Spitzer Observations of Centaurus A: Synchrotron Emission in the Infrared

We present measurements obtained with the Spitzer Space Telescope in five bands from 3.6–24μm of the northern inner radio lobe of Centaurus A, the nearest powerful radio galaxy. We show that this emission is synchrotron in origin. Comparison with ultraviolet observations from GALEX shows that diffuse ultraviolet emission exists in a smaller region than the infrared but also coinciding with the radio jet. It is plausible that synchrotron emission extends to ultraviolet wavelengths without a break, however further data are required to confirm this. Subject headings: galaxies: active, individual(Centaurus A) — radio continuum: galaxies — radiation mechanisms: non-thermal