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Galactic jet
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Astronomers study two million light year 'extragalactic afterburner'

Blasting over two million lights years from the centre of a distant galaxy is a supersonic jet of material that looks strikingly similar to the afterburner flow of a fighter jet, except in this case the jet engine is a supermassive black hole and the jet material is moving at nearly the speed of light.
Research published over the weekend in the Astrophysical Journal Letters shows the galaxy-scale jet to have bright and dark regions, similar to the phenomenon in an afterburner exhaust called 'shock diamonds.'

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PKS 0637-752
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Title: HST observations of the quasar PKS 0637-752: equipartition electron-proton jet from the most complete spectral coverage to date
Authors: Kushal T. Mehta, Markos Georganopoulos, Eric S. Perlman, Charles A. Padgett, George Chartas

We present new NICMOS and ACS observations of the quasar jet PKS 0637-752, and we use them, together with existing multiwavelength observations, to produce the most complete spectral coverage of the source to date. We explore the implications of these observations in the context of models for the jet X-ray emission. By relaxing the assumption of equipartition, we undertake an exhaustive study of the parameter space for external Compton off the CMB (EC/CMB) model. We find that the multiwavelength observations exclude a magnetic field dominated jet. Using the method proposed by Georganopoulos et al. (2005) for probing the jet matter content we show that protons are needed for practically all jet configurations, extending a previous application of the method by Uchiyama et al. (2005) that was based on exploring three particular jet configurations. We also show that equipartition is the only configuration that can reproduce the observations and have one proton per radiating lepton. We finally present a rather model - independent argument that the jet has a spine-sheath flow pattern, with the spine being faster and emitting most of the IR-optical-X-ray emission.

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