How to hide large-scale outflows: Size constraints on the jets of Sgr A

Abstract

Despite significant strides made towards understanding accretion, outflow and emission processes in the Galactic Centre supermassive black hole Sagittarius A*, the presence of jets has been neither rejected nor proven. We investigate here whether the combined spectral and morphological properties of the source at radio through near-infrared wavelengths are consistent with the predictions for inhomogeneous jets. In particular, we construct images of jets at a wavelength of 7 mm based on models that are consistent with the spectrum of Sgr A*. We then compare these models through closure quantities with data obtained from the Very Long Baseline Array at 7 mm. We find that the best-fitting jet models give comparable or better fits than the best-fitting Gaussian models for the intrinsic source found in previous analyses. The best-fitting jet models are bipolar, are highly inclined to the line of sight (θ ≳ 75°), may favour a position angle on the sky of 105°, and have compact bases with sizes of a few gravitational radii. © 2007 RAS.