Multi- emission from large-scale jets

Fabrizio Tavecchio

INAF – Osservatorio Astronomico di Brera

Outline

Introduction

X-rays from radiogalaxies: synchrotron fromHE electrons

X-ray jets in QSO: the IC/CMB model

Recent observations

Criticisms, alternatives

Almost every galaxy hosts a BHAlmost every galaxy hosts a BH

99 % are silent99 % are silent

1 % are active1 % are active

0.1% have jets0.1% have jets

Cygnus A

Relativistic jets: channels transporting

MassMassMomentumMomentum

EnergyEnergy

from the central BH to the IGM

core

Hot spots

lobes

The unification scheme:

radiogalaxy, RL QSOsblazar

Jets: from the BH to large scale

Resolved X-ray jet

Blazar emission region

Accretion region

VLBI region

X-rays: a new window on old problems

Acceleration and collimation

Power, composition

Particle acceleration

…

1127-145 Siemiginowska et al. 2001 PKS 0637-752 Chartas et al. 2000

Cen A Hardcastle et al. 2003

Pic A Wilson et al. 2000

Producing X-rays in large-scale jets

Powerful (aligned) QSOs

IC/CMBTavecchio et al. 2000Celotti et al. 2001

Synchrotron SSC thermal

Schwartz et al. 2000

very en

ergeti

c elec

trons

Radiogalaxies

FRIs: Synchrotron e.g Worrall et al. 2001, 2002

FRIIs: Synch? SSC? e.g Wilson et al. 2001

Pesce et al. 2001

3C371: a synchrotron jet

Knot B

Knot A

e~107

X-rays

radio optical

M87M87

Very high-energy electrons (e~107) injected in-situ within the jet (shocks? reconnection?)

Radiogalaxies (FRI):Radiogalaxies (FRI):

Powerful QSOs

Synchrotron

IC/CMB

at >100 kpc

Amplification of the CMB energy densityAmplification of the CMB energy density

=10

Photons will appear more concentrated in time and withPhotons will appear more concentrated in time and with

an energyan energy

U’~U U’~U 22

=10L’=1

L=160,000

L=10-4 L=3x10-3

Amplification of the emission

= [= [(1-(1- cos cos )])]-1-1

Parameter space

Equipartition(radio)

IC with CMB (radio and X-rays)

small small ~5 deg~5 deg

~10~10

~10~10

A Chandra-HST survey of jets

17 “radio selected” jets

10 with X-rays (59%)

10 with optical

Sambruna et al. 2001Sambruna et al. 2004

IC/CMB knotsIC/CMB knots

Deep imagesDeep images1136-1351150+497

Synchrotron to Compton transition?Synchrotron to Compton transition?

Speed and power The model allows us to constrain the physical parameters of jets at kpc scale

~3-10 P~1047 -1048 erg/sSupported by recent numerical simulations (Scheck et al. 2002), but see Wardle & Aaron 1997

Fast spine? (Chiaberge et al. 2000; Celotti et al. 2001)

Problems, criticisms, alternatives

Cooling: why X-ray knots?

Large power requirements (~1048 erg/s)

Close alignement (small prob.)

Clumps in jets?

Problem: the X-ray emitting electrons cannot coolcannot cool inside the knot

even including adiabatic losses!

Tavecchio, Ghisellini & Celotti 2003

A possible solution

Several compact regions overpressured with respect to the external

plasma (instabilities, clouds, entrained material, reconnection sites)

Consequence: expected variability in knots (~month)

expansion

very efficient adiabatic losses

New evidences:New evidences:

Several knots in M87 are variable! (Harris et al. 2003)

Cen A shows compact X-ray/radio knotsCen A shows compact X-ray/radio knots(Hardcastle et al. 2003)(Hardcastle et al. 2003)

Synchrotron from complex electrondistributions:

Alternatives to the IC/CMB:

Dermer & Atoyan 2002Dermer & Atoyan 2002

~107 - 108

cooled electrons uncooled electrons

From cooling…

…or from acceleration

Multiple shocks or turbulence (Stawarz et al. 2004):

Marcovith & Kirk 1999

Synchrotron from another electron component or from HE protons…

Aharonian 2002

Secondary electrons could be produced throughp- or p-p

inefficient, Urad quite small

a density of ~1 part/cm3 is necessary

Aharonian 2002Aharonian 2002

Summary

The IC/CMB model works well for powerful jets in QSO

Deep pointings reveal synchrotron to IC transition along the jet

Radiogalaxies: a unique synchrotron component from Radiogalaxies: a unique synchrotron component from radio to X-rays – acceleration mechanism?radio to X-rays – acceleration mechanism?

BUT: problems with low E electrons: clumps?

More observations and exploration of alternatives…More observations and exploration of alternatives…

From subpc to kpc-scaleBlazars and Chandra: physical quantities at (very) different scales!

Example: 1510-089 (z=0.361)

B=2G; R=3x10 cm16

B=0.6x10 G; R=2x10 cm-5 22

Problems, criticisms, alternatives

Cooling: how to produce X-ray knots?

Large power requirements (~1048 erg/s)

Close alignement (small prob.)

Global behaviour (but see G&K 2003)

{

Layer and spineLayer and spine

M87M87

PKS1127-145 Siemiginowska et al. 2002

Offsets?Offsets?

Evidences for small angles from superluminal motions:Evidences for small angles from superluminal motions:

Lore

ntz

facto

r

Angle