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http://hdl.handle.net/20.500.12386/31829
Title: | Persistent Non-Gaussian Structure in the Image of Sagittarius A* at 86 GHz | Authors: | Issaoun, S. Johnson, M. D. Blackburn, L. Broderick, A. Tiede, P. Wielgus, M. Doeleman, S. S. Falcke, H. Akiyama, K. Bower, G. C. Brinkerink, C. D. Chael, A. Cho, I. Gómez, J. L. Hernández-Gómez, A. Hughes, D. Kino, M. Krichbaum, T. P. LIUZZO, Elisabetta Teodorina Loinard, L. Markoff, S. Marrone, D. P. Mizuno, Y. Moran, J. M. Pidopryhora, Y. Ros, E. RYGL, Kazi Lucie Jessica Shen, Z. -Q. Wagner, J. |
Issue Date: | 2021 | Journal: | THE ASTROPHYSICAL JOURNAL | Number: | 915 | Issue: | 2 | First Page: | 99 | Abstract: | Observations of the Galactic Center supermassive black hole Sagittarius A* (Sgr A*) with very long-baseline interferometry (VLBI) are affected by interstellar scattering along our line of sight. At long radio observing wavelengths (≲1 cm), the scattering heavily dominates image morphology. At 3.5 mm (86 GHz), the intrinsic source structure is no longer sub-dominant to scattering, and thus the intrinsic emission from Sgr A* is resolvable with the Global Millimeter VLBI Array (GMVA). Long-baseline detections to the phased Atacama Large Millimeter/submillimeter Array (ALMA) in 2017 provided new constraints on the intrinsic and scattering properties of Sgr A*, but the stochastic nature of the scattering Requires multiple observing epochs to reliably estimate its statistical properties. We present new observations with the GMVA+ALMA, taken in 2018, which confirm non-Gaussian structure in the scattered image seen in 2017. In particular, the ALMA-GBT baseline shows more flux density than expected for an anistropic Gaussian model, providing a tight constraint on the source size and an upper limit on the dissipation scale of interstellar turbulence. We find an intrinsic source extent along the minor axis of ~100 μas both via extrapolation of longer wavelength scattering constraints and direct modeling of the 3.5 mm observations. Simultaneously fitting for the scattering parameters, we find an at-most modestly asymmetrical (major-to-minor axis ratio of 1.5 ± 0.2) intrinsic source morphology for Sgr A*. | URI: | http://hdl.handle.net/20.500.12386/31829 | URL: | https://iopscience.iop.org/article/10.3847/1538-4357/ac00b0 https://api.elsevier.com/content/abstract/scopus_id/85111100841 |
ISSN: | 0004-637X | DOI: | 10.3847/1538-4357/ac00b0 | Bibcode ADS: | 2021ApJ...915...99I | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
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2104.07610.pdf | preprint | 3.56 MB | Adobe PDF | View/Open |
Issaoun_2021_ApJ_915_99-1-7.pdf | [Administrators only] | 7.38 MB | Adobe PDF | |
Issaoun_2021_ApJ_915_99-8-14.pdf | [Administrators only] | 6.55 MB | Adobe PDF |
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