Intermediate Mass Black Holes in Star Clusters [Elektronische Ressource] : The Case of Omega Centauri (NGC 5139) / Behrang Jalali. Betreuer: Markus Kissler-Patig

Jalali, Behrang

Sujets

• Physik

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2011
• Nombre de lectures: 11
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Intermediate Mass Black Holes
in Star Clusters:
The Case of ω Centauri (NGC 5139)
Behrang Jalali
Munchen¨ 2011Intermediate Mass Black Holes
in Star Clusters:
The Case of ω Centauri (NGC 5139)
Behrang Jalali
Dissertation
an der Fakult¨at fur¨ Physik
der Ludwig–Maximilians–Universit¨at
Munc¨ hen
vorgelegt von
Behrang Jalali
aus Teheran, Iran
Munc¨ hen, den 3 August 2011Erstgutachter: Dr. Markus Kissler-Patig
Zweitgutachter: Prof. Dr. Barbara Ercolano
Tag der mundlic¨ hen Prufung:¨ 28 September 2011To Ati, for everything we sharedviContents
Abstract xiii
Zusammenfassung xiv
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Relationship of IMBHs with Formation and Evolution of Galaxies . . . . . 2
1.2.1 Main IMBH Formation Scenarios . . . . . . . . . . . . . . . . . . . 4
1.2.2 More on the Importance of IMBHs . . . . . . . . . . . . . . . . . . 8
1.3 Detection Methods of IMBHs in Star Clusters . . . . . . . . . . . . . . . . 9
1.4 Omega Centauri (NGC 5139) . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.5 Outline of the thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.5.1 New Central Kinematics for ω Centauri (Chapter 2) . . . . . . . . . 18
1.5.2 Direct N-body Simulations of ω Centauri 3) . . . . . . . . 19
1.5.3 Orbit-based Models (Chapter 4) . . . . . . . . . . . . . . . . . . . . 19
1.5.4 Conclusions and Outlook (Chapter 5) . . . . . . . . . . . . . . . . . 19
2 New Central Kinematics for ω Centauri 21
2.1 Light: Surface Brightness Profile with space and ground-based telescopes . 21
2.2 Kinematics: using HST and VLT-FLAMES telescopes . . . . . . . . . . . . 25
2.2.1 Proper motions: HST data . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.2 Radial velocities: IFU data from VLT-FLAMES . . . . . . . . . . . 28
2.3 Observations and Data Reduction . . . . . . . . . . . . . . . . . . . . . . . 29
2.4 Kinematic Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.5 Isotropic Models and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 37
3 Direct N-body Simulations of ω Centauri 39
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.2 Observational Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.2.1 The Center of ω Centauri . . . . . . . . . . . . . . . . . . . . . . . 43
3.2.2 Surface Brightness Data . . . . . . . . . . . . . . . . . . . . . . . . 43
3.2.3 Kinematical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.3 N-body modelling Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 45viii content
3.3.1 Model Density Profile . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.3.2 Model Kinematic Profile . . . . . . . . . . . . . . . . . . . . . . . . 50
3.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.4.1 No-IMBH Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.4.2 IMBH Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.5 Discussion and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4 Orbit-based Models 67
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.3 Dynamical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.4 Results for ω Centauri from line-of-sight velocities . . . . . . . . . . . . . . 75
4.4.1 IMBH mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.4.2 Anisotropy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.5 Summary and Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5 Conclusions and Outlook 85
5.1 Evidence for a central IMBH in ω Centauri . . . . . . . . . . . . . . . . . . 85
5.2 The VLT-FLAMES kinematic survey of Galactic globular clusters . . . . . 86
Acknowledgements 99List of Figures
1.1 Black hole mass vs. velocity dispersion correlation for galaxies . . . . . . . 3
1.2 A diagram for formation scenario of IMBHs . . . . . . . . . . . . . . . . . 6
1.3 A for of SMBHs . . . . . . . . . . . . . . . . . 7
1.4 A HST image of ω Centauri . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.5 Characteristic phase-space density of stellar systems versus total mass . . . 13
1.6 Projected mass density of stellar systems in terms of total mass . . . . . . 14
1.7 Absolute V-band magnitude vs. cluster half-light radius . . . . . . . . . . . 16
1.8 Color-magnitude diagram of ω Centauri . . . . . . . . . . . . . . . . . . . 17
2.1 Observed V-band surface brightness profile of ω Centauri . . . . . . . . . . 23
2.2 Central field of ω Centauri . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3 Color-magnitude diagram for stars with proper motion measurements . . . 26
2.4 Observed proper motion dispersion profile of ω Centauri . . . . . . . . . . 27
2.5 VLT-FLAMES pointing map of ω Centauri . . . . . . . . . . . . . . . . . . 30
2.6 Spectra of normal stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.7 Spectra of hot and binary stars . . . . . . . . . . . . . . . . . . . . . . . . 32
2.8 Example of integrated spectra for the central bin . . . . . . . . . . . . . . 34
2.9 Model velocity dispersion profile of ω Centauri . . . . . . . . . . . . . . . . 35
22.10 χ values as a function of IMBH mass for the Jeans isotropic models . . . . 36
3.1 Radial velocity dispersion profiles with the same initial log(c). . . . . . . . 48
3.2 velocity disp with the same r . . . . . . . . . 49hp
3.3 Surface brightness profile for a model without an IMBH . . . . . . . . . . . 52
3.4 Radial velocity dispersion profile for a model without an IMBH . . . . . . 53
3.5 Proper motion disp for a model an . . . . . . . 54
3.6 RV dispersion profile for models with different IMBH masses . . . . . . . . 55
3.7 SB profile for models with different IMBH masses . . . . . . . . . . . . . . 56
23.8 χ map for the best-fit IMBH mass . . . . . . . . . . . . . . . . . . . . . . 58
23.9 Reduced combined χ map for the best-fit model IMBH mass . . . . . . . 59
3.10 Surface brightness profile for an IMBH model . . . . . . . . . . . . . . . . 60
3.11 Radial velocity dispersion profile for an IMBH model . . . . . . . . . . . . 61
3.12 Proper motion disp for an model . . . . . . . . . . . . 62
3.13 Stellar M/L profile for the best-fit models . . . . . . . . . . . . . . . . . . 63x
4.1 Internal light profile for ω Centauri . . . . . . . . . . . . . . . . . . . . . . 70
4.2 A schematic diagram for the orbit-based superposition method . . . . . . . 72
24.3 χ contours in terms of IMBH mass and stellar M/L . . . . . . . . . . . . 73
24.4 Marginalized χ values vs. different IMBH masses . . . . . . . . . . . . . . 74
4.5 σ /σ profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76r t
4.6 Projected LOSVDs at several radii . . . . . . . . . . . . . . . . . . . . . . 83
5.1 Low mass end of M versus σ correlation . . . . . . . . . . . . . . . . . . 87BH
5.2 Observed surface brightness profile of two globular clusters in our sample . 89
5.3 Observing strategy for the two observed targets . . . . . . . . . . . . . . . 90