Early-type stellar systems in nearby galaxy clusters [Elektronische Ressource] : from dwarf galaxies to star clusters / Ingo Misgeld. Betreuer: Ralf Bender

Ingo Misgeld

Sujets

• Astronomie

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2011
• Nombre de lectures: 7
• Langue: English
• Poids de l'ouvrage: 9 Mo

Extrait

Early-type stellar systems
in nearby galaxy clusters:
from dwarf galaxies to star clusters
Ingo Misgeld
Mu¨nchen 2011fu¨r GuadalupeEarly-type stellar systems
in nearby galaxy clusters:
from dwarf galaxies to star clusters
Ingo Misgeld
Dissertation
an der Fakult¨at fu¨r Physik
der Ludwig–Maximilians–Universit¨at
Mu¨nchen
vorgelegt von
Ingo Misgeld
aus Essen
Mu¨nchen, den 19.04.2011Erstgutachter: Prof. Dr. Ralf Bender
Zweitgutachter: Priv. Doz. Dr. Markus Kissler-Patig
Tag der mu¨ndlichen Pru¨fung: 08.06.2011Contents
Zusammenfassung xi
1 Introduction 1
1.1 A Universe of dwarf galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 The faint end of the galaxy luminosity function . . . . . . . . . . . 2
1.1.2 Photometric scaling relations of early-type galaxies . . . . . . . . . 4
1.1.3 Surface brightness profiles of early-type galaxies . . . . . . . . . . . 5
1.2 Ultra-compact dwarf galaxies (UCDs) . . . . . . . . . . . . . . . . . . . . . 7
2 The early-type dwarf galaxy population of the Hydra I cluster 11
2.1 Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.1 Observations and selection of candidates . . . . . . . . . . . . . . . 12
2.1.2 Data reduction and radial velocity measurements . . . . . . . . . . 13
2.2 Photometry of early-type dwarf galaxies . . . . . . . . . . . . . . . . . . . 14
2.2.1 Observations and selection of dE/dSph candidates . . . . . . . . . . 14
2.2.2 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.1 Properties of confirmed cluster galaxies . . . . . . . . . . . . . . . . 18
2.3.2 The colour–magnitude relation of early-type galaxies . . . . . . . . 19
2.3.3 The magnitude–surface brightness relation . . . . . . . . . . . . . . 22
2.3.4 The faint end of the galaxy luminosity function . . . . . . . . . . . 24
2.4 Follow-up spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.1 Observations and data reduction . . . . . . . . . . . . . . . . . . . 29
2.4.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.5 Summary and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.5.1 The Hydra I galaxy luminosity function . . . . . . . . . . . . . . . 33
3 A search for UCDs in the Hydra I galaxy cluster 37
3.1 Observations and candidate selection . . . . . . . . . . . . . . . . . . . . . 38
3.1.1 The UCD survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.1.2 The GC survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2 Data reduction and radial velocity measurements . . . . . . . . . . . . . . 41
3.2.1 Systematic radial velocity shifts . . . . . . . . . . . . . . . . . . . . 42vi Contents
3.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.3.1 Photometric and structural properties . . . . . . . . . . . . . . . . 46
VLT/VIMOS imaging . . . . . . . . . . . . . . . . . . . . . . . . . 46
HST/WFPC2 imaging . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.3.2 Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Mean radial velocities . . . . . . . . . . . . . . . . . . . . . . . . . 54
Velocity dispersions . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.4 Discussion and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 The early-type dwarf galaxy population of the Centaurus cluster 63
4.1 Observations and sample selection . . . . . . . . . . . . . . . . . . . . . . . 64
4.1.1 Photometric analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.2 Global photometric and structural parameters . . . . . . . . . . . . . . . . 67
4.2.1 Fundamental scaling relations . . . . . . . . . . . . . . . . . . . . . 67
4.2.2 The dwarf galaxy luminosity function . . . . . . . . . . . . . . . . . 71
4.2.3 Structural parameters from S´ersic fits . . . . . . . . . . . . . . . . . 75
4.2.4 Galaxy sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.2.5 Compact elliptical galaxy candidates . . . . . . . . . . . . . . . . . 77
4.3 Follow-up spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.4 Summary and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.4.1 The faint end of the galaxy luminosity function . . . . . . . . . . . 81
4.4.2 The dependency of effective radius on luminosity . . . . . . . . . . 84
5 Families of dynamically hot stellar systems 87
5.1 Sample description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.1.1 Stellar mass estimates . . . . . . . . . . . . . . . . . . . . . . . . . 89
5.2 Scaling relations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.2.1 Galaxies as distance indicators . . . . . . . . . . . . . . . . . . . . . 94
5.2.2 The sizes of hot stellar systems . . . . . . . . . . . . . . . . . . . . 98
5.2.3 Galaxies and their star cluster mates . . . . . . . . . . . . . . . . . 100
5.2.4 Zone of avoidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
5.2.5 Internal accelerations . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.3 Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6 Summary and outlook 109
6.1 Future prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
A Tables 113
Danksagung 129List of Figures
1.1 Luminosity functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 S´ersic surface brightness profiles . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Ultra-compact dwarf galaxies . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 DSS image of the Hydra I core region . . . . . . . . . . . . . . . . . . . . . 13
2.2 Colour–magnitude diagram of all objects observed with LDSS2 . . . . . . . 14
2.3 Thumbnail images of Hydra I cluster dwarf galaxy candidates . . . . . . . 15
2.4 Map of VLT/FORS1 fields in Hydra I . . . . . . . . . . . . . . . . . . . . . 16
2.5 Radial velocity distribution of objects measured with LDSS2 . . . . . . . . 17
2.6 Properties of all successfully observed LDSS2 objects . . . . . . . . . . . . 18
2.7 Colour–magnitude diagram of early-type galaxies in the Hydra I cluster . . 20
2.8 Magnitude–surface brightness relation of Hydra I dwarf galaxies . . . . . . 21
2.9 S´ersic parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.10 Parameter space of simulated dwarf galaxies . . . . . . . . . . . . . . . . . 24
2.11 SExtractor output-parameters of the artificial galaxies . . . . . . . . . . . . 25
2.12 Hydra I completeness functions . . . . . . . . . . . . . . . . . . . . . . . . 26
2.13 Luminosity function of the Hydra I dwarf galaxies . . . . . . . . . . . . . . 27
2.14 Map of VIMOS pointings for spectroscopic follow-up in Hydra I . . . . . . 28
2.15 Spectra of new, faint dwarf galaxies . . . . . . . . . . . . . . . . . . . . . . 29
2.16 Hydra I galaxy radial velocity distribution . . . . . . . . . . . . . . . . . . 30
2.17 Photometric properties of the newly confirmed Hydra I dwarf galaxies . . . 32
3.1 Map of the surveyed area in the Hydra I cluster . . . . . . . . . . . . . . . 39
3.2 Selection of the UCD candidates . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3 Comparison of radial velocities . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.4 Comparison of UCD and GC velocities . . . . . . . . . . . . . . . . . . . . 43
3.5 Radial velocity histogram . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.6 GC colour-magnitude diagram from GMOS imaging . . . . . . . . . . . . . 45
3.7 Spatial distribution of all observed objects . . . . . . . . . . . . . . . . . . 46
3.8 GC/UCD colour-magnitude diagram from VIMOS pre-imaging . . . . . . . 47
3.9 Colour distribution of confirmed Hydra I GCs/UCDs . . . . . . . . . . . . 48
3.10 Colour-magnitude diagram of all WFPC2 sources . . . . . . . . . . . . . . 49
3.11 Half-light radii and luminosities of the GCs/UCDs with HST imaging . . . 50viii List of Figures
3.12 Residual images for the three brightest UCDs with HST imaging . . . . . . 52
3.13 Magnitudes and velocities as a function of radial distance . . . . . . . . . . 54
3.14 Radial velocity distribution of all identified GCs/UCDs . . . . . . . . . . . 56
3.15 Velocity dispersion as a function of dividing magnitude . . . . . . . . . . . 58
3.16 Radial velocity as a function of azimuthal position . . . . . . . . . . . . . . 59
3.17 Colour composite image of the core of NGC 3311 . . . . . . . . . . . . . . 60
4.1 DSS image of the Centaurus core region . . . . . . . . . . . . . . . . . . . 64
4.2 Map of VLT/FORS1 fields in Centaurus . . . . . . . . . . . . . . . . . . . 65
4.3 Thumbnail images of Centaurus cluster dwarf galaxy candidates . . . . . . 66
4.4 Colour–magnitude diagram of early-type galaxies in the Centaurus cluster 68
4.5 Magnitude-surface brightness relation of Centaurus dwarf galaxies . . . . . 70
4.6 SExtractor analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.7 Centaurus completeness functions . . . . . . . . . . . . . . . . . . . . . . . 72