The radio spectrum of the compact source at the galactic center

Abstract

view Abstract Citations (13) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The radio spectrum of the compact source at the galactic center. Brown, R. L. ; Lo, K. Y. ; Johnston, K. J. Abstract Observations of the compact radio source at the Galactic center obtained at 11.1 and 3.7 cm with the Green Bank 35-km radio-link interferometer and at 6, 2, and 1.3 cm with the VLA reveal that the flux density of the source increases with increasing frequency for frequencies less than or about equal to 25 GHz. This result, taken in conjunction with recent VLBI observations which show Sgr A to be no more than 0.001 arcsec (10 AU), requires either that the magnetic field in the source is very high, greater than 200 G, or that the true source size is significantly smaller than the VLBI limits, about 2 AU, and hence that the energy density in the source is very large, greater than 15 erg/cu cm. An alternative to this description is provided by the similarity of the radio properties of Sgr A to those of Galactic radio stars in which the opacity at centimeter wavelengths is provided by free-free absorption. If this latter interpretation is applicable, the compact radio source at the Galactic center is likely to be associated with one member of a multiple-star system. Publication: The Astronomical Journal Pub Date: December 1978 DOI: 10.1086/112368 Bibcode: 1978AJ.....83.1594B Keywords: Galactic Nuclei; Radiant Flux Density; Radio Astronomy; Radio Sources (Astronomy); Radio Spectra; Milky Way Galaxy; Radio Interferometers; Radio Scattering; Radio Stars; Stellar Magnetic Fields; Synchrotron Radiation; Very Long Base Interferometry; Astrophysics; Flux Densities:Galactic Center; Galactic Center:Radio Radiation full text sources ADS | data products SIMBAD (8)