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Imaging an Event Horizon: Mitigation of Scattering toward Sagittarius A*

Fish, Vincent L. and Johnson, Michael D. and Lu, Ru-Sen and Doeleman, Sheperd S. and Bouman, Katherine L. and Zoran, Daniel and Freeman, William T. and Psaltis, Dimitrios and Narayan, Ramesh and Pankratius, Victor and Broderick, Avery E. and Gwinn, Carl R. and Vertatschitsch, Laura E. (2014) Imaging an Event Horizon: Mitigation of Scattering toward Sagittarius A*. Astrophysical Journal, 795 (2). Art. No. 134. ISSN 1538-4357.

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The image of the emission surrounding the black hole in the center of the Milky Way is predicted to exhibit the imprint of general relativistic (GR) effects, including the existence of a shadow feature and a photon ring of diameter ~50 μas. Structure on these scales can be resolved by millimeter-wavelength very long baseline interferometry. However, strong-field GR features of interest will be blurred at λ ≥ 1.3 mm due to scattering by interstellar electrons. The scattering properties are well understood over most of the relevant range of baseline lengths, suggesting that the scattering may be (mostly) invertible. We simulate observations of a model image of Sgr A* and demonstrate that the effects of scattering can indeed be mitigated by correcting the visibilities before reconstructing the image. This technique is also applicable to Sgr A* at longer wavelengths.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Fish, Vincent L.0000-0002-7128-9345
Johnson, Michael D.0000-0002-4120-3029
Lu, Ru-Sen0000-0002-7692-7967
Doeleman, Sheperd S.0000-0002-9031-0904
Bouman, Katherine L.0000-0003-0077-4367
Freeman, William T.0000-0002-2231-7995
Narayan, Ramesh0000-0002-1919-2730
Broderick, Avery E.0000-0002-3351-760X
Additional Information:© 2014. The American Astronomical Society. Received 2014 June 20; accepted 2014 September 15; published 2014 October 22. The Event Horizon Telescope is supported by grants from the National Science Foundation (NSF) and from the Gordon and Betty Moore Foundation (#GBMF-3561). K.L.B. is partially supported by an NSF Graduate Fellowship. D.P. is supported by NASA/NSF TCAN award NNX14AB48G and by NSF award AST 1312034. R.N. was supported in part by NSF grant AST 1312651. A.E.B. receives financial support from the Perimeter Institute for Theoretical Physics and the Natural Sciences and Engineering Research Council of Canada through a Discovery Grant. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research and Innovation.
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Gordon and Betty Moore FoundationGBMF-3561
Perimeter Institute for Theoretical PhysicsUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Industry CanadaUNSPECIFIED
Ontario Ministry of Research and InnovationUNSPECIFIED
Subject Keywords:galaxies: individual (Sgr A*) ; Galaxy: center; scattering; techniques: image processing; techniques: interferometric
Issue or Number:2
Record Number:CaltechAUTHORS:20190405-150444181
Persistent URL:
Official Citation:Vincent L. Fish et al 2014 ApJ 795 134
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94517
Deposited By: George Porter
Deposited On:05 Apr 2019 23:04
Last Modified:03 Oct 2019 21:04

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