Cosmic Rays and Gamma Ray Bursts Origin of Cosmic Rays: A Complete Model - PowerPoint PPT Presentation

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Cosmic Rays and Gamma Ray Bursts Origin of Cosmic Rays: A Complete Model

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  1. Gamma Ray Bursts and the Origin of Cosmic RaysChuck Dermer(NRL)Colloquium, NRAO Charlottesville20 January 2005dermer@gamma.nrl.navy.milArmen Atoyan(UdeM)Jeremy Holmes(TJHSST, NRL, FIT)Stuart Wick(NRL, SMU) • Cosmic Rays and Gamma Ray Bursts • Origin of Cosmic Rays: A Complete Model • High-Energy Neutrinos from GRBs: Test of GRB/Cosmic Ray model • Evidence for Cosmic Ray Acceleration in GRBs: GRB 941017 • Cosmic Rays from GRBs in the Galaxy

  2. Discovery of Cosmic Rays • 1900: C. T. R. Wilson: atmospheric ionization (terrestrial?) • 1912: Victor Hess: altitude dependence of ionization (gamma rays?) • 1928: J. Clay: latitude dependence of ionization (electrons?) • 1934: Baade and Zwicky: SN explosions are sources of cosmic rays • 1938: T. H. Johnson: Ionization rate increased from E to W (positively charged sources of ionization – protons?) • 1949: Enrico Fermi: Cosmic rays accelerated by collisions with moving magnetic fields • 1977: Cosmic rays accelerated by supernova remnant shocks

  3. Discovery of Gamma-Ray Bursts • Discovery reported in 1973 from 1967-1973 Vela data • Cosmic g-ray flashes • Shock break-out from SNe (Colgate 1968) • Over 100 models at the time of BATSE/CGRO (1991) Klebesadel, Strong, & Olson (1973)

  4. 1. Cosmic Rays and Gamma Ray Bursts: Two Unsolved Problems in Astronomy Cosmic Rays Progress in the solution of one astronomical mystery – Gamma Ray Bursts – is leading to the solution of the mystery of Cosmic Ray Origin Supernova Origin Hypothesis Lack of Observational Confirmation/Origin of High-Energy Cosmic Rays Rare Type of Supernova Star-Forming Galaxies/ Highly Beamed/SN emissions Cosmological Origin GRBs

  5. Cosmic Rays The most energetic particles in the universe • Sources of • Light elements Li, Be, B • Galactic radio emission • Galactic gamma-ray emission • Galactic pressure • Galactic cloud heating • Terrestrial 14C • Genetic mutations

  6. 2nd knee knee ankle

  7. Ultra-High Energy Cosmic Rays (Greisen, Zatsepin, Kuzmin, or GZK effect) • AGASA observations show no cutoff (disagrees with HiRes observations) • Predicted cutoff above 1020 eV due to p + g  p0,p+interactions with Cosmic Microwave Background radiation What and where are the sources of Cosmic Rays? Multiple sources or single source type?

  8. Argument for the Supernova Origin of Cosmic Rays: Power • Local energy density of CR • uCR  1 eV cm-3  10-12 ergs cm-3 • Cosmic ray power requirements • LCR uCRVgal/tesc  51040 ergs s-1 • Galactic volume • Vgal  (15 kpc)2200 pc  41066 cm3 • Cosmic ray escape time from galaxy • tesc L/rc  10 gm-cm-2 / (mp 1 cm-3 c)  6106 yr • (information from 10Be used to determine mean density  smaller r and larger Vgal) • Galactic SN luminosity: 1 SN/ 30 yrs  ~1051 ergs in injection energy  • LSN  1042 ergs/s GeV/nucleon Ankle Knee Second Knee

  9. Argument for the Supernova Origin of Cosmic Rays: Acceleration Proton Larmor radius: rL 3 pc /BmG at E =3 1015eV (knee) • Particle acceleration at astrophysical shocks First order Fermi shock acceleration • Power-law particle energy spectrum with number index  2 (strong shocks) • Maximum particle energy • BISM 3 mGauss. What is R? • Particle acceleration suppressed when Emax near knee energy

  10. Prediction to Confirm Supernova Origin of Cosmic Rays • po gamma-ray bump near 70 MeV at SNRs, as seen in the diffuse galactic g-radiation (Ginzburg and Syravotskii 1964; Hayakawa 1969) Evidence for nonthermal electron acceleration in SN 1006 (Strong, Moskalenko, & Reimer 2000)

  11. However…Weak Observational Evidence for Hadronic CR Component in Galactic Supernova Remnants • Unidentified EGRET sources not firmly associated with SNRs and do not display strong p0 features; some appear to be associated with pulsars

  12. 100 MeV - TeV g Rays not detected at expected levels spp 30 mb Cas A Cassiopeia A; VLA Radio Image Upper limits on TeV fluxes from Whipple observations of SNRs (Buckley et al. 1997) Aharonian et al. (2001)

  13. TeV Emission Explained by Cosmic Ray Protons or Compton-Scattered CMBR? SNR RX J1713.7-3946: first mapped TeV source by HESS TeV Telescope in Namibia (Aharonian et al. 2004) Cas A Spectral Index = 2.190.09 characteristic of a shock spectrum Waiting for spatially resolved spectra ASCA 1-3 keV emission: contours

  14. Spectrum of Diffuse Galactic g–Ray Background Harderthan Expected from Locally Observed Cosmic Rays (Hunter et al. 1997)

  15. Origin, Composition, and Spectrum of Cosmic Rays above Knee of theCosmic Ray Spectrum unexplained • Nonrelativistic first-order shock-Fermi mechanism is incapable of accelerating particles to the ankle (~1019 eV) of the cosmic ray spectrum v0 = b0c is initial speed of supernova remnant shell; ~10,000 km/s • Obtain higher maximum particle energies for supernova remnants with faster initial speeds • What are speeds of supernova ejecta? Lagage and Cesarsky (1979)

  16. Different Types of Supernovae Type I: no H lines in spectra, Type II: H lines White Dwarf Detonation Supernova Ia: b0 = v0/c  0.02-0.1 Core Collapse Supernova Supernova II: b0  0.005-0.05 Supernova Ib: b0  0.03-0.1 (no H) Supernova Ic: b0  0.05-0.5 (no H, He) Collapse to neutron star GRBs: b0  1, G0  100-1000 Collapse to black hole? Burrows (2000)

  17. GRB 990123

  18. 0 2 4 6 8 Redshift Distribution • Redshift Distribution: • 0.1055 (GRB 031203) < z < 4.5 • Mean Redshift at z  1 • dL 2·1028 cm • Fluence and Energy: • Typical Fluences: 10-6 - 10-4 ergs cm-2 • Eg  1051 - 1054 ergs • X-Ray, optical and Radio Afterglows Gamma Ray Bursts: Basic Facts (Long Duration GRBs) Sample of Different GRB Light Curves Duration Distribution Kouveliotou et al. (1993)

  19. GRB-Supernova Connection GRB 980425/SN 1998bw (Type Ic SN) z = 0.0085 (~36 Mpc) Peak SN luminosity ~ 1.6x1043 ergs s-1 GRB 030329

  20. What are the Sources of Gamma Ray Bursts? (Long Duration) GRBs Linked to Massive Stars Gamma Ray Burst puzzle is far from solved SN 1998bw/GRB 980425 X-ray Lines and Features in 5-6 GRBs Supernova-Like Reddened Excesses in ~7 Optical Afterglows Standard Energy Reservoir Result ? GRB 030329 Supranova Model Two-step collapse to Black Hole Collapsar Model Direct collapse to Black Hole Environments of GRBs Chevalier & Li (1999, 2001, 2004) Panaitescu & Kumar (1999,2001)

  21. Meszaros and Rees, Paczynski, Piran… Observations: Large energy releases, large powers, short time variability, tgg Explanation: Deposit energy E in compact region to form pair fireball Result: Fireball adiabatically expands and reaches coasting velocity determined by baryon-loading Mb Coasting (initial) Lorentz factor:G0= E/Mbc2 Capture particle from surroundings: Directed kinetic energy  internal energy Bulk of swept-up energy in hadrons (if surrounding medium is not pair-dominated) Fireball/Blast Wave Model for GRBs Leptonic emission processes: 1. Nonthermal synchrotron 2. Compton scattering Blast wave formation and deceleration

  22. Blast Wave Model for GRBs Swift GLAST Radio Opt TeV 10 GeV MeV G0 = 600 Forward shock only

  23. 2. Complete Solution to the Problem of CR Origin (Wick et al. 2004) • 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 second knee from GRBs in Galaxy • CRs at higher energy from extragalactic/ cosmological origin

  24. Diffusion of Cosmic Rays due to Pitch Angle Scattering 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:

  25. Fits to KASCADE Data through the Knee of the Cosmic Ray Spectrum GRB occurred ~2x105 years ago at a distance of ~500 pc Likelihood of event Anisotropy

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

  27. Effects of Star Formation Rate on UHECR Spectrum Assume luminosity density of GRBs follows SFR history of universe

  28. 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

  29. 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

  30. 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

  31. Infrequently, a cosmic neutrino interacts with an ice or water nucleus • In the crash a muon (or electron, • or tau) is produced Cherenkov light cone muon interaction Detector (courtesy F. Halzen) • The muon radiates blue light in its wake • Optical sensors capture (and map) the light neutrino

  32. 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

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

  34. GRB 941017 Light Curves 4. Evidence for Cosmic Rays in GRBs: The Case of GRB 941017 González et al., Nature (2003) t90 = 77 s GRB 941017 Analyzed 26 BATSE/TASC GRBs GRB 941017: 11th highest fluence GRB in BATSE catalog Anomalous g-ray component now seen in 2 other GRBs t90 = 200 s

  35. −18 s – 14 s 1 MeV 100 MeV 14 s – 47 s 47 s – 80 s 80 s – 113 s Hard (-1 photon spectral index) spectrum during delayed phase 113 s – 211 s Fluence, including hard g-ray component, is > 6.5 10-4 ergs cm-2 Typical hard-to-soft evolution of GRBs Hard component observed both with BATSE and TASC

  36. 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

  37. 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.

  38. 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

  39. Radiation Physics of Neutron/Hyper-relativistic Electron Beam g 2g e± g n p0 2qj Synchrotron energy-loss rate: Synchrotron energy-loss timescale: Gyration frequency: WhenwBtsyn << 1, hyper-relativistic electrons When wBtsyn << qj, electrons emit most of their energy within qj n p± m± e± g GRB source GRB jet B g

  40. Hyper-relativistic Electron Synchrotron Radiation Mean energy of synchrotron photons emitted by electrons with g = ghrj: e± with g > ghrj 2qj g e± with g > ghrj GRB source GRB jet g B , i.e., a −1 photon spectrum • ≈ 200 sec decay timescale • external radiation field ( R ≈ 61014 cm, qj ≈ 0.14 for z=1) • Fluence ratio  hadronically dominated, and large nm flux Issues:

  41. 5. Cosmic Rays from GRBs in the Galaxy Numerical simulation model of cosmic ray propagation from jetted GRBs in the Milky Way Larmor radius of a particle spiraling in a magnetic field

  42. Magnetic Field Model of the Galaxy Cosmic rays move in response to a large-scale magnetic field that traces the spiral arm structure of the Galaxy, and to pitch-angle scattering with magnetic turbulence in the Galactic magnetic field. Disk magnetic field: Alvarez-Muniz, et al. (2000) The typical Galactic magnetic field near Earth is 3-4 mGauss Combined finite difference/Monte Carlo simulation for motion of cosmic ray protons and ions, and protons formed from neutron decay.

  43. Cosmic Ray Neutrons Neutrons are also formed in high-energy cosmic ray sources Neutrons decay on time scales of 920g seconds, due to time dilation (about 1 kpc for g=108), and then gyrate in magnetic field Cosmic ray neutrons decay over a pathlength

  44. Trajectories of Cosmic Rays in the Galaxy

  45. Cosmic Rays from GRBs GRB located at 3 kpc from center of the Galaxy GRB emission is jetted with jet opening angle of 0.1 radian Jet is pointed radially outward along Galactic plane

  46. Rate of GRBs into Milky-Way--Type (L*) Galaxies • BATSE obs. imply ~ 2 GRBs/day over the full sky • Beaming factor increases that rate by factor ~500 • Volume of the universe ~ 4p(4000 Mpc)3 /3 • Density of L* galaxies ~ 1/(200-500 Mpc3) Rate per L* galaxy KFT correction factor for clean and dirty fireballs  1 GRB in the Milky Way every 10,000 – 100,000 years

  47. Rate of Irradiation Events by GRBs 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

  48. Effects of Cosmic Rays from Galactic GRBs Extinction episodes (Dar, Laor & Shaviv 1998) Melott et al. (2004) suggest that a GRB pointed towards Earth produced a lethal flux of high-energy photon and muon radiation flux that destroyed the ozone layer, killed plankton, and led to trilobite extinction in the Ordovician Epoch However, geological evidence points toward two pulses; a prompt extinction and an extended ice age. The prompt neutrons and gamma-rays from a GRB could have produced the prompt extinction. The delayed cosmic rays could have produced the later ice age

  49. Flux of Cosmic Rays from GRB Jet Pointed towards the Earth Fluxes of cosmic ray neutrons, neutron-decay protons, and protons passing near Earth as a function of time for cosmic ray Lorentz factors between 108 and 109. The source of high-energy cosmic rays is located 1000 parsecs from the Earth, with the GRB jet pointed in our direction. As many as three phases of cosmic ray irradiation are found: • Prompt neutron (and gamma-ray) flux, • Neutron-decay protons, • Cosmic ray protons produced at the GRB source.