X-rays from the jet in 3C 273: Clues from the radio–optical spectra

Abstract

Using new deep VLA and HST observations of the large-scale jet in 3C 273 matched to 0$\farcs$3 resolution, we have detected excess near-ultraviolet emission ($\lambda\,300\mbox{${\rm\,nm}$}$) above a synchrotron cutoff spectrum accounting for the emission from radio through optical ($\lambda\lambda 3.6\mbox{${\rm\, cm}$}$–$620\mbox{${\rm\,nm}$}$). This necessitates a two-component model for the emission. The radio–optical–X-ray spectral energy distributions suggest a common origin for the UV excess and the X-rays from the jet.