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Millimeter VLBI observations of Sgr A* and M87 with VERA and EHT

by Kazunori Akiyama (Univ. of Tokyo & NAOJ)

Dec 09, 2013 from 02:30 PM to 04:30 PM

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Abstract:

Despite the universality of accretion and outflow processes in a wide variety of astrophysical systems, much remains unknown about the detailed structure of the innermost regions of the accretion flow and relativistic jet in the vicinity of a supermassive black hole (SMBH). The SMBHs in the center of our Galaxy (Sgr A*) and the nearby active galaxy M87 are excellent laboratories to study these processes because the angular resolution attainable with short-mm VLBI corresponds to a few Schwarzschild radii for these sources (r_Sch = 10 microarcseconds and 7 microarcseconds for Sgr A* and M87, respectively). For Sgr A*, we present the results of 7-mm VLBI observations with VERA, a VLBI instrument in Japan.  We report the results of multi-epoch observations of Sgr A* in 2005-2008 as well as preliminary results from monitoring that resumed in January 2013 in order to trace the effects of the G2-cloud infall event. For M87 we show preliminary results of 1.3-mm VLBI observations with the Event Horizon Telescope in March 2012, during the middle of a period of enhancement in Very High Energy (VHE; > 200 MeV) emission. We briefly discuss implications for the structure of the M87 millimeter and VHE emission regions based on these results.

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