JETS

1
JETS

• How are jets observed?
• 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
lobe
hot spot
nucleus
3
CYGNUS A - VLA, 6cm
4
CYGNUS A - VLA, 6cm
undisturbed intergalactic gas
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 F. Owen (NRAO), J. Biretta
(STScI), J. Eilek (NMIMT) 1999
Jet already exists at
www.nrao.edu/fowen/M87.html
9
M87 - 3 billion solar masses
10
M87s RADIO HALO
www.nrao.edu/fowen/M87.html
11
M87s RADIO HALO
www.nrao.edu/fowen/M87.html
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 CATCHRELATIVISTIC MOTION

• Suppose source emits flashes 1 day apart, while
  moving toward you at

14
EXPLANATION OFSUPERLUMINAL MOTION

• Consider continuously glowing blob, moving almost
  directly toward you at

Actual dist. traveled 0.8 lt-day Apparent
travel time (1- 0.8 cos?) day Sideways dist 0.8
sin? Apparent sideways speed 0.8 sin? / (1-
0.8 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?

16
(No Transcript)