VLBA Imaging of NGC 4261: Symmetric Parsec-scale Jets and the Inner Accretion Region

Abstract

Dual frequency VLBA observations of the nucleus of NGC 4261 (3C270) reveal highly symmetric radio structures at both 1.6 and 8.4 GHz. Analysis of these images shows that the central 10 pc of this source is not significantly affected by free-free absorption, even though the nucleus of the galaxy is known to contain a nearly edge-on disk of gas and dust. The lack of detectable absorption implies that the density of ionized gas in the central 10 pc is less than (is similar to) 10³ cm ^-3, assuming a temperature of (is similar to) 10⁴K.