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Intrinsic Size and Shape of Sgr A*: 3.6 AU by <1 AU

K. Y. Lo·Z. -Q. Shen·J. -H. Zhao·Paul~T. P. Ho
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Abstract

By means of near-simultaneous multi-wavelength VLBA measurements, we determine for the first time the intrinsic size of Sgr A* to be 3.6 AU by <1 AU with the major axis oriented essentially north-south. Contrary to previous expectation that the intrinsic structure of Sgr A* is observable only at wavelength shorter than 1 mm, we can discern the intrinsic source size at 7~mm because (1) the scattering size along the minor axis is half that along the major axis, and (2) the near simultaneous multi-wavelength mapping of Sgr A* makes it possible to extrapolate precisely the minor axis scattering angle at 7~mm. The intrinsic size and shape place direct constraints on the various theoretical models for Sgr A*.

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K. Y. Lo, Z. -Q. Shen, J. -H. Zhao, Paul~T. P. Ho. 1998-11-24. Intrinsic Size and Shape of Sgr A*: 3.6 AU by <1 AU. https://arxiv.org/abs/astro-ph/9811375

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