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Astrophysics Colloquium

The Fire of the Phoenix: How Cosmic Jets are Born, and Re-Born, into their Final Observed Form
Presented by David Meier
Jet Propulsion Laboratory, California Institute of Technology

Thursday, November 7, 2013
4:00 P.M. in 169-336

While orientation and obscuration effects can explain much of the variation seen in observed AGN properties, there are some differences among AGN populations that appear to need some fundamental astrophysics to explain them. Most notably, these are: (1) radio-loud vs. radio-quiet AGN, (2) high-excitation (Class A) vs. low-excitation (Class B) emission line objects, and (3) the Fanaroff and Riley (FR I & FR II) morphological/radio-power dichotomy. I will touch on each of these, but spend most of the time discussing a new paradigm for the FR I / II division in which a jet's final properties are determined fairly close to the central supermassive black hole (within a few parsecs) in a dramatic and life-changing "recollimation shock". In that shock the supermagnetosonic jet produced by the black hole system is "re-born" into either a transmagnetosonic one (FR I) or a super-sonic one (FR II). Recent theoretical results, as well as observational results on the M87 and BL Lacertae jets, are very compatible with this picture in the FR I case. I also will talk about future work that may further test both this and the FR II case as well. There also are some tantalizing signs that this process may be applicable to other types of jets as well (protostellar, etc.).

SVCP Astrophysics

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