1. JETS How are jets observed? Where do they come from?
How do they interact with their surroundings?
The radiation from jets
Where do they come from?
Tracing them to their source
How are they made?
Magnetic propulsion
Energy source? Accretion or BH spin?

2. RADIO GALAXIES Cygnus A lobe hot spot nucleus
VLA, 21-cm radio emission
RADIO GALAXIES
lobe
hot spot
nucleus

3. CYGNUS A - VLA, 6cm

4. CYGNUS A - VLA, 6cm undisturbed intergalactic gas splash point
“cocoon” (shocked
jet gas)
splash point
backflow
bow shock

5. Abell 4059 (Chandra image)

6. How do we know the jets are streams of gas? 3C 449
They produce of kind of “skywriting” when interacting with background
NGC 1265
a “radio trail”

7. SS 433 An X-ray binary, not an AGN
Only case where Doppler shifts give jet speed: 0.26c
Precesses like a top every 164 days
Not known whether neutron star or BH

8. M87 RADIO MONTAGE Jet already exists at
F. Owen (NRAO), J. Biretta (STScI), J. Eilek (NMIMT) 1999
Jet already exists at

9. M87 - 3 billion solar masses

10. M87’s RADIO HALO

11. M87’s RADIO HALO

12. ONE-SIDEDNESS
Many jets appear “one-sided” but lobes are symmetric: Why?
Clues:
“Jet side” is always side coming toward us (how do we know?)
Superluminal motion
Rapid variability
ACCEPTED EXPLANATION: RELATIVISTIC MOTION
One-sidedness due to beaming (aberration + Doppler) effect

13. THE REAL CATCH: RELATIVISTIC MOTION
Suppose source emits flashes 1 day apart, while moving toward you at
0.8c
Flash 1
1 lt-day
0.8 lt-day
Flash 2
0.2 lt-day
Day 0
Day 1
Flashes emitted 1 day
apart, received
0.2 days apart.

14. EXPLANATION OF SUPERLUMINAL MOTION
Consider continuously glowing blob, moving almost directly toward you at
Day 1 
0.8 sin
0.8 cos
Actual dist. traveled: 0.8 lt-day
Apparent travel time: ( cos) day
Sideways dist: 0.8 sin
Apparent sideways speed:
0.8 sin / ( cos) c
0.8c
0.8 lt-day
Day 0

15. HOW ARE JETS MADE? Hypothesis: Jet axis = rotation axis
What force “pushes” jets?
Gravity? Wrong direction
Centrifugal force?
Gas or radiation pressure?
Magnetic forces?
Energy source?
Accretion? Jet launched from disk
Black hole spin? BH behaves like flywheel
Why are they focused to narrow streams?