physics of relativistic jets
DESCRIPTION
Physics of Relativistic Jets. Jun KATAOKA (Tokyo Tech, JAPAN). Outline. Shock Physics in Relativistic Jets. Jets in Gal/ext-gal objects. Shock acceleration in general. Learning from AGN jets (“blazars” vs “Radio Gal”). Acceleration in sub-pc jets. Jet Structure in large-scale jets. - PowerPoint PPT PresentationTRANSCRIPT
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?