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Chandra Observations of Sgr A*

Chandra Observations of Sgr A*. Frederick Baganoff. Massachusetts Institute of Technology. Chandra Galactic Center Deep Field. 17 x 17 arcmin 40 x 40 pc 590 ks. Red 2-3.7 keV Green 3.7-4.5 keV Blue 4.5-8 keV. Chandra Galactic Center Deep Field. 8.4 x 8.4 arcminutes.

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Chandra Observations of Sgr A*

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  1. Chandra Observations of Sgr A* Frederick Baganoff Massachusetts Institute of Technology

  2. Chandra Galactic Center Deep Field 17 x 17 arcmin 40 x 40 pc 590 ks Red 2-3.7 keV Green 3.7-4.5 keV Blue 4.5-8 keV

  3. Chandra Galactic Center Deep Field 8.4 x 8.4 arcminutes

  4. Chandra 3-Color Image of the Central Parsec

  5. VLA 6 cm Image of Sgr A West Minispiral

  6. Radio Image of Sgr A West and Circumnuclear Disk Red: HCN Blue: 6 cm

  7. X-ray Image and 6 cm Contours of Sgr A West

  8. 2000 October 26-27 (Baganoff et al. 2001) Oct 27 05:42 UT 45x, 4 hr

  9. Multiwavelength Monitoring of the Supermassive Black Hole in the Galactic Center F.K. Baganoff1 M.W. Bautz1, G.R. Ricker1, W.N. Brandt2, G. Chartas2, E.D. Feigelson2, G.P. Garmire2,M. Morris3, E.E. Becklin3, A.M. Ghez3, S.D. Hornstein3, A.M. Tanner3, A.S. Cotera4, P.M. Hinz4, W.F. Hoffmann4, M.R. Meyer4, A. Eckart5, R. Genzel6, J.-H. Zhao7, R.M. Herrnstein7, J.L. Hora7, J.-P. Macquart8, Y. Maeda9, R.J. Sault10, G.B. Taylor11, F. Walter11 1MIT, 2UCLA, 3Penn State, 4Steward Obs., 5U. Cologne, 6MPE, 7CfA, 8U. Groningen, 9ISAS, 10ATNF, 11NRAO

  10. Observatories Participating in Sgr A* Monitoring Campaign • Chandra (12-62 nm) • Keck (2 & 10 mm) • Very Large Telescope (3-5 mm) • Magellan (10 mm) • Submillimeter Array (1.3 mm) • Caltech OVRO Millimeter Array (3 mm) • Australia Telescope Compact Array (3 mm) • Very Large Baseline Array (7 mm) • Very Large Array (7mm, 1.3 cm, 2 cm)

  11. 2002 May 22-23 – Orbit 1, Part 1

  12. 2002 May 24 – Orbit 1, Part 2 May 24 19:42 UT 5x, 1.7 hr

  13. 2002 May 25-27 – Orbit 2 May 26 04:24 UT 6x, 0.75 hr May 24 19:42 UT 5x, 1 hr May 26 13:47 UT 5x, 0.5 hr

  14. 2002 May 28-30 – Orbit 3 May 28 15:36 UT 25x, 1 hr May 29 18:33 UT 13x, 0.5 hr May 29 06:03 UT 12x, 1.5 hr

  15. 2002 June 3-4 – Orbit 5

  16. Sgr A* Multiwavlength Monitoring Campaign

  17. Three Large X-ray Flares from Sgr A*

  18. Very Long Baseline Array – 7 mm • No significant flux variability detected (upper limit about 30%) • No extended structure appeared within 5 hour track (upper limit about 10 mJy)

  19. NH = 6.0 x 1022 cm-2 G = 1.3 (0.9-1.8) FX = 1.6 x 10-12 erg cm-2 s-1 LX = 2.0 x 1034 erg s-1 D = 8 kpc Model: Absorbed, Dust-Scattered Power Law Integrated X-ray Spectrum of Sgr A* Flares

  20. Summary - Sgr A* Flares • Chandra observed Sgr A* for 139 hr over a two-week period in late May to early June 2002 • 3 X-ray flares with amplitudes >10x detected in a 28-hr period • 4 X-ray flares with amplitudes ~5x detected in addition • Typical flare duration is about 1 hr (0.5-4 hr) • XMM-Newton has detected 2 large X-ray flares (Goldwurm et al. 2002; Porquet et al. 2003) • Amplitudes, durations, and rise/fall timescales similar to Chandra flares • First flare had hard spectrum G ~ 1.1 • Second flare - brightest to date (90x) - has soft spectrum G ~ 2.5 • Distribution of flare properties? Different physical conditions?

  21. Summary - Sgr A* Flares (continued) • Strong X-ray flares occur about once per day • Observed frequent, large-amplitude, short-duration flaring behavior of Sgr A* is unique among SMBHs • Probably selection effect: flares too faint to detect in other galaxies • Behavior inconsistent with X-ray binaries and not seen from any of the other >2,300 X-ray point sources in the field

  22. Integrated X-ray Spectrum of Sgr A* Quiescent Emission Model: Absorbed, Dust-Scattered, NIE Plasma NH = 5.9 x 1022 cm-2 G = 4-5 keV EFe = 6.59 (6.54-6.64) keV Line is narrow and NIE FX = 1.8 x 10-13 erg cm-2 s-1 LX = 1.4 x 1033 erg s-1 D = 8 kpc <LF> / <LQ> = 14.0

  23. Radial Profile of Central 10 Arcseconds Slope = 1.0

  24. Chandra Lightcurve of Sgr A* Eckart, Baganoff et al. (2004) 2-8 keV 19-20 June 2003 Counts per second Minutes

  25. VLT Lightcurve of Sgr A* 19-20 June 2003 2.2um Eckart, Schoedel, et al.

  26. VLT AO Images Sgr A* bright Sgr A* bright Sgr A* dim

  27. Bayesian Blocks Representation of X-ray Lightcurve • Excess amplitude ~x2 • Duration ~40-60 min • 99.923% confidence Scargle (1998)

  28. X-ray and NIR Lightcurves • First simultaneous detection of X-ray and NIR flare • At least in this case, X-ray and NIR photons appear to come from a single electron population • Lx ~ 6x1033 erg/s • Lnir ~ 5x1034 erg/s • Spectral index ~ 1.3 • X-rays coincident within 180 mas • NIR coincident within 14 mas • X-ray flares from Sgr A*

  29. Sgr A* and X-ray Transients in the Central Arcminute of the Galaxy 1 hour / frame 6 days 17 hours

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