HST Pictures: (a more popular and more detailed draft figure caption is also available)
The narrow emission line region (NLR) of the Seyfert galaxies Mrk 573 and ESO 428-G14. This is
hot gas of several 10.000 K temperature ionized by a "central engine" -
most likely an accreting black hole.
(click on image to get full-scale version)
When adding the radio maps it becomes clear that the "funny"
shapes of the NLR are produced by a hot plasma "jet" consisting of
highly relativistic, synchrotron radiation emitting electrons, only
visible to radio telescopes, and wrestling with the gas in the center of the galaxy.
(click on image to get full-scale version)
Comparing two filters and constructing an excitation map ([OIII]/Halpha) of the
gas, one can see that the highly ionized gas is concentrated in a
fan-shaped geometry (or excitation cone) - thus tracing the beamed
radiation from the black hole in the center
(click on image to get full-scale version)
