Acceleration and Energy Transport in the AGN jets: from sub-pc to kpc scale

　　　　 Jun Kataoka Tokyo Institute of Technology

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- Acceleration site in the universe - Acceleration [1] : inner jets <sub-pc jet>- Acceleration [2] : outer jets <kpc jet>- Energy transport along the jet- Conclusion K et al , 2001, ApJ, 560, 659

, 2002, MNRAS, 336, 932 , 2003a, A&A, 399, 91

, 2003b, A&A, 410, 833

Cosmic-ray spectrum

E < 1015.5 eV- Galactic origin - SNRs ?

E > 1015.5 eV - Extragalactic origin ?

Emax [TeV] ~ 103 R [pc] B [G] (R: system size, B: magnetic field)

Bamba et al. 2003

- Evidence for acceleration up to 10-100 TeV

Larmor-radius : RL = eBmc2

< system size

Acceleration sites in the universe

Acceleration in AGNs?

- typical power : 1044 [erg/s/AGN] - number density : 10 -7 [AGN/Mpc3]

“Almost equal to the energy density of CRs above the knee” (Gaisser 2000)

AGN (inner)

White Dwarfs

Neutron Stars

SUNSPOTS

Gal disc & halo

Interpl. Space SNR

AGN (outer)Galaxyclusters

Extra-galactic site: AGN (sub-pc), AGN (kpc, HS, lobes), galaxy clusters, and -ray bursts…

Hillas 1984

1km 1pc 1Mpc

size : R

1012 G

106 G

1 G

1 G

mag

net

ic f

ield

: B

Magnetic stars

AGN with relativistic jet

- Plasma outflows called “jet” 　 have been observed　 (about 10 % of AGN)

- Super-luminal motions imply jets are highly relativistic (~10 or ~ 0.994)

- Jet size ranges from ~0.1 pc to more than 1 Mpc

ex. 3C46 (1.4 GHz)

core (AGN) + inner jet

knot

lobe

hot spot

Inner-jet : “Blazar”-region

- Rapid time-variability as short as 1 day D ~ ctvar

BLK ~ 1017 cm 　 (sub-pc)

- Spectral Energy Distribution from radio to TeV -ray acceleration up to 1012 eV

TeV

RXTE (8-15keV)

ASCA(0.5-7keV)

EUVE

SAX

1 day

radi

o

optic

alX-

ray

GeV

-

TeV-

Mrk 421

Mrk 421

synchrotronInverse Compton

Takahashi et al. 2000

Acceleration mechanism in sub-pc jet

- Central black-hole mass: 109 M

- Central engine intermittently expels blobs of material, which collide at D ~ BLK

2 Rg ~ 1017-18 [cm]

- Physical parameters from temporal/spectral studies : B~ 0.1 G, R~0.01pc, max~ 106

BLRcloud

BLRcloud

1017-18 cm (sub-pc)

X-ray/-ray

“Theoretical limit” in the sub-pc jet

Max Energy max ?

sync ~ 2.5x1021 sh2

10 MeV (indep. on B)

tacc = 20c

3vs2

, where RL

tcool = 3 mec

4(uB + usoft)T

(RL : Larmor radius)

if “tcool= tacc at max” & “synchrotron dominated”

max ~ 1.4x108 101/2B0.1

-1/2 -1/2 sh

max mec2 ~ 70 TeV

Extreme Blazars- Detectable with CANGAROO?

- High-freq blazars have low luminosities : sync∝Lsync

-1.5 　

Kubo et al. 1998

- Assuming z = 0.03 (c.f., Mrk 421 & 501),

we expect F(@1TeV) ~ 10-13 ph/cm2/s … still difficult to detect ?

- High-freq blazars also have low Comp/sync ratio: LC/Ls 1 　

Mrk 501 flare

Ghisellini 1998

Outer-jet: “kpc-region”

- Many AGNs show flat radio-optical spectra: evidence for “accelerated” particles

- To resolve kpc-jet in z=0.1 AGN, < 0.5’’ is necessary

- Chandra has resolved >20 of X-ray jets in AGNs

pictor A

PKS0637-752 3C273 PKS1127-145

Cen A Cyg A

M87

Ex 1: Hotspot in 3C 303

- 15 ksec observation by Chandra in March 2001

- “X-ray hotspot” was detected at 9.6 level (92 photons)

- hotspot and bgd-QSO (z=1.6) were clearly resolved

Radio (VLA; 1.5 GHz) X-ray (Chandra: 0.4-8 keV)

knots Hot Spot

bgdQSO

K et al. 2003a

nucleus

36 kpc(projected)

Hot Spot

Emission mechanism of 3C 303 hotspot

- X-ray flux is well below the rad-to-opt continuum

- Synchrotron self-Compton (SSC) dominates: usync ~ 2×10 -12 [erg/cm3] ~ 3x uCMB

LX

uB<

usync + uCMB

Lsync

B < 28 G

Synchrotron peak at 1014 Hz < max

max > 2x106

Best fitting parameter: B = 4.3G, max =1.4x107

synchrotron

SSC

ERC (CMB Compton)

Inv Compton origin

Ex 2: X-ray jet and lobes in 3C 15

- FRII radio galaxy at z = 0.0730 (1” = 1.25 kpc)

- “optical/X-ray synchrotron jet” has been detected

- Knot-C is the brightest (0.5 kpc FWHM ) in the X-ray band

- “X-ray lobes” are clearly detected

lobes

Jet ProfileX-ray (Chandra: 0.4-8 keV)

1’

Kataoka et al. 2003b

K et al.2003b

Broad-band spectrum of jet and lobes

Frequency Hz

Fe

rg/c

m2 /

s

Frequency Hz

kpc-jet(knot-C)

Radio lobes

- magnetic field B : 240 G 4 G

- Max Energy max : 2×107 1×106? - Ratio Ue / UB : ~ 1? ~2×103 - Jet power Ljet : 3×1044 erg/s

- Lobe ene Elobe : 9×1059 erg

kpc-jet lobes

Fueling time of the jet ?

tfuel ~ Elobe/Ljet ~ 8×107 yrs

Consistent with the “source age” of the radio lobes: tsrc ~ 2.1×107 (0.01 c / vexp) yrs

Thermal/non-thermal pressure balance?

- Plobe, thermal ~ 1.9 ne,th kT = 8.1×10-12 erg/cm3

- Plobe, non-th ~ 1/3 (Ue + UB) = 3.8×10-10 erg/cm3

But, how to confine non-thermal electrons?

Plobe, thermal < Plobe,non-th

More samples are awaited!

Ex.3 M87: Ultra particle accelerator ?

M87 jet

Marshall et al. 2003

sync ~ 1.2x106 B max2 ~ 1018 [Hz]

Assuming ue = uB, we expect B ~ 100 G

max ~ 108 B100 -1/2

( This would be larger if ue > uB )

Kpc-scale Jets: a Cosmic-ray booster?

Knot

Hot spot

- kpc-jet

TeV blazar

Low freqBL Lac

- sub-pc-jet

×

QuasarHostedBlazar

Max

ele

ctro

n E

Magnetic field B

1G 1mG 1G

5 GeV

1 TeV

500 TeV

3C153C303

sub-pc jet(Blazar AGNs)

kpc jet(knot/hot-spots)M87

K et al. 2004, in prep

“Blazar Heart” in Radio Galaxies

blazars

BLRG

Radio Gal.

BH

blazar heart in “Cen-A”

Chiaberge et al. 2001

FR-I 　⇔　 BL LacsFR-II ⇔ OVV quasar

- Blazar core in Radio gal should be much fainter, since ∝

- SED can be fit by “blazar parameters”, except for beaming factor of ~ 2

Sub-pc jet & nucleus of 3C 273

- Typical blazar (super-luminal motion, rapid variability…), but “jet” and “acc. disk vicinity” are both visible. - Furthermore, kpc-jet is also resolved by HST & Chandra

Beamed-synchrotron

BeamedSSCor ERC

Non-beamed blue bump

HE

SED of sub-pc jet (3C 273)

K et al. 2002

Kpc-jet of 3C273 (by Chandra)

- Kpc-jet luminosity is ~ 10- 3 of sub-pc jet

~ 50 kpc

(projected)

A

B

C

D

Sambruna et al. 2001

- X-rays are likely due to the inv. Comp of CMB photons

Sub-pc vs kpc jet power

Lkin (Jet power)

N (no. density)

sub-pc 10-kpc

max (Max ene)

R (region size) 0.01 pc 1500 pc

1.0×105 /cm3

B (Magnetic field)

8.1×10-3 /cm3

1.9×10-6 G0.4 G

2.0×103 6.0×106

4.0×1045 erg/s >1.3×1047 erg/s

- about 100 times of “visible” kinetic energy may be hidden at the bottom of the jet (sub-pc).

Why Lkin, kpc > Lkin, sub-pc ?

- In sub-pc, only less than 1% of electrons are picked up into shock acc. process (internal shock : see Tanihata et al. 2003)

1 10 102 104 105 106

Ethermal1

10-2

10-4

10-6

10-8

Electron Lorentz factor

Ele

ctro

n N

o d

en

sity

103

E non-thermal

- In kpc, most of electrons are accelerated efficiently when colliding with ISM (external shock : see Dermer 1998)

Very similar to the relation Between GRB (int shock) and afterglows (ext shock)

Conclusion

Not only sub-pc scale jet, but also kpc-scale jets are one of the most powerful accelerators in the universe.

- Some radio galaxies actually accelerate particles up to Emax > 10 ~ 100 TeV

Only <1 % of bulk kinetic energy may be released in sub-pc, whereas most of its power released in kpc.

- Different shock acceleration at work between sub-pc and kpc. e.g., “internal shock” and “external shock” ?

- There may be hidden “blazars” of Emax ~ 70 TeV (acc limit)

- Need more sample, but apparently similar to GRB