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Attilio Ferrari
CIFS Consorzio Interuniversitario per la Fisica Spaziale
Dipartimento di Fisica Generale, Università di Torino
INAF Osservatorio Astronomico di Torino
INFN, Sezione di Torino
RELATIVISTIC JETSRELATIVISTIC JETS
IN ASTROPHYSICSIN ASTROPHYSICSComputer simulations and experimental validationComputer simulations and experimental validation
Plasmas in Astrophysics and in the Laboratory - The Ignitor Challenge
Moscow, 20 - 21 June 2011
Highly nonlinear (relativistic) physics
Huge extension of physical parameters
Scalability
Astrophysical plasmas
Observations
Theoretical plasma physics
Numerical simulations
Laboratory plasma physics
Experiments and validation
GRS
3C279
Superluminal motions & Doppler boosting jet/counter-jet(Cohen et al. 1971, Biretta et al. 1999, Mirabel et al 1992)
Astrophysical Evidence of
Relativistic Jets
Jets and VHE Sources Variabilities
• Blazars, energetics (Oke & Gunn 1974)
• VHE emission and rapid variabilities correlated with Xrays and radio emission– Mkn 421 (AGILE, Donnarumma et al. 2009)– M87 (FERMI, Acciari et al. 2009)
• GRBs, energetics and spectra (Klebesadel et al. 1973)
• Doppler boosting in relativistic jets moving towards theobserver
• Light jets with relativistic spine and slower sheath layer– Spine produces synchrotron optical and X-ray photons, that are
boosted to GeV and TeV gamma rays by inverse Compton inthe sheath (e.g. Chiaberge et a. 2000, Tavecchio & Ghisellini2008)
– Radio emission from extended (expanding) cocoon
Relativistic radio jets
FR II FR I
! > 4 ! " .210 kpc
! > 10 ! " 21 kpc
! " 5100 pc
! " 3-201 pc
! " 20-30 ! " 10-200.1 pc
(Giovannini et al. 2005, Laing et al. 2008)
Jet Dissipation
• Clusters and groups of galaxies emit X-rays
• Thermal bremsstrahlung from hot (0.5 keV up to 10
keV) gas confined in potential well: hot Intra-Cluster
Medium (ICM)
• Heating mechanism?
• Evidence that AGN jets affect the ICM
• X-ray cavities corresponding to radio lobes
• Shells surrounding the cavities
• Shell temperature lower than the surrounding
medium: weak shocks
X-rayX-ray
Fabian et al. (2003, 2005)
Perseus cluster (CHANDRA)
Work done to produce
cavities (Allen et al. 2006,
Heinz et al. 2007):
!
Lkin
=1037L" ,radio core
7 #1022$
% &
'
( )
12 /17
W
age
kint
WLVPW =!
"=
1#
#
!""#$%&'()'*(+$,-
!"#$$%&'(#)!*%+,%%)!+-%!'..$%(#)!#)+#!/0!')1!+-%!2%+!34)%(.!5#,%$!67&&%)
!%+!'&8!9::;<!0%4)=!%+!'&8!9::><!/'&?'@%$1%
!%+!'&8!9::AB
!
1) PB = M•
B c2 , M
•
B ="G2#B MBH
2
cs3
2)Pj = 8.6 $1022L% , radio core12 /17 erg s&1,'% = 0
C'14#!DE4%+
High resolution photometry and
spectroscopy from HST
Compact rotating SMBH
The disk-jet paradigm
RMHD Jet LaunchingF!G,#!%)%$HI!$%J%$@#4$JK
!!!L%5&%$4')!14J3!'..$%(#)!6#(.(#/$01$#2)'B
!!!L%$$!*&'.3!-#&%!$'541!$#+'(#)!6#3(.()"4563((((73(.()8954"(((((:;(<()(<(;B
•!G,4J+%1!?'H)%(.!M%&1!%N+$'.+J
!!!$#+'(#)'&!%)%$HI!'+!'!$'+%
!!!?'4)&I!4)!+-%!O#$?!#O!P#I)()H!QEN
•!R'JJ!#ES&#,!$'+%
•!G-%!J5%.4M.!%)%$HI
!!!4J!+-%!?'N4?E?!5#JJ4*&%
!!!T#$%)+=!O'.+#$!#O!+-%!#ES&#,
•!U-4.-!4J!+-%!'JI?5+#(.!T#$%)+=
!!!O'.+#$!!!!!!!!!!!')1!+-%!'..%&%$'(#)
!!!%V.4%).I!W
Acceleration efficiency
•!7)'&I(.!J#&E(#)J!6%8H8!$%@4%,!LX)4H&!9:Y:B
•!R4.-%&!6YZ;ZBK!'..%&%$'(#)!'&#)H!'!?#)#5#&'$!M%&1!%JJ%)('&&I
!!!%)1J!'+!+-%!O'J+[?'H)%+#J#)4.!JE$O'.%!,4+-
!!!!!!!!!!!!!!!4)%V.4%)+!'..%&%$'(#)
•!\)!'!)#)[$%&'(@4J(.!Q#,!!+-%!34)%(.!%)%$HI!'+!+-%!O'J+!JE$O'.%
!!!4J!'&$%'1I!Y]^!#O!+-%!+#+'&!%)%$HI!'@'4&'*&%
!!!!!!!!!!!!!!!'..%&%$'(#)!4J!?#$%!%V.4%)+!4)!+-%!.&'JJ4.'&!$%H4?%!_
•!/#+-!')'&I(.'&!J%&O[J4?4&'$!?#1%&J!6T4<!"-4E%-<!/%H%&?')!YZZ9<
!!!`&'-'34J!a!L#)4H&!9::^<!9::bB!')1!)E?%$4.'&!J4?E&'(#)J
!!!6L#?4JJ'$#@!%+!'&8!9::><!9::Z<!G.-%3-#@J3#I!%+!'&8!9::ZB
!!!JEHH%J+!+-'+!+-%!'..%&%$'(#)!5$#.%JJ!.')!*%!?E.-
!!!?#$%!%V.4%)+<!,4+-!!!!!!!!!!!!!!!!!!!!!!!!!#$!%@%)!-4H-%$
c5%.4M.!%)%$HIK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!d!34)%(.!e!P#I)()H
Numerical Simulations
•!c5%.4'&!$%&'(@4J(.!R0fK!H$'@4+'(#)'&!%g%.+J
!!!)%H&%.+%1<!O#.EJ!#)!&'$H%!J.'&%!'..%&%$'(#)
•!\)4('&!')1!*#E)1'$I!.#)14(#)JK
!!![!$#+'()H!*#E)1'$I
!!!!!hJ#&41!$#+'+#$!6/0]icB!e!L%5&%$4')!14J3j
!
Starting from “quasi-Keplerian” disk in equilibrium with gravity, thermal pressure gradient and
Lorentz force search for stationary states
Alpha prescription for momentum transport
Disk parameters: µ = B2/2P = 0.6
! = cs /VK = 0.1
H = ! r
"m = #m vA H exp[-2(z/H)2]
Cases: a) #m = 0.1 $m = 1 poloidal/toroidal
b) #m = 1 $m = 1
c) #m = 1 $m = 3
d) #m = 0.1 $m = 1 low resolution
2.5 D MHD
Codes
FLASH2.5
& PLUTO
with AMR
7 levels of
refinement
0 R equatorial plane 40
0 Z
Sym
metr
y a
xis
12
0
Open B
oundary
Open Boundary
Sink region
0 1
0 0
.5
Jet Acceleration
7&O@%)!JE$O'.%
T4H-+!JE$O'.%
kR!!JE$O'.%
T#$%)+=!l'??'
kR
P#I)()H
7&O@%) kR
7&#)H!'!?'H)%(.!JE$O'.%!,4+-!$:!d!Y
T#$%)+=!O#$.%
"%)+$4OEH'&
G#+'&
•!k&#,!!'..%&%$'+%J!%@%)
!!*%I#)1!kR!JE$O'.%!E5!+#
!!!!!!!!!!!!!!!,4+-!')!%V.4%).I
•!k&#,!4J!J(&&!'..%&%$'()H_
!!6)%%1!&'$H%$!J4?E&'(#)JB
•!k&#,!'..%&%$'+%1!*I
!!T#$%)+=!O#$.%J
!!6!!!!!!!5$%JJE$%B!!')1
!!.%)+$4OEH'&!%g%.+J
•!/%I#)1!kR!JE$O'.%
!!?'H)%(.!5$%JJE$%
!!1$4@%J!+-%!Q#,
!!6?'H)%(.!)#==&%<
!!T4!%+!'&8!YZZ9B
Jets, winds and (de)collimation
Initial
Final
Collimation
(Jet)
Decollimation
(Wind)
FMag FMag
• The magnetic force associated with the toroidal field (perpendicular to the
isosurfaces) tends to collimate the inner field lines and to decollimate the outer ones, creating a
configuration favorable for efficient acceleration.
• The structure suggests a fast jet (collimated) – slower wind (decollimated) configuration.
• In the relativistic regime, the electric force is comparable to the magnetic but with opposite sign:
differential collimation and acceleration are still possible but on very long spatial scales.
• Focus: magnetization
• Resistive 2.5D MHD simulations of
jet launching:
Tzeferacos et al. MNRAS 2009
! = 2P / B2
• Self-consistent jet ejection from
accretion disc
• Super Alfvènic, super fast
magneto-sonic outflows
• Steady state solutions obtained
only above equipartition plasma
! (case 1,2)
• From weak (case 1, 2) to strong
magnetic fields (case 3, 4)
1/3 ! " ! 10.0
• Strong correlation between
disk heating effects and
mass loading.
• Efficient acceleration and
stationarity is found for
mildly warm and cold
cases, comparable to slow
radio-galaxies and YSO jets
• Focus: entropy generation
due to viscous and Ohmic
heating
• Viscous and resistive 2.5D
MHD simulations of jet
launching
• # prescription for viscosity
and resistivity, with magnetic
Prandtl number:
Tzeferacos et al. (2011)
7&5-'!')1!14J3!')1!14J3!5-IJ4.'&5-IJ4.'&
5'$'?%+%$J5'$'?%+%$JWW
iE?%$4.'&!J4?E&'(#)J!#O!RC\
mg%.+J!#O!+-%!)E?%$4.JW
=>)11$'?2'?(=>)11$'?2'?(,>$,>$(())10>)(0#$-"#20%&'10>)(0#$-"#20%&'
2
2 !"
#$%
&'
= H
z
sHec()
R#?%)+E?!+$')J5#$+
`4J.#J4+I!#O!n[14J3JK
^f!-4H-[$%J#&E(#)!J4?E&'(#)
4)!J-%'$4)H!*#N!'55$#N4?'(#)
6c')#!a!\)E+JE3'!9::Y<!R4H)#)%!%+!'&!9::ZB
\)!'!.'$+%J4')!O$'?%!#O!$%O%$%).%!.#$#+'()H
,4+-!+-%!14J3
G-%!.-'))%&!J#&E(#)<!4)+%$?4o%)+!J+'+%J<
+$')J4(#)!+#!+E$*E&%).%<!.'&.E&'(#)!#O
R'N,%&&!J+$%JJ%J<!'J5%.+!$'(#!1%5%)1%).%
fI)'?#
R'N,%&&!J+$%JJ%J!')1!'&5-'
p)J+$'(M%1!J-%'$4)H!*#N%J!-'@%!*%%)
J-#,)!+#!JEg%$!O$#?!?')I!5$#*&%?J
6k$#?')H!%+!'&8!9::><!C%H%@!a!p?-E$')!9::A<!
/#1#!%+!'&8!9::A<!9:Y:B
\)!5'$(.E&'$!,4+-!=%$#!?%')
M%&1!+-%!+$')J5#$+!*%.#?%J!
)%H&4H4*&%!'+!-4H-!C%I)#&1J!
)E?*%$JK!'$(O'.+!#O!J-%'$4)H!*#N
G#,'$1J!H&#*'&!J4?E&'(#)J
Maxwell stressesa.r. 4
P$%&4?4)'$I!$%JE&+J!O$#?!J4?E&'(#)J!4)!,-4.-!H$'@4+'(#)'&!J+$'(M.'(#)!4J!4).&E1%1
c(&&!J-%'$4)H!*#N!.#)14(#)J!4)!+-%!$'14'&!14$%.(#)8!k4$J+!J+%5!+#,'$1J!H&#*'&!J4?E&'(#)J8
f#?'4)!J4=%!^0Nb0N;0!60!1%)J4+I!J.'&%!-%4H-+B8!9::!5#4)+J!5%$!J.'&%!-%4H-+8!
GE$*E&%)+!$%H4#)!4)!+-%!1%)J%$!$%H4#)!4)!+-%!?411&%
\)+%$%J()H!5#4)+K!5%$4#14.!O#$?'(#)!#O!-4H-&I!?'H)%(=%1!$%H4#)J!4)!+-%!E55%$!')1!&#,%$
$%H4#)J!6?'H)%(=%1!.#$#)'%B
7=4?E+-'&!
"#?5#)%)+
#O!+-%!?'H)%(.
!M%&18
!N[=!.E+
Relativistic Jet Propagation
• Are jets stable ?
• Do they dissipate magnetic flux ?
• Intrinsic/external instabilities
• How do jets decelerate without decollimating ?
• Mass entrainment from the ambient medium across
an unstable boundary layer! “internal” entrainment: diffusion of mass lost from stars
within the jet volume (Komissarov 1994)
! “external entrainment: ingestion of ambient gas from the
surrounding IGM via a turbulent unstable boundary layer
(Begelman 1982; De Young 1996)
• Connecting morphologies with dynamics
• Instabilities and turbulent particle acceleration
Interaction with external medium
• Shear instabilities in supersonic flows(Brown & Roshko 1974)
• Relativistic Kelvin-Helmholtz instabilities in
astrophysical jets (Ferrari et al. 1978, Hardee 1987, etc.)
• Stabilized by extended shear layers and longitudinal
magnetic fields; nonlinear saturation effects (Benford et
al. 1980)
! Solve the full set of inviscid relativistic hydro equations in 3D:
! Computational domain:
! Cartesian coordinates, homogeneous external medium, pressure
matched jet
! Perturbations at the jet inlet: pinching, helical, fluting%b = %b (1+!) & ! ' 0.05
! Relativistic Mach numberMr = %bvb/%svs
! Synge EoS
3D Relativistic Hydro Jets
outflow
outflow
outflowJet Inlet
+
perturbations yx
z
Mixing by Shear Instabilities
% = 10, M = 3, " = 102
% = 10, M = 3, " = 104
" Relativistic spine
surrounded by a turbulent
mixing layer
% = 10, M = 30, " = 102
A
B
E
Passive scalar
Comparison with observationsemissivity integration along the line of sight
at different projection angles
Agreement with Bridle & Laing empirical models
Intrinsic instabilities
• Current-driven kink instabilities related to a toroidalmagnetic field component in current carrying jets (Bateman1978, Appl et al. 2000, Giannios & Spruit 2006, Narayan et al. 2009)
• Stabilized by extended shears (Mizuno et al. 2007), jetexpansion (Moll et al. 2008, McKinney & Blandford 2009)
• Detailed nonlinear analysis required to test instabilityeffect on morphologies and radiation
Magnetized Jets
! M = Mach Number; " = (amb/(jet; % = Lorentz factor
! ) = Magnetization
!Poloidal model: uniform Bz
!Toroidal model:
! # = Rotation
!
B" =Bm
(r /a) for r < a
Bm
(a /r) for r > a
# $ %
!
"# =B#
2/$2
2 pg"z =
Bz
2
2 pg
!
v" (r) =#B" (r)
Bm
@A$",-(&B(C)?'$%"(D$1*-
! Toroidal models shows considerable deflection
! " intrinsic 3D effect
Axisym (“2.5” D) 3D LoRes 3D HiRes
RHD
(Hydro) RMHD
Poloidal RMHD
Toroidal
Pressure distribution
Magnetic Field Topology
Perturbation modes
! Hydro case and poloidal case:
prevailing of short KH wavelength
modes (Massaglia et al. ‘96,
Hardee ‘87)
! Toroidal case show suppression
of surface modes, kink modes
prevail
hydroPoloidal
Tor (HiRes)
Kinetic to Poynting flux ratio
• Initial radial equilibrium structure:
• Relativistic jets at the inlet % = 10
• Stratification " = (amb/(jet = 104 * 102
!
dp
dr"w# 2v$
2
r= % &E( )E + J 'B
Er = " v 'B( )r
= " vzB$ " v$Bz( )
J 'B( )r
= " Bz
dBz
dr+B$
r
d
drrB$( )
(
) *
+
, -
"dp
dr+w# 2v$
2
r=1
r2
d
dr
rB$( )2
2"rEr( )
2
2
(
)
* *
+
,
- -
+1
2
dBz
2
dr
" !"#$%
" !"#$&
J+$'(M.'(#)
'(
)
*+
,
iq!U4HH&4)H
/!,%'3
U4HH&4)H
/!J+$#)H
Fluxes A B C D* E F
Fk/FP 3.5 1 70 1000 3.5 1
Rotation 0 0 0 0 1 1
rP#)'&!M%&1
time
distance
ss s> ;: ;s
()-*",
t%+!.%)+%$[#O[?'JJ!5#J4(#)
• Large Poynting fluxes produce strong kinks, the head
of the flow becomes contorted
• Large kinetic fluxes avoid kinks, the heads of the jet
proceeds at large velocity
• The spine of the jet is always highly relativistic on the
average, shocks create intermittent structures
• When the jet encounters the low density region its
structure becomes again straight and kinks
disappear: hints of outflow acceleration ?
Experiment on supersonic (but not
relativistic) hydro jets (Torino, Milano)
Heavy Jet
Light jet
Conclusions• Relativistic jets show a nonlinear evolution that is different from non
relativistic jets in many aspects (AGN vs star)
• Acceleration of relativistic jets in the magneto-centrifugal scheme
extends beyond the fast-alfvenic point and is strictly correlated with the
collimation process
• Relativistic hydro jets are subject to strong mass entrainment by shear
instabilities and form naturally the spine/sheath layer structure
• Relativistic magnetized jets with strong toroidal component are subject
to kink instability that may disappear when they emerge from the
denser regions
• Entrainment and instabilities do not slow down the spine of the jet that
remains relativistic up to the hot spot/termination shock
• The issue of jet acceleration/deceleration requires further analysis of
dissipation and turbulent processes
• Particle acceleration: beyond MHD, PIC simulations
• Validation of codes on laboratory experiments is fundamental
