Physics of Relativistic Jets

Jun KATAOKA (Tokyo Tech, JAPAN)

Outline Shock Physics in Relativistic Jets

Learning from AGN jets (“blazars” vs “Radio Gal”)

Comments on GRB jets (vs. AGN)

Jets in Gal/ext-gal objects

Jet Structure in large-scale jets.

Warning signal on the standard model. Acceleration in small-scale B-field.

Shock acceleration in general

Acceleration in sub-pc jets.

Galactic/Extragalactic Jets

Relativistic jets – exciting, powerful, but least understood phenomena.

QSO AGN GRB

A number of compact objects (Gal/ext-gal) have jets with various sizes. size : 1AU ~ 1Mpc, power : 1040~ 1052erg/s, jet : a few ~ 1000 similarities – underlying physics are the same!

Shocks in jets are most promising site of particle acceleration.

Why AGN Jets? scale size: Rg ~ 1013 cm ~ 1AU.

total power : Ptot ~ 1044-48 erg/s Etot ~ 1058-60 erg.

# density : n ~ 10-7 AGN/Mpc3

jet launching site (~30 Rg)

sufficient for CR acceleration.

(jet structre, opening angle etc … with the low-E VLBI observations)

Junor+ 99

Strong B-fieldfor launching

“bulk” motion of jet plasma

“random” motion & acceleration

non-thermalradiation

What makes the relativistic outflow?What makes the relativistic outflow?

~ 30 Rg

Shock Acceleration in Jets

c = 1.6 x 104 T82 nth,-4

-1kpc

(T = 108 T8 [K], nth = 10-4 nth,-4 [cm-3])

rL = 1.2 x 10-13 T8-1/2 B-6

-1 kpc(B = 10-6 B-6 [G])

B-field

particle

vup vdown

Coulomb collision

Gyro radius

Collisionless shock in AGN jets.

Shock acceleration process: En = Eo (1)n ~ (1+ 4/3)n N= -s, where s ~ 2.

shock in AGN : rL ~10-14 kpc << R~ kpc << c~104 kpc

c ~10-15 cm << R~103 cm << rL ~106 cm c.f., ground exp :

...But where B comes from?, really 1...But where B comes from?, really 1stst0rder ? What is the shock!0rder ? What is the shock!

Standard Picture

min

max

tacc = (20c/3vs2)rg ∝ Ee tcool = [ Ee/ (dEe/dt) ] ∝ Ee

-1

We can derive B-field strength by Sync/IC ratio as

For a given Lsync, LIC B-2 B, max , size etc…

maxmin

N()

non-thermalnon-thermal

thermalthermal SyncSync

ICIClow B

radio X-ray -ray

Em

issi

vity

high B

What fraction of “seed particles” injected?

How efficient the “accelerator” is ?

“Non-thermal” emission

Learning from AGN Jets

AGN Jet: review

B.H sub-pc kpc ~ Mpc

low power (FRI, BL Lac)low power (FRI, BL Lac)

high power (FRII, QSO)high power (FRII, QSO)

Blazars(small )

radio galaxies(large )

Viewing angle is a key to identify various classes in AGNs.

Blazars’ emission come from the most inner part of the jet, via the internal-shock in sub-pc jet.

Large scale jets in powerful radio galaxies (FR II/QSO) extend to Mpc scale: external-shock?

Measurement of jet speed (VLBI) : jet > (app +1)1/2

Multi-band campaigns organized by ASCA,SAX,RXTEASCA,SAX,RXTE … … - confirm “double peak” structure over two decades in freq!

B ~ 0.1 G, jet ~ 10, ue ~ 10 uB

Rapid time variability : R ~ ctvar

Multiband SED of Blazars (sub-pc jet)

D ~ Rjet~ sub-pc

X-ray GeV TeV optical

ERC

SSC

LE HELE peak(synchrotron)

HE peak(Inv. Comp)

Takahashi+ 96,Kubo+ 98 Kataoka+ 99-02

Search for “Extreme Blazars”

Clear correlation between luminosity and peak freq : sync∝Lsync-1.5 　

max ~ 1.4x108 101/2B0.1

-1/2 -1/2 sh max ~ 10 MeV

Significant fraction are still hidden - only “visible” in hard X-rays! .

“Extreme” particle accelerators - though very faint (5x10-13 erg/cm2/s @50keV) NeXT/XEUS can easily detect “dark accelerators”.

luminosity

Max

E

1TeV

1GeV10mJy

XEUS Ghisellini+ 98, Kubo+98

ExtremeExtremeBlazarsBlazars

Distant Blazars with XEUS/NeXT ? Swift J0746

(z = 2.98)

“MeV-peaked” blazars at z 10 can be detected (if exists!).

min can be observed in X-rays for distant QSOs. - kinetic power of jet? - jet content (e-e+ or e-p)? Accel. fraction ? (e.g., Kino & Takahara 03)

Cosmological evolution of blazars - relation to SFR? Where the QSOs gone? cosmic X/-ray BGD?

Lo

g

F

Q0836+710(z=2.17)

min =1

310

Sambruna+ 06

If z=10

Large-scale jets in X-rays

Lkin ~ R2 c jet (ue + uB )

Lrad ~ 4R2 c (uB + urad) Lkin

Lrad

BLK

1 1

100

Only ~ 1% of kinetic energy would be converted into radiation in sub-pc jet, consistently with “internal shock” scenario.

Jet interaction, heating, and structure formation in cluster plasma.

Chandra : Wilson+ 00Jet model : Begelman & Cioffi 89

FR II (Cygnus A)

Chandra obs provides direct probe to physics in large-sale jets

Variety of Large Scale FR-II Jets

Jet-knot hotspot lobe

3C219Pictor A3C273

F

F

F

radi

o

X-rayra

dio

X-ray

radi

o

X-r

ay

IC/CMB(ue = uB)

Both hotspots and radio-lobes suggest ue ~ uB, while jet-knots are generally too bright in X-rays.

Double peaks – IC/CMB emission for X-rays?

Need of Doppler boosting for jet-knots: LIC/CMB ∝ 3 ? (Tavecchio+ 00, Sambruna+ 04)

Relativistic Large-scale Jet?

… BUT, enhancement due to beaming is hardly expected in radio galaxies as viewing angle is very large!

If we give up “ue ~ uB” assumption, ue ~ 108 uB required !.

50

10

1 jet = 30

jet = 10

jet = 3

0 30 60 90 [deg]

Bea

min

g f

acto

r

= 10

blazars Radio galaxies

0.1Beaming factor

1 10 100

knothotspotlobe

~ 10 indeed required only for the jet-knots.

Death of boosted IC/CMB scenario?Death of boosted IC/CMB scenario?

Kataoka & Stawarz 05,ApJ

SPITZER

Evidence for “Sync X-ray Jet”

SPITZER obs of 3C273 jet confirms that the optical jet is dominated by the 2nd Sync component, as it strongly polarizes Popt = 15 % (~ Pradio).

A smooth connection between optical and X-rays, suggest X-rays are also Sync (leptonic? hadronic? still under debate!)

Uchiyama,+ 06, also Jester+ 06 3C273

Detection @50 keVDetection @50 keV EEee >10 >1015 15 eV and/or EeV and/or Epp >10 >1018 18 eV!eV!X-ray polarization?X-ray polarization? Evidence for “exsotic” Sync X-ray spectrumEvidence for “exsotic” Sync X-ray spectrum..

Turbulent Acceleration?

Accel. process in layer is quite different!

tesc/tcool ~ 107 (B100G)3 (l100pc)2 -1

where = UB/UT

Ostrowski 00, Stawarz & Ostrowski 02Ostrowski 00, Stawarz & Ostrowski 02

If field is very turbulent ~ 1, electrons “pile-up” as it never escape from the region.

N(

max

ttaccacc~ ~ 33ee

ccccVVAA

22

ttescesc~~ 33LLVVAA

22

ee

cc

~ 5x10~ 5x109 9 8 8 BB-1-1100100VV-2-2

A,8A,8 [s] [s]

~ 6x10~ 6x105 5 88-1-1

BB100100LL22100pc100pc [s] [s]

observed hump in X-rays?

different spectra in spine/layer.

spinespine layerlayer Stratified jet – “spine” + “layer”.

CR

Transverse Profile of Cen-A X-ray JetKataoka+ 06, ApJKataoka+ 06, ApJ

Jetcenter

“double-horn” profile in the transverse direction.

Uniform spectra over the jet, except for jet edges.

tsyn ~ 20 B-3/2 E-1/2 [yr]

100 10keV

Diffuse Jet

0.4-8 keV

Ideal laboratory - “nearest” AGN (dL = 3.4Mpc, 1” = 18 pc).

Acceleration over the jet volumes (NOT exclusive to bright jet-knots!)

Jet profile in hard X-rays provides direct hints of CR accel. !Jet profile in hard X-rays provides direct hints of CR accel. !

1keV

flu

x

X

Position angle25 45

Brief comments onGRB Jets

GRB vs AGN Jets

“Blazar” region lobe, hotspot

The standard model of -ray prompt emission is still rough, but somehow explains afterglow emission well.

10

>100 106 G

0.1 G0.01pc

10-5 pc ~ 0.1

0.1

1052 erg/s

1046 erg/s

GRB (prompt)

AGN (blazar)

Ltot R jet B B, et

10s

1014s

AGN vs GRB: typical parameters:assumption, but GLASTan detect IC of GRBs

GRB spectrum: prediction

Observed GRB spectrum often agree with Sync shock model, BUT…

significant # of GRBs “inhibited”? (death-line problem)

spectral break is too sharp ?

Problems due to low sensitivity of Problems due to low sensitivity of BATSE below 50 keV ?BATSE below 50 keV ?

Inhibited

Spectral Index:

=-2/3

Ebr

Preece+98

HETE-II Observation of GRB020813

Sync self-abs cannot explain < -2/3 spectrum.

Spectral measurement in wide energy band: 2-400 keV

SSA~ 7.3x10^(-6) R13n8 B62/3-2/3

1001000

19-5/3

<< 1

IC model of X-ray production also rejected.

Violation of standard picture, e.g., Violation of standard picture, e.g., B B << 1 ?<< 1 ?

Why so different from AGN jets ? Why so different from AGN jets ?

Sato+ 05

Inhibited

“Jitter” radiation in tangled B-fields B-field is randomly tangled:

deflection << beaming “jitter” radiation

(Landau & Lifshits 75)

Hard spectrum + sharp break

Death line

Death line

jit~ 1010 m

jet ~ 1017-20 [Hz]

Tangled field in GRB jet ? - Rapid expansion! - Not enough time for growth of large-scale, regular fields ?

Medvedev 00

Fjit ∝1 < jit

-(p-1)/2 > jit

1-(p-1)/2

Feedback for the theory of collisionless shock, in general.

Summary

Physics of AGN jets are being much clear thanks to previous ASCA/BeppoSAX/RXTE, but nature of large scale X-ray jets is still open, even after advent of Chandra/XMM.

GRB physics is also still unclear, especially for prompt emission.

Many of jet physics will be deeply probed in NeXT decade.

Important hints on the field and formation of relativistic jets.

Future observations with XEUS/NeXT… and GLAST etcFuture observations with XEUS/NeXT… and GLAST etc will give us a clear answer of “what is the jet?” will give us a clear answer of “what is the jet?”

CR acceleration and what is collisionless shock?