Dual-frequency VLBI study of Centaurus A on sub-parsec scales ( C. Müller et al.)

Vol. 530In section 1. Letters

Dual-frequency VLBI study of Centaurus A on sub-parsec scales. The highest-resolution view of an extragalactic jet

by C. Müller, M. Kadler, R. Ojha, et al., A&A 530, L11


Centaurus A, the closest active galactic nucleus, reveals a spectacular radio jet and a counterjet. VLBI observations of this jet at 8.4 GHz and 22.3 GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, and South Africa have just provided the first dual-frequency images of the system, together with the resulting spectral index map. The angular resolution obtained is 0.4 mas × 0.7 mas, corresponding to a linear scale of less than 0.013 pc, the highest resolution VLBI image of Cen A. The image reveals bright knots in the jet, with a flatter index, which could be the source of the recently detected γ-rays from the core region by Fermi/LAT.