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VLT kinematics for Omega Centauri : Further support for a central BH

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).

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VLT kinematics for Omega Centauri : Further support for a central BH

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  1. 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)

  2. BHs – 3 kinds Stellar 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⊙)

  3. M●- σrelation Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)

  4. Tremaine et al. (2002, ApJ, 574, 740) IMBHs Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)

  5. ω Centauri RA(J2000) = 13 26 46 DEC = -47 28 37 (Harris 1996, AJ, 112, 1487) l = 309.10, b = 14.97 E(B-V) = 0.12 [Fe/H] = -1.62 d = 5.3 kpc 4.8±0.3 kpc(van de Ven+06) largest GC rt = 69 pc most massive GC 5.1×106 M⊙ 2.5×106 M⊙(van de Ven+06) MV = -10.3 most flattened GC (ε=1-b/a=0.19) N E MPI/ESO 2.2m/WFI (BVI) ~ 30’×30’

  6. NGC 1978 in LMC ε= 1-b/a = 0.33

  7. might be the stripped core of a dwarf galaxy 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) Y.-W. Lee et al. 1999, Nature, 402, 55

  8. BH in ωCentauri Noyola 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”

  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 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”

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

  13. Hot stars Fig 2 : spectral fit to the integrated spectra Exclude regions dominated by (1) hot stars with Paschen-series lines and (2) bright stars  ~15% of the pixels are excluded

  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, rc = 1.40’ = 84” (log 84 = 1.92) 7.5×104 M⊙ 0 M⊙ 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

  16. Calculated χ2values for each model M● = (3.0±0.4)×104 M⊙ M● = (5.2±0.5)×104 M⊙ M● = (4.75±0.75)×104 M⊙ Noyola et al. (2008) : lower χ2values

  17. Velocity dispersions σ(100”) ∼ 17 km/s 7.5×104 M⊙ 0 M⊙ σ(center) ∼ 22.8 km/s

  18. prediction : M● = 1.3×104 M⊙  sphere of influence ~ 5” Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)

  19. Thank you.

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

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

  22. Dark stellar remnants Dark stellar remnants Luminous component (e.g.) neutron stars, stellar mass BHs, massive WDs Noyola et al. 2008, ApJ, 676, 1008 (Fig 9)

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