Anisotropy in the angular broadening of Sagittarius A* at the Galactic center

Farhad Yusef-Zadeh*, William Cotton, Mark Wardle, Fulvio Melia, Douglas A. Roberts

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


We present the results of a λ = 20 cm VLA2 observation of the compact Galactic center radio source Sgr A*. The scatter-broadened image is elongated in the east-west direction, with an axial ratio of 0.56 ± 0.22 and a position angle of 82° ± 1°.8. A similar shape and orientation has been found previously at shorter wave-lengths using VLBI and VLBA. Both the major and minor axes follow the λ2 law appropriate for scattering by turbulence in the intervening medium. We argue that the scattering occurs in thin ionized surface layers of molecular clouds lying in the central 100 pc of the Galaxy. The ionized regions are characterized by electron densities of 104 cm-3 and milligauss magnetic field strengths, and are responsible for the diffuse free-free emission and the Faraday rotation in the region.

Original languageEnglish
Pages (from-to)L63-L66
Number of pages4
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 20 Oct 1994
Externally publishedYes


  • Galaxies: ISM
  • Galaxy: center
  • ISM: individual (Sagittarius A*, IRS 16)


Dive into the research topics of 'Anisotropy in the angular broadening of Sagittarius A* at the Galactic center'. Together they form a unique fingerprint.

Cite this