EXTRA
GALACTIC
GALACTIC
E -2.7/3
Sub-GeV ~EeV

1 eV/cm 3
LARGE ENERGY DENSITY:
EQUIPARTITION
WITH
B-FIELD AND THERMAL GAS
L
CR
~3x10 40 erg s -1
~ 0.1
x 10 51 erg x 3x10 -10 s -1
E
SN
R
SN
SUPERNOVA REMNANT
PARADIGM
(Baade & Zwicky 1934)
E -2.7/3

Cas A
Tycho
RX J1713.7
RELATIVISTIC ELECTRONS
SEEN THROUGH
X-RAY EMISSION SN 1006

TeV EMISSION DETECTED!
RX J1713.7
NEUTRAL PION-DECAY
OR
INVERSE COMPTON SCATTERING
OF ELECTRONS?
DETAILED SPECTRAL
MODELING REQUIRED!
CONCLUSION
UNCERTAIN
IN MOST CASES
BUT….
SN 1006

W44
Cardillo+ 14
“PION BUMP” IN MIDDLE AGED SNRs INTERACTING WITH
MOLECULAR CLOUDS Fermi (Abdo+ 09,10; Ackerman+ 13) & Agile (Giuliani+ 10,11;
Cardillo+ 14)
IC443
NOT
VERY
ENERGETIC
PROTONS
THOUGH….

Cas A
Tycho
MUST BE PEVATRONS
E -2.7/3

PARTICLE GAINS ENERGY
SOMETIMES
LOSES ENERGY SOME OTHERS
AVERAGE ENERGY GAIN
DOWNSTREAM UPSTREAM
V
FROM UPSTREAM
PARTICLE GAINS ENERGY
EACH TIME IT CROSSES THE
SHOCK
ENERGY GAIN PER
CYCLE
RETURN PROBABILITY INDEPENDENT OF E
POWER LAW ENERGY SPECTRA ONLY
DEPENDENT ON COMPRESSION RATIO
N ( p ) p p g p
= u
1
3 u
1
u
2
FROM DOWNSTREAM
V-v
2
V-v
2
STRONG SHOCKS: u
1
/u
2
=4   p
=4   e
=2

COLLISIONLESS PLASMA…
WAVE-PARTICLE INTERACTIONS!!!
PITCH ANGLE DIFFUSION:
->SPATIAL DIFFUSION
INTERACTIONS MOST EFFICIENT AT RESONANCE
ACCELERATION TIME DEPENDS ON
TURBULENCE LEVEL
MAXIMUM ACHIEVABLE ENERGY DEPENDS ON
TURBULENCE LEVEL
 IF

B SAME RESPONSIBLE FOR CR CONFINEMENT IN THE GALAXY:
E max
~GeV
 IF  B ~B
0
, E max
~10 3 -10 4 GeV (Lagage & Cesarsky 83)
• AMPLIFIED B IS REQUIRED TO REACH THE KNEE

IF CR ARE ISOTROPIZED BY THE WAVES…
BEFORE SCATTERING
: P
CR
=n
CR m 
CR v d
AFTER SCATTERING
: P
CR
=n
CR m 
CR v
A
FOR RESONANT
ALFVÉN WAVES dP
CR dt
= dP w dt
=
1 v
A dE w dt
=
1 v
A
2 g w d ( )
8 p
2 dP
CR dt
=
* n
CR m g
CR t
( v d
v
A
)
MOMENTUM HAS
GONE TO THE WAVES n
*
CR
= n
CR
æ p
> eB with ck
SUPERALFVÉNIC STREAMING OF CRs  WAVE GROWTH
ø
IN ADDITION 10% EFFICIENCY

SHOCK MODIFICATION!!!!

 CR STREAMING INDUCES PRESSURE
SUBSHOCK
GRADIENT UPSTREAM
 A PRECURSOR IS FORMED: FLUID
PROGRESSIVELY SLOWS DOWN
 CR ESCAPE MAKES SHOCK RADIATIVE
R
TOT
>4 WHILE R
SUB
<4
CR PRECURSOR
DENSITY OF ACCELERATED PARTICLES
DIFFERENT ENERGY PARTICLES HAVE DIFFERENT DIFFUSION LENGTHS
 EXPERIENCE DIFFERENT R (<4 AT LOW EN, >4 AT HIGH EN)
 SPECTRUM BECOMES CONCAVE (STEEP AT LOW EN. FLAT AT HIGH)

 BACK-REACTION OF CRs
 MAGNETIC FIELD AMPLIFICATION
 BACK-REACTION OF AMPLIFIED
FIELD
TWO-FLUIDS
:
Drury & co.
MONTECARLO
:
Ellison & co.
FINITE DIFFERENCE
:
Berezhko, Volk & co .
KINETIC: Amato & Blasi 05,06; Blasi+ 08
Caprioli+ 08,09,10,11
HINTS OF EFFICIENT

ACCELERATION:
CD VS SHOCK IN TYCHO (Warren+ 05)
Blasi, Gabici, Vannoni 05
AND SN1006 (Cassam-Chenaii+ 08) AND
EMISSION PROFILES ( Morlino+ 10)
 T
2
IS LOWER THAN EXPECTED
T
2
~
1/10 T
RH
:
(Helder+ 09, Morlino+ 13)
IN RCW86
 CONCAVE SPECTRA : RADIO SNRs ( Reynolds & Ellison 92)
AND SED FITTING OF SN1006 AND RCW86 (Vink 12)
 B-FIELD LARGELY AMPLIFIED

Cas A
Tycho
B~100-300  G
IN THE
SIMPLEST PICTURE
EFFICIENT PARTICLE ACCELERATION
BECAUSE OF HIGH B-FIELD
HIGH B-FIELD BECAUSE OF
EFFICIENT PARTICLE ACCELERATION
CAVEAT:
LARGE MAGNETIC FIELDS MIGHT HAVE DIFFERENT ORIGIN
AND DO NOT IMPLY EFFICIENT SCATTERING…

“STANDARD” GROWTH RATE
ONLY APPLIES WHEN
OTHERWISE GROWTH OF RESONANT MODES IS SUPPRESSED
NON RESONANT MODES (Bell 04, Amato & Blasi 09) BECOME DOMINANT
 CR CURRENT INDUCES
COMPENSATING CURRENT IN
PLASMA

INDUCES TRANSVERSE
PLASMA MOTION
 RESULTING CURRENT ACTS AS A
SOURCE OF B
 FOR RIGHT-HAND POLARIZED
WAVES, FIELD LINES ARE
STRETCHED:
FIELD IS AMPLIFIED
VERY LARGE FIELD ON
VERY SMALL SCALES
EFFICIENT FOR SCATTERING?

• B-FIELD EASILY AMPLIFIED TO FEW X 100 
G (Riquelme & Spitkovsky 09,
Caprioli & Spitkovsky 14)
• BUT SCATTERING IN SMALL SCALE TURBULENCE -> D(p)  p 2
 ONLY EXTREME SNRS REACH THE KNEE (Zirakashvili & Ptuskin 08)
• BUT BELL’S TURBULENCE MIGHT SEED A DYNAMO
(Bykov+13)
• NUMERICAL WORK
(Caprioli & Spitkovsky 14): SCALE INDEED GROWS
QUICKLY AND SCATTERING IS IN BOHM REGIME
SELF-REGULATING ACCELERATION AND ESCAPE
LITTLE TURBULENCE LARGE ESCAPE
FRACTION
LARGE CURRENT
CURRENT DECREASES
EFFICIENT
ACCELERATION
TURBULENCE
INCREASES
EFFICIENT FIELD AMPLIFICATION ALSO HELPS RECONCILING OBSERVED
SPECTRA WITH OBSERVATIONS (Zirakashvili & Ptuskin 08, Caprioli 11)

• THEORY PREDICTS FLATTER THAN 2
• GAMMA RAYS SHOW STEEPER THAN 2 r
¢ = u
1 a = u
2
+ ¢
,1
+ ¢
,2
Caprioli 11
Morlino & Caprioli 11 r
¢ +
2 r
¢ -
1
>
2
TYCHO
CAVEAT : DEPENDS ON DETAILS OF
THE TURBULENCE PROPERTIES
MIGHT EVEN
FLATTEN THE SPECTRA
FOR SLOW SHOCK PARTIAL IONIZATION
STEEPENS SPECTRA (Morlino+ 13, 14)

Schure & Bell 13
PEVATRONS: EXTREME TYPE II FOR FEW X10 YR HARD TO SEE
Gallant, Amato, Lavalle in prep.
HOWEVER ONE COULD
SEE ESCAPED PeV
PARTICLES
FOR MUCH LONGER
(Gabici & Aharonian 07)
WITH UPCOMING
TELESCOPES
POSSIBLE TO CHECK ON CAS A

SYNCHROTRON AND ICS RADIATION BY
RELATIVISTIC PARTICLES
IN INTENSE
(>few x 100 B
ISM
)
ORDERED
(HIGH POLARIZATION, IN RADIO, OPTICAL
AND EVEN
 -
RAYS
,
Dean et al 08
)
MAGNETIC FIELD
PeV ELECTRONS
SOURCE OF B FIELD
AND PARTICLES:
NS SUGGESTED
BEFORE
PSR DISCOVERY
( Pacini 67 )
Atoyan & Aharonian 96

ROTATING CONDUCTING MAGNET SURFACE ELECTRIC FIELD
EXTRACTS CHARGES
PRIMARY CHARGES EMIT
Υ-RAYS AND PAIR PRODUCE:
LARGE MULTIPLICTY
~
10 4 -10 8
A DENSE RELATIVISTIC WIND
MAINLY MADE OF PAIRS
( THOUGH MAYBE PeV IONS… )
AND A TOROIDAL B-FIELD
LEAVES THE STAR:
LORENTZ FACTOR
~
10 4 -FEW X 10 6
THE MOST RELATIVISTIC
OUTFLOW IN NATURE
AND THE MOST EFFICIENT
ACCELERATOR KNOWN!!!

• WIND IS CONFINED BY
SURROUNDING SNR (OR ISM IN
OLDER SYSTEM)
• WIND MUST SLOW DOWN TO
MATCH SNR EXPANSION SPEED
• THIS HAPPENS THROUGH A SHOCK
TRANSITION
Gaensler & Slane 2006
Kes 75 ( Chandra )
(Gavriil et al., 2008)

MQSs

~a few
AGNs

~a few tens
SS433
PWNe

~10 4 -10 6
Cyg A
GRBs

~10 2
Crab Nebula

THE PW TERMINATION SHOCK IS COLLISIONLESS
MECHANIMSMS FOR DISSIPATION AND ACCELERATION DEPEND ON
FLOW
• COMPOSITION
(e -e + -p?)
• MAGNETIZATION
(  =B 2 /4  n  mc 2 )
• GEOMETRY
(   ( B·n ))
• COMPOSITION: MOSTLY PAIRS BY NUMBER
BUT….
• MAGNETIZATION :DYNAMICS ->  >10 -2
FOR MOST OF THE FLOW
• GEOMETRY : TRANSVERSE
PROPOSED MECHANISMS:
 FERMI MECHANISM IF/WHERE MAGNETIZATION IS LOW ENOUGH
 DRIVEN MAGNETIC RECONNECTION AT THE SHOCK
(Lyubarsky 03, Lyubarsky & Liverts 08, Sironi & Spitkovsky 11 )
 RESONANT CYCLOTRON ABSORPTION IN ION DOPED PLASMA
( Hoshino et Al 92, Amato & Arons 06 )

RESULTS FROM PIC
SIMULATIONS BY
Spitkovsky 08,
Sironi & Spitkovsky 09, 11
EFFICIENT ACCELERATION AT UNMAGNETIZED SHOCKS
NO ACCELERATION AT SUPERLUMINAL SHOCKS
NOT EVEN FERMI PROCESS AT LARGE OBLIQUITIES…
SAME CONCLUSIONS FOR ELECTRONION SHOCKS….

BROAD PARTICLE
SPECTRA WITH

=-(1-1.5)
JUST RIGHT FOR
PWN RADIO EMISSION
BUT
REQUIRED K>10 7
RECONNECTION
BEFORE THE SHOCK?
(Kirk & Skjaeraasen 03)
( Sironi & Spitkovsky 11)

Configuration at the leading edge
~ cold ring in momentum space
Magnetic reflection mediates the transition
Drifting e + -e -p plasma
B increases
Plasma starts gyrating
Coherent gyration leads to collective emission of cyclotron waves
Pairs thermalize to kT~m e
 c 2 over
10-100  (1/  ce
)
Ions take their time: m i
/m e times longer

IF
• IONS CARRY MOST OF THE ENERGY:

<m i
/m e
• WIND SUFFICIENTLY COLD:
 u/u<m e
/m i
ACCELERATION EFFICIENCY :
~few% for U
~30% for U i i
/U tot
~60%
/U tot
~80%
SPECTRAL SLOPE :
>3 for U
<2 for U i i
/U tot
~60%
/U tot
~80%
MAXIMUM ENERGY :
~20% m
~80% m i i c 2  for U c 2  for U i i
/U
/U tot tot
~60%
~80%
(Amato et al 03)

• PARTICLE ACCELERATION AT SNR SHOCKS IS A SELF-
REGULATING PROCESS WELL DESCRIBED BY NLDSA
THEORY
• ACCELERATION UP TO THE “KNEE” LIKELY POSSIBLE
FOR A SHORT TIME AFTER THE SN EXPLOSION
• NO EVIDENCE YET FOR PEVATRONS AMONG SNRs BUT
HOPES FOR THE NEAR FUTURE
• PeV ELECTRONS ARE SEEN IN PWNe:
THE CRAB NEBULA IS
THE MOST EFFICIENT ACCELERATOR DIRECTLY OBSERVED IN
NATURE!
• THE MAIN ACCELERATION PROCESS IS NOT FULLY
UNDERSTOOD
• THE PRESENCE OF PEV IONS COULD PROVIDE A
POSSIBLE SOLUTION TO THIS PUZZLE