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arXiv · 1608.06515

Asymmetric structure in Sgr A* at 3mm from closure phase measurements with VLBA, GBT and LMT

Christiaan D. Brinkerink·Cornelia Müller·Heino Falcke·Geoffrey C. Bower·Thomas P. Krichbaum·Edgar Castillo·Adam T. Deller·Sheperd S. Doeleman·Raquel Fraga-Encinas·Ciriaco Goddi·Antonio Hernández-Gómez·David H. Hughes·Michael Kramer·Jonathan León-Tavares·Laurent Loinard·Alfredo Montaña·Monika Mościbrodzka·Gisela N. Ortiz-León·David Sanchez-Arguelles·Remo P. J. Tilanus·Grant W. Wilson·J. Anton Zensus
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Abstract

We present the results of a closure phase analysis of 3 mm very long baseline interferometry (VLBI) measurements performed on Sagittarius A* (Sgr A*). We have analyzed observations made in May 2015 using the Very Long Baseline Array, the Robert C. Byrd Green Bank Telescope and the Large Millimeter Telescope Alfonso Serrano and obtained non-zero closure phase measurements on several station triangles - indicative of a non-point-symmetric source structure. The data are fitted with an asymmetric source structure model in Sgr A*, represented by a simple two-component model, which favours a fainter component due East of the main source. This result is discussed in light of a scattering screen with substructure or an intrinsically asymmetric source.

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Christiaan D. Brinkerink, Cornelia Müller, Heino Falcke, Geoffrey C. Bower, Thomas P. Krichbaum, Edgar Castillo, Adam T. Deller, Sheperd S. Doeleman, Raquel Fraga-Encinas, Ciriaco Goddi, Antonio Hernández-Gómez, David H. Hughes, Michael Kramer, Jonathan León-Tavares, Laurent Loinard, Alfredo Montaña, Monika Mościbrodzka, Gisela N. Ortiz-León, David Sanchez-Arguelles, Remo P. J. Tilanus, Grant W. Wilson, J. Anton Zensus. 2016-08-23. Asymmetric structure in Sgr A* at 3mm from closure phase measurements with VLBA, GBT and LMT. https://doi.org/10.1093/mnras%2Fstw1743

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