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

Using new deep VLA and HST observations of the large-scale jet in 3C 273 matched to 0.3 arcsec resolution, we have detected excess near-ultraviolet emission (lambda 300 nm) above a synchrotron cutoff spectrum accounting for the emission from radio through optical (lambda lambda 3.6 cm-620 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.