vlt kinematics for omega centauri : further support for a central bh

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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