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Astrophysical Evidence: UHECRs and GRBs Origin of Cosmic Rays: A Complete Model

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Astrophysical Evidence: UHECRs and GRBs Origin of Cosmic Rays: A Complete Model

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  1. Astrophysical Solution to the Problem of UHECR Origin: Gamma-Ray BurstsChuck Dermer(US Naval Research Laboratory)PANIC (Particles and Nuclei International Conference)Santa Fe, NM, 27 October 2005dermer@gamma.nrl.navy.milArmen Atoyan(UdeM)Jeremy Holmes(TJHSST, NRL, FIT)Stuart Wick(NRL, SMU) • Astrophysical Evidence: UHECRs and GRBs • Origin of Cosmic Rays: A Complete Model • High-Energy Neutrinos from GRBs: Test of GRB/Cosmic Ray model • Cosmic Rays from GRBs in the Galaxy

  2. Astrophysical Evidence for GRB Origin of Cosmic Rays 2nd knee knee ankle

  3. Ultra-High Energy Cosmic Rays (Greisen, Zatsepin, Kuzmin, or GZK effect) • AGASA observations show no cutoff (disagrees with HiRes observations) • New Auger results • Predicted cutoff above 1020 eV due to p + g  p0,p+interactions with Cosmic Microwave Background radiation Extragalactic Origin: (1) GZK cutoff (2) Pair production dip (3) Heavy-to-light transition at second knee

  4. High Energy Delayed Emission from GRB 940217 (Hurley et al. 1994) (Requires low-redshift GRB to avoid attenuation by diffuse IR background) Nonthermal Particle Acceleration in GRBs to multi-GeV energies Delayed second component in emission spectrum

  5. GRB 970417a TeV Detection with Milagrito (Atkins et al. 2002) (Requires low-redshift GRB to avoid attenuation by diffuse IR background) Other evidence for high-energy radiation from GRBs: Seven GRBs detected with EGRET either during prompt sub-MeV burst emission or after sub-MeV emission has decayed away (Dingus et al. 1998) Average spectrum of 4 GRBs detected over 200 s time interval from start of BATSE emission with photon index 1.95(0.25) (> 30 MeV)

  6. −18 s – 14 s 14 s – 47 s 47 s – 80 s 80 s – 113 s 113 s – 211 s GRB 941017 Light Curves Evidence for Cosmic Rays in GRB 941017 t90 = 77 s Anomalous g-ray component seen in 2 other GRBs t90 = 200 s González et al., Nature (2003)

  7. 2. Complete Solution to the Problem of CR Origin • Cosmic Rays below ≈ 1014 eV from SNe that collapse to neutron stars • Cosmic Rays above ≈ 1014 eV from SNe that collapse to black holes • CRs between knee and ankle/second knee from GRBs in Galaxy • CRs at higher energy from extragalactic/ cosmological origin Power-law transition at second knee Diversity of SN types (Wick et al. 2004)

  8. Energy-loss Mean Free Path of UHECR Protons on CMBR Photons • Energy Losses • Photopair • Photopion • Expansion z = 0

  9. Effects of Star Formation Rate on UHECR Spectrum USFR LSFR Assume luminosity density of GRBs follows SFR history of Universe Production of the ankle in extragalactic CR spectrum Ankle due to pair-production losses on CMBR (Berezinskii et al 2002)

  10. Best Fit to High Energy Cosmic Ray Data • Inject -2.2 spectrum (relativistic shock acceleration index) • Better fit with upper SFR • “Second knee” at transition between galactic and extragalactic components • Fits to KASCADE and HiRes data imply local luminosity density of GRBs • Requires large baryon load: fb ~ 50-200

  11. Fits to AGASA Data • Fit highest energy points with hard injection spectrum • Requires other sources for lower energy cosmic rays • GRB model implies AGASA results not valid • If correct, points to new physics • Will be resolved with Auger

  12. CR flux evolution from a local GRB: simple power-low D(E) (conserves the number of particles in rdif3) Injected CR energy: 1052 ergs at 1 kpc Emax=1021 erg,  = 2.2 D(1 PeV)= 1029 cm2 s-1,  =0.6 Galactic halo size: 10 kpc

  13. Diffusion of Cosmic Rays due to plasma turbulence Turbulence injection scales: ~1pc (SNR) & ~100pc (G. disc) Cosmic rays diffuse through stochastic gyro-resonant pitch-angle scattering with MHD wave turbulence. • Larmor • Radius: • Mean free path l for deflection by p/2: Wick, Dermer, & Atoyan (2004)

  14. CR flux evolution from a local GRB: model diffusion coefficient

  15. Fits to KASCADE data through the Knee GRB occurred ~2x105 years ago at a distance of ~500 pc (Wick et al, 2004) (similar for t ~1 Myr, at r ~ 1 kpc; depends on Dt)

  16. 3. Neutrinos from GRBs Standard Fireball/Blast Wave Model Leptonic emission processes: 1. Nonthermal synchrotron 2. Compton scattering Hadronic emission processes: 1. Photopion production 2. Cascade radiation

  17. Proton Injection and Cooling Spectra GRB synchrotron fluence Nonthermal Baryon Loading Factor fb = 30 Injected proton distribution Cooled proton distribution Forms neutral beam of neutrons, g rays, and neutrinos Escaping neutron distribution

  18. Neutrino Detection from GRBs only with Large Baryon-Loading Nonthermal Baryon Loading Factor fb = 20 (~2/yr)

  19. High Energy Emission from GRB Colliding Shells Very optically thick to gg attenuation in TeV range unless G >~ 1000 1 TeV Razzaque, Kobayashi, & Mészáros (2004)

  20. Neutral Beam Model for Anomalous g-rays in GRB 941017 G GRB jet CR protons n e- g Highly polarized nonthermal synchrotron radiation B Escaping neutron beam forming hyper-relativistic electrons/positrons Hadronic cascade radiation in jet Neutral Beam Model (Atoyan and Dermer, ApJ, 2003) for blazar jets Two hadronic emission components

  21. Photomeson Cascade Radiation Fluxes Photon index between −1.5 and −2 Fits data for GRB 941017 spectrum during prompt phase Photomeson Cascade: Nonthermal Baryon Loading Factor fb = 1 Ftot = 310-4 ergs cm-2 C3 S1 Total C2 S2 C4 S3 S4 C5 S5 MeV C1 d = 100 emits synchrotron (S1) and Compton (C1) photons emits synchrotron (S2) and Compton (C2) photons, etc.

  22. Photon and Neutrino Fluence during Prompt Phase Hard g-ray emission component from hadronic cascade radiation inside GRB blast wave with associated outflowing high-energy neutral beam of neutrons, g-rays, and neutrinos Nonthermal Baryon Loading Factor fb = 1 Ftot = 310-4 ergs cm-2 d = 100

  23. 5. Cosmic Rays from GRBs in the Galaxy  1 GRB every 10,000 – 100,000 years in the Milky Way (due to beaming) Fluence referred to Solar energy fluence in one second for significant effects on biology. Using constant-energy reservoir result implies where 105t5 yr is the mean time between galactic GRBs, and the GRB distance is

  24. Synchrotron and Compton Neutron-Decay Halos/ g-ray Pair Halos • Neutrons formed through photomeson processes during cosmic ray acceleration escape from blast wave n p + e- + ne • Decay of ultrahigh energy neutrons occurs at ~100 kpc • Produce nonthermal synchrotron radiation, depending on strength of halo magnetic field • Produce nonthermal g rays from Compton scattering of CMB • g rays materialize through gg e+e- • form extended pair and gamma-ray halo (Dermer 2002) (Aharonian, Coppi, and Völk 1994)

  25. Neutron Decay Emissions from a Galactic GRB Compton-scattered CMBR from Neutron-Decay Electrons formed by GRB associated with W49B (Ioka, Kobayashi, & Mészáros 2004)

  26. Biological Effects of Galactic GRBs GRB pointed towards Earth produced a lethal flux of high-energy photon and muons that destroyed the ozone layer, killed plankton, and led to trilobite extinction in the Ordovician Epoch (Melott et al. 2004) Geological evidence points toward two pulses; a prompt extinction and an extended ice age. Prompt neutrons and g-rays from a GRB could have produced the prompt extinction. Delayed cosmic rays could have produced the later ice age

  27. Summary • Complete model where Cosmic Rays originate from • SNe that collapse to neutron stars in the Galaxy (E<~1014 eV), • SNe that collapse to black holes (GRBs) in the Galaxy (1014 eV <~ E <~ 5x1017 eV), 3. Extragalactic SNe that collapse to black holes (GRBs) (E >~ 5x1017 eV) • GRB/Cosmic Ray model requires that GRBs are hadronically dominated • High-energy neutrino detection from GRBs only if GRBs are hadronically dominated • Anomalous hard g-ray emission component in GRB 941017 due to hadronic cascade radiation inside GRB blast wave (during prompt phase) and synchrotron radiation of hyper-relativistic electrons formed by outflowing neutrons (during prompt and extended phase) • Observation of GRB 941017 may provide first clear evidence for hadronic acceleration in GRBs and the sites where high-energy cosmic rays originate • GRBs in the Milky Way could have produced earlier extinction events • Effects of cosmic ray irradiation on Earth not yet fully explored

  28. Predictions • Heavy to light transition at the second knee • No multiplet events • Ankle is due to pair production dip • Display GZK cutoff, though must take into account enhanced GRB activity in local supercluster • Neutrinos from GRBs (IceCube) • Anomalous g-ray emission components in GRBs correlated with neutrino activity (GLAST) UHECRs from blazars? g-ray halos Pictor A Cygnus A

  29. GLAST Large Area Telescope (LAT) GLAST Burst Monitor (GBM)

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