======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@mpifr-bonn.mpg.de http://www.mpifr-bonn.mpg.de/gcnews ======================================================================== Vol. 12, No. 13 Sep 28, 2000 Recently submitted papers: -------------------------- 1) UHECR Production and Curvature TeV Emission in Nearby, Dormant AGNs (Levinson, proceedings) 2) Unusual Properties of X-Ray Emission near the Galactic Center (Tanaka et al., PASJ) ------------------------------------------------------------------------ Email : levinson@wise1.tau.ac.il Title : UHECR Production and Curvature TeV Emission in Nearby, Dormant AGNs Author(s): Amir Levinson Institute: (1) School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel Paper : proceedings of the Heidelberg Workshop "High Energy Gamma-Ray Astronomy" EPrint : astro-ph/0009383 Abstract: The possibility that rapidly rotating supermassive black holes associated with quasar remnants may provide sites for the acceleration of ultra-high energy cosmic rays (UHECRs) is considered. It is shown that prodigious TeV emission through curvature losses is an important consequence of this mechanism. Given the measured UHECR flux, it is expected that nearby dormant AGNs will be detectable by current Tev experiments. The implications for the Sgr A* source are also briefly considered. ------------------------------------------------------------------------ Email : maeda@cubic.astro.psu.edu Title : Unusual Properties of X-Ray Emission near the Galactic Center Author(s): Y. Tanaka(1,2), K. Koyama(3), Y. Maeda(4), T. Sonobe(5) Institute: (1) The Institute of Space \& Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (2) Max-Planck Institut fuer Extraterrestrische Physik, D-85748 Garching, Germany (3) Dept. of Physics, Kyoto University, Sakyo-ku, Kyoto 606-01 (4) Dept. of Astronomy \& Astrophysics, Penn State University, University Park, PA 16802-6305, U.S.A. (5) Fujitsu Ltd., 4-1-1 Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa 211-8588 Paper : PASJ, 52, L25-L30 (2000) EPrint : astro-ph/0009445 Abstract: The X-ray spectrum in a 1^o*1^o region of the Galactic center observed with the ASCA satellite is examined in detail, following the first report by Koyama et al. (1996, AAA 65.155.208). The observed spectrum contains prominent emission lines from helium-like and hydrogen-like ions of various elements, and is essentially the same all over the region. If the observed spectrum is thermal emission from hot plasmas, it requires multi-temperature plasma components, each at a different degree of ionization and with a different amount of absorption. The absence of adiabatic cooling and of systematic changes in the degree of ionization over the region is against the Galactic center origin of hot plasmas. A significant broadening of the helium-like and hydrogen-like iron K-lines is confirmed. The line width corresponds to a rms velocity of 3300 km s^-1, which far exceeds the sound velocity in a plasma of kT 14 keV measured with the Ginga satellite. These facts cast doubt on a thermal origin of the observed X-ray emission. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Angela Cotera Heino Falcke & Sera Markoff (cotera@as.arizona.edu) (hfalcke,smarkoff@mpifr-bonn.mpg.de) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please send the (La)Tex file of your paper to gcnews@mpifr-bonn.mpg.de ========================================================================