicted cumulative PN numbers . ........... 71 5.5 PN spatial distribution in the Hydra I cluster . ............. 72 5.6 Velocity distribution of the galaxies in the Hydra I cluster............... 75 5.7 Spatial distribution of the galaxies in the Hydra I cluster................ 76 6.1 Unsharp masked V band image of NGC 3311 . ..... 82 6.2 Isophotes, P.A., ellipticity and average SB profiles in V and Ks bands of NGC 3311 . 84 6.3 Isophote shape parameter profiles in V and Ks band images ofNGC3311 . 84 6.4 V and Ks band average surface brightness profiles of NGC 3311 ........... 86 6.5 Major and minor axis V band folded profiles of NGC 3311 . .......... 87 vii 6.6 Ks band 2D model of NGC 3311 and NGC 3309 . 88 6.7 V band 2D model of NGC 3311 and NGC 3309 . 88 6.8 V and Ks band profiles along major and minor axis of NGC 3311 ........... 89 6.9 Lightexcessspectrum. ..... 91 6.10 Fourier cross-correlation function computed from the light excess spectrum . 92 6.11 PNs on top of the residual V band image of the Hydra I core . ............ 95 6.12 Dwarf galaxies on top of the residual V band image of the Hydra I core . 95 7.1 SpectrumofHCC26 ................................. 102 7.2 LickindicesofHCC26.............................. 104 7.3 Magnitude vs age and magnitude vs metallicity relations forHCC26. 105 7.4 Kormendy relation for HCC 26 . 106 7.5 Position on fundamental plane of HCC 26 . ........ 108 List of Tables 2.1 Measured velocities and velocity dispersions of NGC 3311.............. 38 6.1 V and Ks band photometric parameters for NGC 3311 and NGC 3309 ........ 88 6.2 Positions, V band magnitudes and velocities for the dwarfs in the core of Hydra I . 94 7.1 Photometric characteristics of the DWs in the core of the Hydra I cluster . 100 ix Zusammenfassung Dem aktuellen kosmologischen Modell nach wachsen Galaxienhaufen – die gr¨oßten virialisierten Systeme des Universums – durch die Akkretion kleinerer Objekte aus der umgebenden, wabenartigen kosmischen Massenverteilung. Die entsprechenden Galaxien kommen dabei in Wechselwirkung sowohl mit anderen Galaxien als auch mit dem heißen R¨ontgengas (ICM) und dem Gravitationsfeld des Galaxienhaufens, und ver¨andern in der Folge ihre Struktur. Einige der dabei auftretenden Prozesse sind ’tidal stripping’ (Massenverlust durch Gezeitenkr¨afte), die Verschmelzung mit anderen Galaxien und ’ram pressure stripping’ (Gasverlust durch den Staudruck des R¨ontgengases im Haufen). Diese Prozesse spielen nicht nur f¨ur die weitere Entwicklung der Galaxien eine Rolle, sondern sind auch verantwortlich f¨ur