COSMIC RAYS P PASQU ASQUALE ALE BL BLASI ASI INAF/ Arc rcet - - PowerPoint PPT Presentation

COSMIC RAYS

P PASQU ASQUALE ALE BL BLASI ASI

INAF/ Arc rcet etri Ast Astro rophysical O l Observato atory y

Knee 2nd knee? Dip/Ankle GZK?

THE ALL

• PARTICLE SPECTRUM

OUTLINE

• 1. The supernova paradigm for acceleration
• 2. The knee and the knees (chemistry)
• 3. The end of Galactic CRs
• 4. UHECRs
• a. Spectrum
• b. Anisotropy
• c. Chemical Composition

THE SUPERN THE SUPERNOVA P A PARADIGM ARADIGM

P PAR ARTICLE A TICLE ACCELERA CCELERATION TION

TEST P EST PART RTICLE T LE THEORY OF EORY OF DIFFU FUSIVE S E SHOCK AC K ACCELE LERATION ON

• 1. POWER LAW SPECTRUM WITH SLOPE
• 2. LOW ACCELERATION EFFICIENCY REQUIRED
• 3. MAXIMUM ENERGY

= R + 2 R 1 4

Emax~1-100 GeV<<Knee

BEYOND TEST PARTICLES: Non linear DSA

Berezhko & Voelk, PB, Amato & PB, Ellison et al…

NON LI NON LINEAR R THEORY EORY DYNAMICAL REACTION OF ACCELERATED PARTICLES CR INDUCED B-FIELD AMPLIFICATION DYNAMICAL REACTION OF AMPLIFIED B-FIELDS

Cosmic r Cosmic ray acceler y acceleration ation up t up to The knee

• The knee

DYNAMICAL REACTION

!"#$%"&'"( %)*+,-./01*(21*+.3(

&4567(8/5)-( v

,.0,4567(((((((!/16./,5/(

&%9&:'$;! "#$%&'()!*+%,'$#!

CR TRANSPORT EQUATION

• +

MASS, MOMENTUM, ENERGY CONSERVATION EQUATIONS

• 1. CONCAVE SPECTRA
• 2. HIGH ACCEL. EFFICIENCY
• 3. REDUCED HEATING
• 4. ESCAPE FLUX

!9<(=>0+6+(?(@>))5)+(ABBC(

SHOCK MODIFICATION

REDUCED REDUCED HEA HEATIN TING G

MAGNETIC FIELD AMPLIFICATION

SMALL PERTURBATIONS IN THE LOCAL B-FIELD CAN BE AMPLIFIED BY THE SUPER-ALFVENIC STREAMING OF THE ACCELERATED PARTICLES

METHOD: Write a Vlasov eq for each particle type Write Maxwell eqs for the fields Perturb them all Check if there are fourier modes that Develop a negative im(w) UNSTABLE MODES

GROWING MODES

Amato & PB 2009, Bell 2004

Amato & PB 2009

NON-RESONANT MODES grow faster only in the early phases of a SN

1000 years

SATURATION OF GROWTH

ALL RESULTS ARE OBTAINED IN PERTURBATIVE THEORY BUT THEY LEAD TO NON-PERTURBATIVE CONCLUSIONS (dB/B>>1). HARD TO PREDICT THE REAL SATURATION LEVEL (EVEN PIC SIMULATIONS DISAGREE ON CONCLUSIONS…)

BUT IT IS SUGGES BUT IT IS SUGGESTIVE THA TIVE THAT THE V T THE VAL ALUES INFERRED FR UES INFERRED FROM OM PER PERTURB TURBATIVE TIVE THEOR THEORY HINT T Y HINT TO O

B 100 µG

WHY IS IT INTERESTING:

• I. Reaching the knee?
• ./01.&!

DBE( DBF( DBC( DBG( !23!!!!!!!!!!!!!!!433 !!!!!!!!!!423!!!!!!!!!!!!!!533! !63! PR PROTON ON KNEE KNEE

PB, Amato & Caprioli, 2007 Amato & PB, 2006

9543(H+II(J+-45.-( 9K>3LM+I+6>-+5)(

WHY I HY IS I S IT I T INT NTEREST ESTING ( G (2)

WHY IS IT INTERESTING:

• II. Large B observed?

TYPICAL THICKNESS OF FILAMENTS: 10-2 -10-3 pc The synchrotron limited thickness is:

x = 4D(E) syn(E) 4 pc Bµ

• 3/2

B 100 µGauss

DYNAMICAL ROLE OF THE AMPLIFIED B-FIELD

• 1. LARGE B HIGHER MAX MOMENTUM PMAX
• 2. HIGHER PMAX LARGER SHOCK MODIFICATION
• 3. SHOCK MODIFICATION CONCAVE SPECTRA
• 4. LARGE B REDUCE MODIFICATION LESS

CONCAVE SPECTRA (Rtot~10) [Caprioli et al. 2008]

NARROW X-RAY RIMS MAGNETIC FIELD AMPLIFICATION MAGNETIC FIELD DAMPING

LARGE PMAX EFFICIENT ACCELERATION NO RIMS IN THE RADIO BAND SOME B AMPLIFICATION STILL NEEDED RIMS ALSO IN THE RADIO EMISSION NO ACCELERATION UP TO THE KNEE UNLESS… …ACCELERATION IN THE PERPENDICULAR REGIME CR INDUCED

(UPSTREAM)

PLASMA INDUCED

(DOWNSTREA M)

ONLY IF @ PERPENDIC. SHOCK

789:;<=>!!

?@*A;<=>!

6%+$'B%C!8./(%!D!*E!533F!

RXJ1713

THE MISSING LINK BETWEEN CRs AND ACCELERATED PARTICLES

WHAT IS THE SPECTRUM OF CR AT EARTH?

EXPANDING SHELL + ADIABATIC LOSSES DURING THE SEDOV-TAYLOR PHASE

N(E)E2 E

IN IN THE THE ABSENCE OF ABSENCE OF THIS ESC THIS ESCAPE PE FL FLUX UX ADIAB ADIABATIC L TIC LOSSES OSSES WOULD ULD MAKE REA MAKE REACHING CHING THE KNEE IMPOSSIBLE THE KNEE IMPOSSIBLE

$>L/+5M+<(!9(?(N3>-5(ABBO( P+/>7>,4Q+M+(?(!-.,7+)(ABBC(

ESCAPE FLUX WITH TIME

Q(E)dE Fesc(t) 1 2 Vs

3 4Rsh 2 dE max

dt dE E t1/2 dE E E -2 dE

E-2 WI

WITH NO CONNE TH NO CONNECTION CTION WI WITH TH THE INTRINSIC SPE THE INTRINSIC SPECTR CTRUM UM

$>L/+5M+<(!9(?(N3>-5(ABBO( P+/>7>,4Q+M+(?(!-.,7+)(ABBC(

PROTON SPECTRUM AT EARTH

EVIDENCE FOR A CUTOFF!

9/(/!,+%.!E#+(/'B/!#(!/$G!533H!

SPECTRA

PREDICTED SPECTRUM

ALL PARTICLE PROTONS ONLY Caprioli, PB & Amato 2009

SOME IMPLICATIONS

• 1. PROTONS ARE EXPECTED TO BE ACCELERATED T0 ~106 GeV
• 2. ACCELERATION IS Z DEPENDENT EMAX(Z)=Z EMAX
• 3. THE KNEE IS LIKELY TO BE THE RESULT OF OVERLAP

ON THE MAX ENERGY OF EACH SPECIE

• 4. GALACTIC CRs SHOULD END WITH IRON @ ~1017 eV

?

THE TRANSITION

• 1. The SNR paradigm hints to a

galactic cr spectrum ending at ~a few 1017 eV

• 2. Observations also suggest the

same trend

DIP MIXED ANKLE

PROPAGATION OF PROTONS

100 Mpc

GZK DIP P

MODIFICATION FACTOR

Aloisio, Berezinsky, PB & Ostapchenko 2008

HOW DOES THE SPECTRUM LOOK LIKE? THE DIP

Berezinsky et al. 2005 Aloisio et al. 2007

ACCIDENT OR PHYSICS?

Berezinsky et al. 2005 Aloisio et al. 2007

ENERGY SHIFTS WITHIN SYSTEMATICS FOR ALL EXPS BUT Auger

HISTORICAL INTERPRETATION OF THE TRANSITION: THE ANKLE

ALTERNATIVE INTERPRETATION OF THE TRANSITION: MIXED COMPOSITION

Allard et al. 2005-2008

UNDERSTANDING THE DIFFERENCE:

DIP VS MIXED

From Kampert 2008 From Sokolsky, SoCoR Workshop

UNDERSTANDING THE DIFFERENCE:

DIP VS ANKLE

Aloisio, Berezinsky, PB & Ostapchenko 2008

DIP ANKLE LE

XMAX and RMS OF XMAX

Auger HiRes

THE E GZK F FEATURE E

HiR iRes Auger r

From Roth (SoCOR Workshop)

CR Astronomy with PAO

SOME INCONSISTENCIES

• 1. PAO hints to a gradually heavier composition @ high E
• 2. …BUT THE GALACTIC B-FIELD LARGE DEFLECTIONS
• 3. WOULD THIS KEEP THE LARGE SCALE ANISOTROPY?
• 4. EVEN MOST MIXED COMPOSITION MODELS DO PREDICT
• 5. EVEN ASSUMING THAT WE ARE IN FACT SEEING HEAVY

NUCLEI (THEREFORE NO CORRELATION) THEN THE FLUX SUPPRESSION IS NOT THE GZK FEATURE

SOM SOME CON E CONCLUSION ONS

X-ray observations have probably provided us with the first evidence of b amplification This makes possible to reach the knee for protons Heavier nuclei follow with z The transition region would be naturally around 1017 eV The competing models of the transition can be Discriminated through composition studies UHECRs remain confusing…