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Physics on the Extreme: Theoretical (high energy) A strophysics

Asaf Pe ’ er Room: 1.01c http://www.physics.ucc.ie/apeer. Physics on the Extreme: Theoretical (high energy) A strophysics. Asaf Pe ’ er. Physics on the Extreme: Theoretical (high energy) A strophysics. Astronomical Objects Physical Disciplines

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Physics on the Extreme: Theoretical (high energy) A strophysics

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  1. Asaf Pe’er Room: 1.01chttp://www.physics.ucc.ie/apeer Physics on the Extreme:Theoretical (high energy) Astrophysics

  2. Asaf Pe’er Physics on the Extreme:Theoretical (high energy) Astrophysics Astronomical Objects Physical Disciplines ★ Gamma-Ray Bursts (GRBs) ✪(relativistic) Dynamics ★ X-ray Binaries (XRBs) ✪ Radiative Processes ★ High Energy Cosmic Rays ✪Particle Acceleration ★ Tidal Disruption Events ✪Nuclear Interactions ★ Active Galactic Nuclei (AGNs) ✪Plasma (astro)physics

  3. Demonstration: Basic facts (1): GRB light curves- ZOO ! GRBs: flashes of gamma-rays that appear randomly in the sky. Duration:few s Variability:>~10 ms 60 s 150 s 5 s 5 s 40 s 0.5 s

  4. 100keV 100eV 1eV Basic facts (2): observed spectrum Observed Flux:~10-7 - 10-4 erg cm-2 s-1 Typical observed energy:<~ MeV Spectrum:non-thermal; extends to >GeV Isotropic in the sky  rays 10keV 100 MeV

  5. Theoretical implications Observed Flux: F ~10-7 - 10-4 erg cm-2 s-1 • Cosmological distancedL~ 1028 cm • Liso = F 4dL2 ~ 1050 - 1053 erg/s,released in few seconds (for comparison: Mc2~1054 erg: I.e., few % of solar rest mass released !) Variability:t~10 ms Light crossing time: R0 <~ ct ~ 3*108 cm Very compact object ! Number density of photons at MeV: Optical depth for pair productiongg e±: (me = 511 keV) We cannot see anything (>511 keV) !!

  6. Energy transfer: release –> kinetic -> dissipationeob = Ge’ Lorentz factor 100 Prediction: Afterglow ! Goodman, 1986; Paczynski, 1986; Rees & Meszaros, 1992,1994

  7. Relativistic jets:Very common in astronomy XRB’s 1E1740.7-2942 – 10’s AU (Mirabel & Rodriguez 1999) AGN’s M87 (>~1.5 kpc)

  8. 100keV 100eV 1eV Basic Question: Origin of the observed spectra ? Isotropic in the sky  rays 10keV 100 MeV

  9. Photons must originate Somehow. Synchrotron ?? • A very efficient way of producing non-thermal spectrum believed • Known to exist in many astronomical objects • Well understood Ingredients: Energetic electrons Magnetic field Known (at least ) from the 60’s(e.g., Ginzburg & Syrovatskii, 1965, 1969)

  10. So, basically the problem is reduced to: • Produce B field • Accelerate particles (elec.) to high energies Non is really known…. However, it is Believed, that shock waves can make all of this Introduce “ignorance parameters”: e, B

  11. State of the art Particle-in-cell simulation:study of formation of shock waves, generation of B-field & particle acc. Taken from Spitkovsky, 08

  12. In every shock crossing, particles gain energy Movie ! Taken from Spitkovsky, 08

  13. Asaf Pe’er Physics on the Extreme:Theoretical (high energy) Astrophysics Astronomical Objects Physical Disciplines ★ Gamma-Ray Bursts (GRBs) ✪(relativistic) Dynamics ★ X-ray Binaries (XRBs) ✪ Radiative Processes ★ High Energy Cosmic Rays ✪Particle Acceleration ★ Tidal Disruption Events ✪Nuclear Interactions ★ Active Galactic Nuclei (AGNs) ✪Plasma (astro)physics

  14. Few ideas for projects:(depends on student’s interest & background) • Dynamics of relativistic, magnetized shock waves • Properties of second (pair) photosphere • Signature of neutron (beta) decay; heavy elements • Monte-Carlo simulation of EM cascade following particle acceleration • Constraints on hadronic (proton) acceleration • Photospheric emission in magnetized outflow • Predictions for pre-cursor emission from late-time measurements • Constraints on jet geometry from lightcurve decay Asaf Pe’er; Room: 1.01c; http://www.physics.ucc.ie/apeer

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