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NIR Emission and Flares from Sgr A*

NIR Emission and Flares from Sgr A*. R. Schödel, A.Eckart Universität zu Köln. R. Genzel MPE, Garching. Gravitational Potential near SgrA*. 3.35( ±0.15 ) x 10 6 M sol point mass plus visible star cluster ( χ 2 red = 1.02). enclosed mass (solar masses). dark cluster

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NIR Emission and Flares from Sgr A*

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  1. NIR Emission and Flares from Sgr A* R. Schödel, A.Eckart Universität zu Köln R. Genzel MPE, Garching

  2. Gravitational Potential near SgrA*

  3. 3.35(±0.15) x 106 Msol point mass plus visible star cluster (χ2red = 1.02) enclosed mass (solar masses) dark cluster ρ0 = 1.6x1018 Msol pc-3 α = 5 visible star cluster ρ0 = 1.5 x 106 Msol pc-3 rcore = 0.46 pc, α = 1.7 radius (parsec)

  4. S2 orbit in non-Keplerian potential Search for Extended Mass • Best fit: • Mtot = 4.1 x 106 solar masses • thereof 10% extended • M/L > 90 could be explained e.g. by cluster of stellar mass BHs • (Miralda-Escudé & Gould, 2000) Mouawad et al., 2004, submitted

  5. Sgr A* „… and beyond, infinity“ 2001, A Space Odyssey NIR emission from Sagittarius A*

  6. SgrA* NIR flares! NACO/VLT 8/9 May 2003 1.7 μm

  7. SgrA* NIR flares! • VLT: 1.7 – 3.8 μm flares from SgrA*; Keck 3.8 μm • Similar to X-ray flares (Baganoff et al., 2001) • position within < 10 mas from Sgr A* • Frequency: 3 - 6/day! • Factors 1.5 (3.8 μm) to 6 (1.7 μm ) • Time scales  origin <10 RS of 3.6x106 Msol BH Genzel et al. 2003, Nature; Ghez et al., 2003

  8. SgrA* SED and models Genzel et al. 2003, Nature, in press Ghez et al. 2003, ApJ Lett submitted Radio: Zhao, Falcke, Bower, Aitken, et al. 1999-2003 X-ray: Baganoff et al. 2001, 2003, Goldwurm et al. 2003, Porquet et al. 2003, models: Markoff, Falcke, Liu, Melia, Narayan, Quataert, Yuan et al. 1999-2001

  9. NIR flares: quasi-periodicity Genzel et al. 2003, Nature

  10. 3 0 o r b i t a l p e r i o d a t l a s t s t a b l e o r b i t orbital period at last stable orbit 2 0 ) n i m ( o t s l T 1 0 a’=0.52 (±0.1,±0.07,±0.14) 0 T (min) 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 a / ( G M / c ) a‘ = 0.52 (±0.1, ±0.07,±0.14) a/(GM/c) Spin measurement of Sgr A*? • Period at last stable orbit for 3.6 x106 Msol • Schwarzschild BH: 27 min • Orbital frequency is shortest one of all expected frequencies • near a BH. • Interpretation of ~17 min quasi-periodicity: emission from accreting matter near LSO of spinning (Kerr) BH Genzel et al., NATURE 2003

  11. SgrA*: K-band flare and quiescent emission NACO/VLT June 16, 2003

  12. Sgr A*, June 20, 2003 First Simultaneous NIR/X-rayObservation of Sgr A* Eckart, Morris, Baganoff, et al., submitted to A&A; available on astro-ph

  13. March 1996 SHARP/NTT S2 S8 10-3 Janskys SgrA* Minutes Flare Activity in the Past Consistent with our current knowledge of flares!

  14. To be continued… 2004 will be the international year of SgrA*.

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