Inverse Compton X-ray signature of AGN feedback. (arXiv:1306.2636v1 [astro-ph.GA])

Inverse Compton X-ray signature of AGN feedback. (arXiv:1306.2636v1 [astro-ph.GA]):
Bright AGN frequently show ultra-fast outflows (UFOs) with outflow velocities
vout ! 0.1c. These outflows may be the source of AGN feedback on their host
galaxies sought by galaxy formation modellers. The exact effect of the outflows
on the ambient galaxy gas strongly depends on whether the shocked UFOs cool
rapidly or not. This in turn depends on whether the shocked electrons share the
same temperature as ions (one temperature regime; 1T) or decouple (2T), as has
been recently suggested. Here we calculate the Inverse Compton spectrum emitted
by such shocks, finding a broad feature potentially detectable either in
mid-to-high energy X-rays (1T case) or only in the soft X-rays (2T). We argue
that current observations of AGN do not seem to show evidence for the 1T
component, while the limits on the 2T emission are far weaker. This suggests
that UFOs are in the energy-driven regime outside the central few pc, and must
pump considerable amounts of not only momentum but also energy into the ambient
gas. We encourage X-ray observers to look for the Inverse Compton components
calculated here in order to constrain AGN feedback models further.