Sgr A* and Company -multiwavelength Observations of Sgr A* and Vla Search of " Sgr A*'s " in Liners
نویسنده
چکیده
We report first results from a multiwavelength campaign to measure the simultaneous spectrum of Sgr A* from cm to mm wavelengths. The observations confirm that the previously detected submm-excess is not due to variability; the presence of an ultracompact component with a size of a few Schwarzschild radii is inferred. In a VLA survey of LINER galaxies, we found Sgr A*-like nuclei in one quarter of the galaxies searched, suggesting a link between those low-power AGN and the Galactic Center.
منابع مشابه
X - ray and Radio Observations of SGR 1900 + 14 in the Immediate Aftermath of a Giant Flare
We present the results of Chandra, RXTE, and VLA observations of SGR 1900+14 in the immediate aftermath of its 2001 April 18 giant flare event. In the X-ray band we find the source in a pulsating and bursting state, with time-averaged 2–10 keV flux initially elevated by 20% above the source's previous quiescent periods. In the radio we establish upper limits on the strength of any persistent po...
متن کاملar X iv : a st ro - p h / 05 03 52 7 v 3 1 2 O ct 2 00 5 Simultaneous Multi - Wavelength Observations of Sgr A *
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 μm. The simultaneous ...
متن کاملThe Simultaneous Spectrum of Sgr A* from Λ20cm to Λ1mm and the Nature of the Mm-excess
We report results from a multiwavelength campaign to measure the simultaneous spectrum of the super-massive black hole candidate Sgr A* in the Galactic Center from cm to mm-wavelengths using the VLA, BIMA, the Nobeyama 45m, and the IRAM 30m telescopes. The observations confirm that the previously detected mmexcess is an intrinsic feature of the spectrum of Sgr A*. The excess can be interpreted ...
متن کاملDynamics of Ionized Gas at the Galactic Center: Very Large Array Observations of the Three-Dimensional Velocity Field and Location of the Ionized Streams in Sagittarius A West
We present new results based on high-resolution observations of Sgr A West at the Galactic center with the Very Large Array (VLA) at 1.3 cm. By combining recent observations with those made at earlier epochs with the VLA at wavelengths of 1.3 and 3.6 cm, we measured proper motions for 71 compact HII components in the central 80 (3 pc, assuming D = 8 pc). Using VLA archival data for the H92α rad...
متن کاملThe Linear Polarization of Sagittarius A
Synchrotron radiation from active galactic nuclei (AGN) is often highly polarized. We present a search for linear polarization with the Very Large Array (VLA) at 4.8 GHz and 8.4 GHz from the nearest AGN, Sagittarius A*. As a part of this study we used spectro-polarimetric data that were sensitive to a rotation measure (RM) as large as 3:5 10 6 rad m ?2 at 4.8 GHz and 1:5 10 7 rad m ?2 at 8.4 GH...
متن کامل