Published in The Astronomy and Astrophysics Review, Vol. 17, p. 1-46, 2009.
astro-ph/0812.3401

For a PDF version of the article, click here.

THE X-RAY JETS OF ACTIVE GALAXIES

D.M. Worrall


Dept of Physics, University of Bristol, Tyndall Ave, Bristol BS8 1TL, UK
d.worrall@bristol.ac.uk


Abstract. Jet physics is again flourishing as a result of Chandra's ability to resolve high-energy emission from the radio-emitting structures of active galaxies and separate it from the X-ray-emitting thermal environments of the jets. These enhanced capabilities have coincided with an increasing interest in the link between the growth of super-massive black holes and galaxies, and an appreciation of the likely importance of jets in feedback processes. I review the progress that has been made using Chandra and XMM-Newton observations of jets and the medium in which they propagate, addressing several important questions, including: Are the radio structures in a state of minimum energy? Do powerful large-scale jets have fast spinal speeds? What keeps jets collimated? Where and how does particle acceleration occur? What is jet plasma made of? What does X-ray emission tell us about the dynamics and energetics of radio plasma/gas interactions? Is a jet's fate determined by the central engine?


Table of Contents

THE STAGE IS SET
Historical perspective
Radiation processes
Generic classes of jets
Lifetimes and duty cycles

ARE THE RADIO STRUCTURES IN A STATE OF MINIMUM ENERGY?
Calculation of the minimum-energy field
Using X-rays to test minimum energy

DO POWERFUL LARGE-SCALE JETS HAVE FAST SPINAL SPEEDS?
The impetus from PKS 0637-752
The dependence of beamed iC-CMB on beaming factors and redshift
How is the beamed iC-CMB model faring under scrutiny?
Synchrotron emission as an alternative

WHAT KEEPS JETS COLLIMATED?

WHERE AND HOW DOES PARTICLE ACCELERATION OCCUR?
The link with synchrotron X-ray emission
Particle acceleration in knotty structures
Incorporating polarization data

WHAT IS JET PLASMA MADE OF?

WHAT DOES X-RAY EMISSION TELL US ABOUT THE DYNAMICS AND ENERGETICS OF RADIO PLASMA/GAS INTERACTIONS?
Expectations for FRIIs
Dynamics of FRIs in clusters
Centaurus A
The effect of galaxy mergers

IS A JET'S FATE DETERMINED BY THE CENTRAL ENGINE?
An evolutionary cycle?
The rôle played by accretion processes
The rôle of the environment
Information from beamed sources

SUMMARY AND CONCLUDING REMARKS

REFERENCES

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