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VLT kinematics for Omega Centauri : Further support for a central BH. E. Noyola et al. 2010, ApJ, 719, L60. 2011 Jun 30 (Thu) Sang Chul KIM ( 김상철 ). BHs – 3 kinds. Stellar mass BHs : M ● ≤ 100 M ⊙ death of massive stars Super massive BHs : M ● ∼ 10 6 – 10 9.5 M ⊙ (SMBHs). - PowerPoint PPT Presentation
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VLT kinematics for Omega Centauri : Further support for a
central BH
E. Noyola et al. 2010, ApJ, 719, L60
2011 Jun 30 (Thu)
Sang Chul KIM ( 김상철 )
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BHs – 3 kindsStellar mass BHs : M● ≤ 100 M⊙ death of massive stars
Super massive BHs : M● ∼ 106 – 109.5 M⊙ (SMBHs)
Intermediate-mass BHs ∼103 M⊙ (IMBHs; 102 - 104 M⊙)
Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)
M●- σ relation
Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)
Tremaine et al. (2002, ApJ, 574, 740)
IMBHs
ω CentauriRA(J2000) = 13 26 46DEC = -47 28 37 (Harris 1996, AJ, 112, 1487)
l = 309.10, b = 14.97E(B-V) = 0.12[Fe/H] = -1.62d = 5.3 kpc 4.8±0.3 kpc (van de Ven+06)
largest GC rt = 69 pcmost massive GC 5.1×106 M⊙
2.5×106 M⊙ (van de Ven+06)
MV = -10.3most flattened GC (ε=1-b/a=0.19)
N
E
MPI/ESO 2.2m/WFI (BVI) ~ 30’×30’
NGC 1978 in LMC
ε= 1-b/a = 0.33
might be the stripped core of a dwarf galaxy
Y.-W. Lee et al. 1999, Nature, 402, 55
ω CentauriMetallicity spread
Double main sequence
Central σ = 22 ±4 km/s (Meylan+95)
Fast global rotation = 8 km/s at r=11 pc (Merritt+97)
Retrograde orbit around the MW (Dinescu+01)
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BH in ωCentauriNoyola et al. (2008)
line-of-sight velocity dispersion (LOSVD) rise toward the center M● = (4±1)×104 M⊙
van der Marel & Anderson (2010)
HST/ACS proper motions
M● = (1.8±0.3)×104 M⊙ for isotropic model
M● ≤ 7.4×103 M⊙ for anisotropic model
※ Center separation ∼12”
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Surface brightness profile of ωCentauri
Noyola et al. (2008, ApJ, 676, 1008) : Fig 1
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Velocity dispersion profile of ωCentauri
Noyola et al. (2008) : Gemini South/GMOS IFU
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ObservationsVLT2/ARGUS IFU with FLAMES, 2009 June 15-16
R ~ 10,400
8200 – 9400 Å region Ca triplet region (8450 – 8700 Å)
FOV = 11.5”×7.3” (0.52”×0.52” pixels)
~12”
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Fig 1
~30”×40”
Noyola+08 new kinematic center
Anderson & van der Marel 2010
Previous GMOS IFU obs
Constructed ARGUS images
~12”
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Hot stars
Exclude regions dominated by
(1) hot stars with Paschen-series lines and
(2) bright stars
~15% of the pixels are excluded
Fig 2 : spectral fit to the integrated spectra
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Dynamical analysis
5 annuli centered on each center
New kinematic center / Noyola et al. (2008) / Anderson & van der Marel (2010)
S/N ≥40 in each bin
Central annulus ∼60 px, outer annulus ∼500 px
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Velocity dispersions
Fig 3 core radius, rc = 1.40’ = 84” (log 84 = 1.92)
New kinematic center / Noyola et al. (2008) / Anderson & van der Marel (2010)
Every case : increase in the dispersion inside the rc
compared to data r > 50” (log 50 = 1.70)
※ thick lines : isotropic models without a BH
Binary fraction ≤ 18% (Carney+ 2005) will cause only a few % increase in σ
7.5×104 M⊙
0 M⊙
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Calculated χ2 values for each model
Noyola et al. (2008) : lowerχ2 values
M ● = (5
.2±0.5)×104 M ⊙
M● = (4.75±0.75)×104 M⊙
M ● =
(3.0
±0.
4)×
104 M
⊙
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Velocity dispersions
σ(100”) ∼ 17 km/s
7.5×104 M⊙
0 M⊙
σ(center) ∼ 22.8 km/s
Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)
prediction : M● = 1.3×104 M⊙
sphere of influence ~ 5”
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Thank you.
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GCs with possible IMBHs
Baumgardt et al. (2005, ApJ, 620, 238)
M80M62
M54
47 Tuc (N104)M10 (N6254)
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BHs in GCs
Safonova & Stalin (2010, NewA, 15, 450)
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Dark stellar remnants
(e.g.) neutron stars, stellar mass BHs, massive WDs
Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)
Dark stellar
remnants
Luminous component