X-ray Synchrotron Spectral Hardenings from Compton and Synchrotron Losses in Extended Chandra Jets

Chandra observations of knots and hot spots in spatially resolved X-ray jets of radio galaxies show that the X-ray fluxes often lie above an extrapolation from the radio-to-optical continuum fluxes. We show that combined synchrotron and Compton losses on a single power-law electron injection function can produce a hardening in the electron spectrum at electron Lorentz factors γ ≈ 2×10/[Γ(1+ z)] due to KN energy losses on the cosmic microwave background radiation. Here Γ is the bulk Lorentz factor of the outflow, and z is the source redshift. This produces a flattening in the spectrum at frequencies & 8× 10δBμG/[Γ(1+ z)] Hz, where BμG is the magnetic field in the comoving plasma frame in units of micro-Gauss and δ is the Doppler factor. A single population of synchrotronemitting electrons may therefore produce the radio-to-X-ray continuum in some radio galaxy knots, such as those in 3C 273. Subject headings: galaxies: active — galaxies: jets — gamma-rays: theory — radiation mechanisms: nonthermal — X-rays: galaxies