1 VLT kinematics for Omega Centauri : Further support for a central BH E. Noyola et al. 2010, ApJ, 719, L Jun 30 (Thu) Sang Chul KIM ( 김상철 )

2 BHs – 3 kinds Stellar mass BHs : M ● ≤ 100 M ⊙  death of massive stars Super massive BHs : M ● ∼ 10 6 – M ⊙ (SMBHs) Intermediate-mass BHs ∼ 10 3 M ⊙ (IMBHs; 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 Centauri RA(J2000) = DEC = (Harris 1996, AJ, 112, 1487) l = , b = E(B-V) = 0.12 [Fe/H] = d = 5.3 kpc 4.8 ± 0.3 kpc (van de Ven+06) largest GC r t = 69 pc most massive GC 5.1 × 10 6 M ⊙ 2.5 × 10 6 M ⊙ (van de Ven+06) M V = most 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 Centauri Metallicity 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)

8 BH in ωCentauri Noyola et al. (2008) line-of-sight velocity dispersion (LOSVD) rise toward the center  M ● = (4 ± 1) × 10 4 M ⊙ van der Marel & Anderson (2010) HST/ACS proper motions  M ● = (1.8 ± 0.3) × 10 4 M ⊙ for isotropic model  M ● ≤ 7.4 × 10 3 M ⊙ for anisotropic model ※ Center separation ∼ 12”

9 Surface brightness profile of ωCentauri Noyola et al. (2008, ApJ, 676, 1008) : Fig 1

10 Velocity dispersion profile of ωCentauri Noyola et al. (2008) : Gemini South/GMOS IFU

11 Observations VLT2/ARGUS IFU with FLAMES, 2009 June R ~ 10, – 9400 Å r egion  Ca triplet region (8450 – 8700 Å ) FOV = 11.5” × 7.3” (0.52” × 0.52” pixels) ~ 12”

12 Fig 1 ~ 30” × 40” Noyola+08 new kinematic center Anderson & van der Marel 2010 Previous GMOS IFU obs Constructed ARGUS images ~ 12”

13 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

14 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

15 Velocity dispersions Fig 3 core radius, r c = 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 r c 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 × 10 4 M ⊙ 0 M ⊙

16 Calculated χ 2 values for each model Noyola et al. (2008) : lower χ 2 values M ● = (5.2 ± 0.5) × 10 4 M ⊙ M ● = (4.75 ± 0.75) × 10 4 M ⊙ M ● = (3.0 ± 0.4) × 10 4 M ⊙

17 Velocity dispersions σ (100”) ∼ 17 km/s 7.5 × 10 4 M ⊙ 0 M ⊙ σ (center) ∼ 22.8 km/s

Noyola et al. 2008, ApJ, 676, 1008 (Fig 9) prediction : M ● = 1.3 × 10 4 M ⊙  sphere of influence ~ 5”

19 Thank you.

20 GCs with possible IMBHs Baumgardt et al. (2005, ApJ, 620, 238) M80 M62 M54 47 Tuc (N104) M10 (N6254)

21 BHs in GCs Safonova & Stalin (2010, NewA, 15, 450)

22 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