THE INTRINSIC SHAPE OF SAGITTARIUS A* AT 3.5 mm WAVELENGTH
Name
Ortiz-Leon-2016-THE INTRINSIC SHAPE.pdf
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1.2 MB
Format
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Checksum (MD5)
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Author(s)
Ortiz-León, Gisela N.
Johnson, Michael D.
Blackburn, Lindy
Loinard, Laurent
Reid, Mark J.
Castillo, Edgar
Chael, Andrew A.
Hernández-Gómez, Antonio
Hughes, David H.
León-Tavares, Jonathan
Date Issued
June 2016
Journal
Astrophysical Journal
Publisher
IOP Publishing
Citation
Ortiz-León, Gisela N., Michael D. Johnson, Sheperd S. Doeleman, Lindy Blackburn, Vincent L. Fish, Laurent Loinard, Mark J. Reid, et al. “THE INTRINSIC SHAPE OF SAGITTARIUS A* AT 3.5 Mm WAVELENGTH.” The Astrophysical Journal, vol. 824, no. 1, 40, June 2016, pp. 40. © 2016. The American Astronomical Society.
Version
Final published version
Abstract
The radio emission from Sgr A* is thought to be powered by accretion onto a supermassive black hole of ~4 x 10⁶M⊙ at the Galactic Center. At millimeter wavelengths, Very Long Baseline Interferometry (VLBI) observations can directly resolve the bright innermost accretion region of Sgr A*. Motivated by the addition of many sensitive long baselines in the north–south direction, we developed a full VLBI capability at the Large Millimeter Telescope Alfonso Serrano (LMT). We successfully detected Sgr A* at 3.5 mm with an array consisting of six Very Long Baseline Array telescopes and the LMT. We model the source as an elliptical Gaussian brightness distribution and estimate the scattered size and orientation of the source from closure amplitude and self-calibration analysis, obtaining consistent results between methods and epochs. We then use the known scattering kernel to determine the intrinsic two-dimensional source size at 3.5 mm: (147 ∓ 7 μas) x (120 ∓ 12 μas), at position angle 88° ∓ 7° east of north. Finally, we detect non-zero closure phases on some baseline triangles, but we show that these are consistent with being introduced by refractive scattering in the interstellar medium and do not require intrinsic source asymmetry to explain.
MIT Department
Haystack Observatory
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.3847/0004-637x/824/1/40
