Astrophysical Jets
Robert Laing (ESO)
Galactic black
-
hole
binary system
Gamma
-
ray burst
Young
stellar
object
Jets are everywhere
Jets in Active Galaxies
… with an emphasis on the nearby
Well
-
collimated, bulk relativistic
flows with
Γ
> 5
Powered by accretion onto black
holes M
10
6
-
10
10
M
SUN
Powers can be as high as 10
41
W
Major effects on galaxy formation
and cluster evolution
Efficient accelerators: electrons
10
14
eV; ? protons >10
20
eV
Jets in radio galaxies
–
up to Mpc scales
FRI
–
low power
Deceleration
Morphological
Classification
Correlates with
radio luminosity
FRII
–
high power
Relativistic and
supersonic until
hot
-
spots
Key topics
Where are the emission sites? What are the radiation
mechanisms?
Jet velocity fields
Effects on galaxy formation and cluster evolution
Composition, power thrust
Formation and collimation mechanism
Emission from jets: broad
-
band and on
many scales
Radio
-
TeV Gamma ray
Synchrotron and inverse
Compton
→
broad
electron energy
distribution + B
Protons?
Auger
Cen A
-
X
-
ray synchrotron
Relativistic effects in jets
Energy spectrum
Doppler boosting
Doppler factor
Jet/counter
-
jet ratio
Aberration
v
app
= 30c
Superluminal
motion
Blazars (
θ
0) are bright,
and rapidly
-
varying
Low
-
power radio galaxies are
side
-
on TeV blazars
M87 TeV
-
core or HST
-
1
Look for correlated variability with both core and HST
-
1
Jet velocity fields
Limb
-
brightening and slow
component speeds: gradual
acceleration or fast spine + slow
shear layer?
Kovalev et al.
2007
Acceleration
→ deceleration?
NGC315
Cotton et al. 1999
RL et al. 2006
Hardcastle et al.
2003
Tingay et al.
TeV results require very high
Γ
-
where are jets
accelerated?
Velocity fields on large scales
VLA data
θ
= 58
o
Model
Velocity
β
= v/c: deceleration and
transverse gradients
3C 31
B2 0326+39
NGC 315 3C296
shock
380 kpc
Hydra A
Wise et al. 07
10
61
erg
Environmental Impact
Radio: Lane et al. 04/Taylor
Low Radio Frequency Traces Energy
74 MHz
Wise et al. 07
Feedback from
jets halts cooling
in cores of galaxy
clusters
Quenching of star
formation
→ major
influence on galaxy
formation
(“downsizing”)
Composition?
Electromagnetic
Leptonic (pair plasma)
-
not near black hole
Hadronic (electron
-
proton plasma;
relativistic protons?
)
Composition must change along the jet.
EM → particles
Entrainment of external medium
Faraday rotation?
Bulk Comptonization
Mass, energy, momentum budget
Sunyaev
-
Zeldovich Effect and Radio
Lobe Composition
Pfrommer, Ensslin & Sarazin (2005)
Perseus cluster
(NGC1275/3C84)
Contours: radio
Colour: X
-
ray
Extra pressure
component
Simulation of ALMA
observation of SZ
decrement
in Perseus cluster
Bubble profiles
for different lobe
compositions
Pressure and density
3C31 0326+39 3C296
Mach number and entrainment rate
Stars
Jets must be very light: consistent with electron
-
positron plasma
Power estimates from cavities
Krichbaum et al.
2006
174 R
s
Limits on collimation from mm VLBI
Jet base 70 x 20 R
S
M87
86GHz
Magnetic collimation?
Coming shortly .... we hope
LWA, eLOFAR
mm
VLBI
ALMA
GLAST
VSOP
-
2
EVLA
eMERLIN
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