1 / 28

PARTICLE ACCELERATION IN ASTROPHYSICAL SOURCES

PARTICLE ACCELERATION IN ASTROPHYSICAL SOURCES. Elena Amato INAF- Osservatorio Astrofisico di Arcetri. ACCELERATED PARTICLES IN THE COSMOS. EXTRA GALACTIC. GALACTIC. E -2.7/3. FINAL TEVATRON (2TeV). CERN LHC (14 TeV). Sub-GeV. ~EeV. ENERGETIC REQUIREMENTS. 1 eV/cm 3.

twyla
Download Presentation

PARTICLE ACCELERATION IN ASTROPHYSICAL SOURCES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PARTICLE ACCELERATION IN ASTROPHYSICAL SOURCES Elena Amato INAF-OsservatorioAstrofisico di Arcetri

  2. ACCELERATED PARTICLES IN THE COSMOS EXTRA GALACTIC GALACTIC E-2.7/3 FINAL TEVATRON (2TeV) CERN LHC (14 TeV) Sub-GeV ~EeV

  3. ENERGETIC REQUIREMENTS 1 eV/cm3 LARGE ENERGY DENSITY: EQUIPARTITION WITH B-FIELD AND THERMAL GAS LCR~3x1040 erg s-1 ~0.1 x 1051erg x 3x10-10s-1 ESN RSN E-2.7/3 FINAL TEVATRON (2TeV) CERN LHC (14 TeV) SUPERNOVA REMNANT PARADIGM (Baade & Zwicky 1934)

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

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

  6. EVIDENCE FOR RELATIVISTIC PROTONS 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….

  7. Cas A SUPERNOVA REMNANTS PARADIGM MUST BE PEVATRONS Tycho E-2.7/3 FINAL TEVATRON (2TeV) CERN LHC (14 TeV)

  8. STRONG SHOCKS: DOWNSTREAM UPSTREAM u1/u2=4  p=4  e=2 V ENERGY GAIN PER CYCLE FROM UPSTREAM FROM DOWNSTREAM V-v2 FERMI ACCELERATION MECHANISM PARTICLE GAINS ENERGY SOMETIMES LOSES ENERGY SOME OTHERS AVERAGE ENERGY GAIN PARTICLE GAINS ENERGY EACH TIME IT CROSSES THE SHOCK RETURN PROBABILITY INDEPENDENT OF E POWER LAW ENERGY SPECTRA ONLY DEPENDENT ON COMPRESSION RATIO V-v2

  9. COLLISIONLESS PLASMA… WAVE-PARTICLE INTERACTIONS!!! PARTICLE ISOTROPIZATION 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:Emax~GeV • IF B ~B0, Emax~103-104GeV (Lagage & Cesarsky 83) • AMPLIFIED B IS REQUIRED TO REACH THE KNEE

  10. BEFORE SCATTERING: PCR=nCRmCRvd AFTER SCATTERING: PCR=nCRmCRvA FOR RESONANT ALFVÉN WAVES MOMENTUM HAS GONE TO THE WAVES with SUPERALFVÉNIC STREAMING OF CRs  WAVE GROWTH PARTICLE DIFFUSION AND WAVE GROWTH IF CR ARE ISOTROPIZED BY THE WAVES… IN ADDITION 10% EFFICIENCY  SHOCK MODIFICATION!!!!

  11. SUBSHOCK CR PRECURSOR DENSITY OF ACCELERATED PARTICLES EFFICIENT ACCELERATION AT SNR SHOCKS • CR STREAMING INDUCES PRESSURE • GRADIENT UPSTREAM • A PRECURSOR IS FORMED: FLUID • PROGRESSIVELY SLOWS DOWN • CR ESCAPE MAKES SHOCK RADIATIVE • RTOT>4 WHILE RSUB<4 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)

  12. BASIC PREDICTIONS OF NL-DSA • 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 Blasi, Gabici, Vannoni 05 HINTS OF EFFICIENT ACCELERATION: • COMPRESSION RATIO > 4: • CD VS SHOCK IN TYCHO (Warren+ 05) • AND SN1006 (Cassam-Chenaii+ 08) AND • EMISSION PROFILES (Morlino+ 10) • T2 IS LOWER THAN EXPECTED: IN RCW86 • T2~1/10 TRH(Helder+ 09, Morlino+ 13) • CONCAVE SPECTRA: RADIO SNRs (Reynolds & Ellison 92) • AND SED FITTING OF SN1006 AND RCW86 (Vink 12) • B-FIELD LARGELY AMPLIFIED

  13. B~100-300G AMPLIFIED MAGNETIC FIELDS Tycho Cas A 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…

  14. CR AMPLIFIED FIELDS “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?

  15. B-FIELD EASILY AMPLIFIED TO FEW X 100 G (Riquelme & Spitkovsky 09, Caprioli & Spitkovsky 14) • BUT SCATTERING IN SMALL SCALE TURBULENCE -> D(p)p2 • 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 SATURATION & SCATTERING 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)

  16. Morlino & Caprioli 11 TYCHO STEEPENING THE SOURCE SPECTRA… • THEORY PREDICTS FLATTER THAN 2 • GAMMA RAYS SHOW STEEPER THAN 2 Caprioli 11 CAVEAT: DEPENDS ON DETAILS OF THE TURBULENCE PROPERTIES MIGHT EVEN FLATTEN THE SPECTRA FOR SLOW SHOCK PARTIAL IONIZATION STEEPENS SPECTRA (Morlino+ 13, 14)

  17. SEEING A PEVATRON 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

  18. A PEVATRON WE SEE… SYNCHROTRON AND ICS RADIATIONBY RELATIVISTIC PARTICLES ININTENSE (>few x 100 BISM) 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

  19. A PULSARS AND THEIR WINDS ROTATING CONDUCTING MAGNET SURFACE ELECTRIC FIELD EXTRACTS CHARGES PRIMARY CHARGES EMIT Υ-RAYS AND PAIR PRODUCE: LARGE MULTIPLICTY ~104-108 A DENSE RELATIVISTIC WIND MAINLY MADE OF PAIRS (THOUGH MAYBE PeV IONS…) AND A TOROIDAL B-FIELD LEAVES THE STAR: LORENTZ FACTOR ~ 104-FEW X 106 THE MOST RELATIVISTIC OUTFLOW IN NATURE AND THE MOST EFFICIENT ACCELERATOR KNOWN!!!

  20. Kes 75 (Chandra) (Gavriil et al., 2008) Gaensler & Slane 2006 PULSAR WIND NEBULAE • 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

  21. RELATIVISTIC SHOCKS IN ASTROPHYSICS AGNs~a few tens MQSs~a few SS433 Cyg A PWNe~104-106 GRBs~102 Crab Nebula

  22. THE PW TERMINATION SHOCK IS COLLISIONLESS • MECHANIMSMS FOR DISSIPATION AND ACCELERATION DEPEND ON FLOW • COMPOSITION(e--e+-p?) • MAGNETIZATION (=B2/4nmc2) • GEOMETRY( (B·n)) PARTICLE ACCELERATION • COMPOSITION: MOSTLY PAIRS BY NUMBER BUT…. • MAGNETIZATION:DYNAMICS -> >10-2FOR 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)

  23. FERMI PROCESS AT RELATIVISTIC PAIR SHOCKS 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 ELECTRON-ION SHOCKS….

  24. DRIVEN MAGNETIC RECONNECTION BROAD PARTICLE SPECTRA WITH =-(1-1.5) JUST RIGHT FOR PWN RADIO EMISSION BUT REQUIRED K>107 RECONNECTION BEFORE THE SHOCK? (Kirk & Skjaeraasen 03) (Sironi & Spitkovsky 11)

  25. RESONANT CYCLOTRON ABSORPTION IN ION DOPED PLASMA Configuration at the leading edge ~ cold ring in momentum space Magnetic reflection mediates the transition Coherent gyration leads to collective emission of cyclotron waves Drifting e+-e--p plasma B increases Pairs thermalize to kT~mec2 over 10-100 (1/ce) Ions take their time: mi/me times longer Plasma starts gyrating

  26. PARTICLE SPECTRA AND ACCELERATION EFFICIENCY • IONS CARRY MOST OF THE ENERGY: <mi/me • WIND SUFFICIENTLY COLD: u/u<me/mi IF ACCELERATION EFFICIENCY: ~few% for Ui/Utot~60% ~30% for Ui/Utot~80% SPECTRAL SLOPE: >3 for Ui/Utot~60% <2 for Ui/Utot~80% MAXIMUM ENERGY: ~20% mic2 for Ui/Utot~60% ~80% mic2 for Ui/Utot~80% RESULTS BY Amato & Arons 06 RECENTLY CONFIRMED BY Stockem et al 12 NEUTRINOS? (Amato et al 03)

  27. SUMMARY • 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

More Related