THE INTRINSIC SHAPE OF SAGITTARIUS A* AT 3.5 mm WAVELENGTH
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; Lu, Ru-Sen; Montaña, Alfredo; Narayanan, Gopal; Rosenfeld, Katherine; Sánchez, David; Schloerb, F. Peter; Shen, Zhi-qiang; Shiokawa, Hotaka; Vertatschitsch, Laura; Doeleman, Sheperd Samuel; Fish, Vincent L.; SooHoo, Jason G; ... Show more Show less
DownloadOrtiz-Leon-2016-THE INTRINSIC SHAPE.pdf (1.197Mb)
PUBLISHER_POLICY
Publisher Policy
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.
Terms of use
Metadata
Show full item recordAbstract
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.
Date issued
2016-06Department
Haystack ObservatoryJournal
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
ISSN
1538-4357
0004-637X