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

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.

arXiv commentTo be published in MNRAS. First published online July 19, 2016

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• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• The Size, Shape, and Scattering of Sagittarius A* at 86 GHz: First VLBI with ALMA
• The Scattering and Intrinsic Structure of Sagittarius A* at Radio Wavelengths
• General relativistic magnetohydrodynamical $\kappa$-jet models for Sgr A*
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• Simulations of imaging the event horizon of Sagittarius A* from space
• Stochastic Optics: A Scattering Mitigation Framework for Radio Interferometric Imaging
• Observing supermassive black holes in virtual reality
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• Symmetric Achromatic Variability in Active Galaxies -- A Powerful New Gravitational Lensing Probe?
• The intrinsic structure of Sagittarius A* at 1.3 cm and 7 mm
• Persistent Non-Gaussian Structure in the Image of Sagittarius A* at 86 GHz
• Polarization images of accretion flow around supermassive black holes: imprints of toroidal field structure
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• General relativistic effects and the near-infrared and X-ray variability of Sgr A* I
• ALMA and VLA observations of emission from the environment of Sgr A*
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• An independent hybrid imaging of Sgr A* from the data in EHT 2017 observations
• A proof-of-concept neural network for inferring parameters of a black hole from partial interferometric images of its shadow