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Cited by 105Astrophysical Phenomena and ObservationsAstrophysics and Cosmic PhenomenaRadio Astronomy Observations and Technology

The DOI matches its Crossref record; 90 of the 90 references it cites were found in a registry or an index.

The Scattering and Intrinsic Structure of Sagittarius A* at Radio Wavelengths

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Johnson, Michael D., Narayan, Ramesh, Psaltis, Dimitrios, Blackburn, Lindy, Kovalev, Yuri Y., Gwinn, Carl R., Zhao, Guang-Yao, Bower, Geoffrey C., Moran, James M., Kino, Motoki, Kramer, Michael, Akiyama, Kazunori, Dexter, Jason, Broderick, Avery E., Sironi, Lorenzo·2018·The Astrophysical Journal
DOI 10.3847/1538-4357/aadcff
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Abstract

Radio images of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), are dominated by interstellar scattering. Previous studies of Sgr A* have adopted an anisotropic Gaussian model for both the intrinsic source and the scattering, and they have extrapolated the scattering using a purely λ 2 scaling to estimate intrinsic properties. However, physically motivated source and scattering models break all three of these assumptions. They also predict that refractive scattering effects will be significant, which have been ignored in standard model fitting procedures. We analyze radio observations of Sgr A* using a physically motivated scattering model, and we develop a prescription to incorporate refractive scattering uncertainties when model fitting. We show that an anisotropic Gaussian scattering kernel is an excellent approximation for Sgr A* at wavelengths longer than 1 cm, with an angular size of along the major axis, along the minor axis, and a position angle of . We estimate that the turbulent dissipation scale is at least 600 km, with tentative support for r in = 800 ± 200 km, suggesting that the ion Larmor radius defines the dissipation scale. We find that the power-law index for density fluctuations in the scattering material is β < 3.47, shallower than expected for a Kolmogorov spectrum ( β = 11/3), and we estimate in the case of r in = 800 km. We find that the intrinsic structure of Sgr A* is nearly isotropic over wavelengths from 1.3 mm to 1.3 cm, with a size that is roughly proportional to wavelength: . We discuss implications for models of Sgr A*, for theories of interstellar turbulence, and for imaging Sgr A* with the Event Horizon Telescope.

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Research works printed but not linked: 6

  1. Celnikier, 1983, A&A, 126, 293
  2. Falcke, 2000, A&A, 362, 113
  3. Iroshnikov, 1964, SvA, 7, 566
  4. Krichbaum, 1998, A&A, 335, L106
  5. Krichbaum, 1993, A&A, 274, L37
  6. Psaltis, 2018, ApJ

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Metadata

Authors
Johnson, M. D., Narayan, R., Psaltis, D., Blackburn, L., Kovalev, Y. Y., Gwinn, C. R., Zhao, G.-Y., Bower, G. C., Moran, J. M., Kino, M., Kramer, M., Akiyama, K., Dexter, J., Broderick, A. E., & Sironi, L.
Affiliations
  • Center for Astrophysics Harvard & Smithsonian (US)
  • University of Arizona (US)
  • P.N. Lebedev Physical Institute of the Russian Academy of Sciences (RU)
  • University of California, Santa Barbara (US)
  • Korea Astronomy and Space Science Institute (KR)
  • Institute of Astronomy and Astrophysics, Academia Sinica (TW)
  • Kogakuin University (JP)
  • Massachusetts Institute of Technology (US)
  • Max Planck Institute for Extraterrestrial Physics (DE)
  • University of Waterloo (CA)
  • Columbia University (US)
Corresponding author
Johnson, Michael D.
ORCID
Venue
The Astrophysical Journal
Publisher
American Astronomical Society
Published
2018-09-27
Volume
865
Issue
2
Pages
104
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
DOI
10.3847/1538-4357/aadcff
OpenAlex
W2889248467
Cited by
105
References
90
Citations by year
2026: 8 · 2025: 9 · 2024: 13 · 2023: 12 · 2022: 22 · 2021: 10 · 2020: 9 · 2019: 19 · 2018: 3
FWCI
5.50
Type
journal article
Language
en
Open access
Licence
Locations
  • The Astrophysical Journal (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • Research Explorer (The University of Manchester) (submittedVersion, other-oa)
  • MPG.PuRe (Max Planck Society) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • National Science Foundation (1440254, 1312651, 1716536)
  • John Templeton Foundation
  • Gordon and Betty Moore Foundation (GBMF5278, AST-1440254)
  • Harvard University
  • Swinburne University of Technology
  • Science and Technology Facilities Council (ST/P000649/1)
  • Japan Society for the Promotion of Science (18K03656)
  • Russian Academy of Sciences
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysical Phenomena and Observations
  • Physical Sciences › Physics and Astronomy › Nuclear and High Energy Physics › Astrophysics and Cosmic Phenomena
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Radio Astronomy Observations and Technology
Keywords
Sgr A*, Galactic center supermassive black hole, radio wave scattering, refractive scattering, interstellar turbulence, density fluctuations, ion Larmor radius, wavelength scaling

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