The Intrinsic Size of Sagittarius A* from 0.35 cm to 6 cm
Geoffrey C. Bower1, W.M. Goss2, Heino Falcke3, Donald C. Backer1, Yoram Lithwick4
(1) Astronomy Department & Radio Astronomy Laboratory, University of California, Berkeley, CA 94720
(2) National Radio Astronomy Observatory, P.O. Box 0, Socorro NM 87801, U.S.A.
(3) ASTRON, Postbus 2, 7990 AA Dwingeloo, The Netherlands and Department of Astrophysics, Radboud Universiteit Nijmegen, Postbus 9010, 6500 GL Nijmegen, The Netherlands
(4) CITA, University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 3H8
Paper: ApJL in press
Abstract:
We present new high-resolution observations of Sagittarius A* at
wavelengths of 17.4 to 23.8 cm with the Very Large Array in A configuration
with the Pie Town Very Long Baseline Array antenna. We use the
measured sizes to calibrate the interstellar scattering law and find
that the major axis size of the scattering law is smaller by 6%
than previous estimates. Using
the new scattering law, we are able to determine the intrinsic size of
Sgr A* at wavelengths from 0.35 cm to 6 cm using existing results from
the VLBA. The new law increases the intrinsic size at 0.7 cm by
20% and < 5% at
0.35 cm. The intrinsic size is 13+7_-3 Schwarzschild radii at
0.35 cm and is proportional to lambda gamma , where gamma is in the
range 1.3 to 1.7.
Preprints available from the authors at gbower@astro.berkeley.edu
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