======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@aoc.nrao.edu http://www.aoc.nrao.edu/~gcnews ======================================================================== Vol. 28, No. 4 Mar 27, 2008 Recently submitted papers: -------------------------- 1) The Path to Buried Treasure: Paving the Way to the FLAMINGOS-2 Galactic Center Survey with IR and X-ray Observations (Bandyopadhyay et al., AIP) 2) The FLAMINGOS-2 Galactic Center Survey (Eikenberry, AIP) 3) FLAMINGOS-2: A Near-IR Multi-Object Spectrometer Ideal for Surveying the Galactic Center (Raines et al., AIP) 4) Non-uniform model for the synchrotron radiation of SgrA* and other low-luminosity galactic nuclei (Slysh, Astronomy reports) ------------------------------------------------------------------------ Email : reba@astro.ufl.edu Title : The Path to Buried Treasure: Paving the Way to the FLAMINGOS-2 Galactic Center Survey with IR and X-ray Observations Author(s): Reba M. Bandyopadhyay, Stephen S. Eikenberry, Curtis Dewitt Andrew J. Gosling Michael P. Muno and the F2GCS Team Institute: (1) Dept. of Astronomy, University of Florida, Gainesville, FL 32611 (2) Dept. of Astrophysics, University of Oxford, Oxford OX1 3RH, UK (3) California Institute of Technology, Pasadena, CA 91125 Paper : AIP Conf. Proc., 2008, in press EPrint : 0803.2721 Abstract: I describe the IR and X-ray campaign we have undertaken to determine the nature of the faint discrete X-ray source population discovered by \Chandra in the Galactic Center. These results will provide the input to the FLAMINGOS-2 Galactic Center Survey (F2GCS). With FLAMINGOS-2's multi-object IR spectrograph we will obtain 1000s of IR spectra of candidate X-ray source counterparts, allowing us to efficiently identify the nature of these sources, and thus dramatically increase the number of known X-ray binaries and CVs in the Milky Way. ------------------------------------------------------------------------ Email : reba@astro.ufl.edu Title : The FLAMINGOS-2 Galactic Center Survey Author(s): Stephen S. Eikenberry Institute: (1) Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, 32611 Paper : AIP Conf. Proc., 2008, in press EPrint : 0803.3084 Abstract: Upon commissioning on Gemini South, FLAMINGOS-2 will be one of the most powerful wide-field near-infrared imagers and multi-object spectrographs ev= er built for use on 8-meter-class telescopes. In order to take best advantage= of the strengths of FLAMINGOS-2 early in its life cycle, the instrument team h= as proposed to use 21 nights of Gemini guaranteed time in 3 surveys - the FLAMINGOS-2 Early Science Surveys (F2ESS). The F2ESS will encompass 3 corresponding science themes - the Galactic Center, galaxy evolution, and star formation. In this paper, I review the design performance and status = of FLAMINGOS-2, and describe the planned FLAMINGOS-2 Galactic Center Survey. ------------------------------------------------------------------------ Email : reba@astro.ufl.edu Title : FLAMINGOS-2: A Near-IR Multi-Object Spectrometer Ideal for Surveying the Galactic Center Author(s): S. Nicholas Raines, Stephen S. Eikenberry, and Reba M. Bandyopadhyay Institute: (1) University of Florida, Department of Astronomy, 211 Bryant Space Science Center, Gainesville, FL 32611 Paper : AIP Conf. Proc., 2008, in press EPrint : 0803.3083 Abstract: FLAMINGOS-2 (PI: S. Eikenberry) is a \5M facility-class near-infrared (1-2.5 micron ) multi-object spectrometer and wide-field imager being built at the University of Florida for Gemini South. Here we highlight the capabilities of FLAMINGOS-2, as it will be an ideal instrument for surveying the accreting binary population in the Galactic Center. ------------------------------------------------------------------------ Email : vslysh@asc.rssi.ru Title : Non-uniform model for the synchrotron radiation of SgrA* and other low-luminosity galactic nuclei Author(s): V. I. Slysh Institute: Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Moscow, Russia Paper : Astronomy reports, May 2008, in press Abstract: The model of a non-uniform source of synchrotron radiation with a power-law radial distribution of the magnetic field and relativistic-electron density along one- or two-sided jets is described. Non-relativistic jets with both constant cross sections (collimated jets) and the cross sections that are proportional to distance (conical jets) are considered. Formulas that can be used to determine source parameters from the spectral index, source size, and index of the relativistic-electron energy spectrum based on multi-frequency observations are obtained. In the case of a conical jet, these formulas coincide with the analogous formulas for a spherical source obtained by A.P.Marscher. Relations that can be used to estimate the magnetic-field strength from the brightness temperature in the self-absorbed region are also obtained. As examples, the non-uniform source model is applied to the compact radio sources at the centers of the Milky Way, SgrA*, and the low-luminosity galactic nuclei M81* and M87*, which are associated with supermassive black holes. The inner radius of the radiation region is determined. For SgrA*, this distance turns out to be comparable to the gravitational radius, smaller than the radius of the last stable orbit for non-rotating black hole, and consistent with the radius of the last stable orbit expected for a rotating black hole. The inner radii in M81* and M87* are 15 R_S, an order of magnitude larger then for SgrA*. Estimates of the magnetic field at the inner radius are 400 G for M81*, 0.65/5.3 kG for SgrA*, and 20/100 kG for M87*. These magnetic fields and the Blandford-Znajek model for the radiation of a rotating black hole are used to estimate the rotational speed of the black holes, which is in agreement with the characteristic variability time scales for these three objects. However, the accuracy of these estimates is modest, and is limited primarily by the accuracy of interferometric measurements at millimeter wavelengths. ------------------------------------------------------------------------ (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, Masaaki Sakano, Feng Yuan - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please follow the instructions which are at http://www.aoc.nrao.edu/~gcnews/home/submission.shtml ========================================================================