Astrophysical Jets

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15 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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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