======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@aoc.nrao.edu http://www.aoc.nrao.edu/~gcnews ======================================================================== Vol. 22, No. 7 Oct 27, 2005 Recently submitted papers: -------------------------- 1) Simultaneous Multi-Wavelength Observations of Sgr A* (An et al., ApJ) ------------------------------------------------------------------------ Email : antao@shao.ac.cn Title : Simultaneous Multi-Wavelength Observations of Sgr A* Author(s): T. An(1), W.M.Goss(2), Jun-Hui Zhao(3), X.Y. Hong(1), S. Roy(4), A.P. Rao(4), Z.-Q. Shen(1) Institute: (1) : Shanghai Astronomical Observatory, Chinese Academy of Science, Shanghai, 200030, PR China; antao@shao.ac.cn (2) : National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (3) : Harvard-Smithsonian CfA, 60 Garden St, MS 78, Cambridge, MA 02138 (4) : National Center for Radio Astrophysics (TIFR), Pune University Campus, Post Bag No. 3, Ganeshkhind, Pune 411 007, India Paper : ApJ Letter, October 2005, in press EPrint : astro-ph/0503527 Abstract: We observed Sgr A* using the Very Large Array (VLA) and the Giant Metrewave Radio Telescope (GMRT) at multiple cm and mm wavelengths on 17 June 2003. The measured flux densities of Sgr A*, together with those obtained from the Submillimeter Array (SMA) and the Keck II 10 m telescope on the same date, are used to construct a simultaneous spectrum of Sgr A* from 90 cm to 3.8 micron . The simultaneous spectrum shows a spectral break at about 3.6 cm, a possible signature of synchrotron self-absorption of the strong radio outburst which occurred near epoch 17 July 2003. At 90 cm, the flux density of Sgr A* is 0.22+/-0.06 Jy, suggesting a sharp decrease in flux density at wavelengths longer than 47 cm. The spectrum at long cm wavelengths appears to be consistent with free-free absorption by a screen of ionized gas with a cutoff 100 cm. This cutoff wavelength appears to be three times longer than that of 30 cm suggested by Davies, Walsh \& Booth based on observations in 1974 and 1975. Our analysis suggests that the flux densities of Sgr A* at wavelengths longer than 30 cm could be attenuated and modulated by stellar winds from massive stars close to Sgr A*. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Sera Markoff, Loránt Sjouwerman, Joseph Lazio, Cornelia Lang, Rainer Schödel, Robin Herrnstein - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please follow the instructions which are at http://www.aoc.nrao.edu/~gcnews/home/submission.shtml ========================================================================