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Short-term variability of Sgr A*

Published online by Cambridge University Press:  01 August 2006

M. R. Morris ,
S. D. Hornstein ,
A. M. Ghez ,
J. R. Lu ,
K. Matthews  and
F. K. Baganoff
M. R. Morris
Affiliation:
Dept. of Physics & Astronomy, Univ. of California, Los Angeles, CA 90095-1547, USA email: [email protected]
S. D. Hornstein
Affiliation:
Dept. of Physics & Astronomy, Univ. of California, Los Angeles, CA 90095-1547, USA email: [email protected]
A. M. Ghez
Affiliation:
Dept. of Physics & Astronomy, Univ. of California, Los Angeles, CA 90095-1547, USA email: [email protected]
J. R. Lu
Affiliation:
Dept. of Physics & Astronomy, Univ. of California, Los Angeles, CA 90095-1547, USA email: [email protected]
K. Matthews
Affiliation:
Caltech Optical Observatories, California Institute of Technology, Mail Code 105-24, Pasadena, CA 91125, USA
F. K. Baganoff
Affiliation:
Center for Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Abstract

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Observations of Sgr A* over the past 4 years with the Keck Telescope in the near-infrared, coupled with millimeter and submillimeter observations, show that the 3.7×106M⊙ Galactic Black Hole, Sagittarius A*, displays continuous variability at all these wavelengths, with the variability power concentrated on characteristic time scales of a few hours, and with a variability fraction that increases with wavelength. We review the observations indicating that the few-hour time scale for variability is reproduced at all accessible wavelengths. Interpreted as a dynamical time, this time scale corresponds to a radial distance of 2 AU, or ∼25 Schwarzschild radii. Searches for quasi-periodicities in the near-infrared data from the Keck Telescope have so far been negative. One interpretation of the character of these variations is that they result from a recurring disk instability, rather than from variations in the mass accretion rate flowing through the outer boundary of the emission region. However, neither a variable accretion rate nor a mechanism associated with a jet can presently be ruled out.

Keywords

Galaxy: nucleus – black hole physics – accretion disks
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S238: Black Holes from Stars to Galaxies – Across the Range of Masses , August 2006 , pp. 195 - 200
Copyright
Copyright © International Astronomical Union 2007

References

Baganoff, F. K. et al. 2001, Nature, 413, 45CrossRefGoogle Scholar
Baganoff, F. K. 2005, KITP Conference: Paradoxes of Massive Black Holes: A Case Study in the Milky Way, http://online.kitp.ucsb.edu/online/galactic_c05/baganoffGoogle Scholar
Belanger, G. et al. 2005, ApJ, 635, 1095Google Scholar
Belanger, G., Terrier, R.de Jager, O. C.Goldwurm, A. & Melia, F. 2006, in: Schödel, R.Bower, G. C.Muno, M. P.Nayakshin, S. & Ott, T. (eds.), J. Phys. Conf. Ser., 54, 420Google Scholar
Brown, R. L. & Lo, K. Y. 1982, ApJ, 253, 225CrossRefGoogle Scholar
Eckart, A. et al. 2004, A&A, 427, 1Google Scholar
Eckart, A. et al. 2006, A&A, 450, 535Google Scholar
Genzel, R. et al. 2003, Nature, 425, 943CrossRefGoogle Scholar
Ghez, A. M. et al. 2004, ApJL, 601, L159CrossRefGoogle Scholar
Herrnstein, R. M., Zhao, J.-H., Bower, G. C. & Goss, W. M. 2004, AJ, 127, 3399Google Scholar
Hornstein, S. et al. 2004, in: Schödel, R.Bower, G. C.Muno, M. P.Nayakshin, S. & Ott, T. (eds.), J. Phys. Conf. Ser., 54, 399Google Scholar
Hornstein, S. et al. 2007, ApJ, submittedCrossRefGoogle Scholar
Macquart, J.-P. & Bower, G. C. 2006, ApJ, 641, 302CrossRefGoogle Scholar
Marrone, D. P., Moran, J. M., Zhao, J.-H. & Rao, R. 2006a, ApJ, 640, 308CrossRefGoogle Scholar
Marrone, D. P., Moran, J. M., Zhao, J.-H. & Rao, R. 2006b, in: Schödel, R., Bower, G. C.Muno, M. P.Nayakshin, S. & Ott, T. (eds.), J. Phys. Conf. Ser., 54, 354Google Scholar
Mauerhan, J. C., Morris, M., Walter, F. & Baganoff, F K. 2005, ApJL, 623, L25Google Scholar
Miyazaki, A., Tsutsumi, T. & Tsuboi, M. 2004, ApJL, 611, L97Google Scholar
Miyazaki, A., Shen, Z.-Q., Miyoshi, M.Tsuboi, M. & Tsutsumi, T. 2006, in: Schödel, R.Bower, G. C.Muno, M. P.Nayakshin, S. & Ott, T. (eds.), J. Phys. Conf. Ser., 54, 363Google Scholar
Yusef-Zadeh, F., Roberts, D.Wardle, M.Heinke, C. O. & Bower, G. C. 2006a, ApJ, 650, 189Google Scholar
Yusef-Zadeh, F. et al. 2006b, ApJ, 644, 198CrossRefGoogle Scholar
Zhao, J.-H., Ekers, R. D.Goss, W. M.Lo, K. Y. & Narayan, R. 1989, in: Morris, M. (ed.), The Center of the Galaxy (Kluwer: Dordrecht), p. 535Google Scholar
Zhao, J.-H.Goss, W. M.Lo, K. Y. & Ekers, R. D. 1992, in: Filippenko, A. (ed.), Relationships Between Active Galactic Nuclei and Starburst Galaxies, ASP Conference Series, vol. 31, p. 295Google Scholar