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Physical conditions in potential UHECR accelerators

Physical conditions in potential UHECR accelerators. Sergey Gureev Astronomy Dept., Moscow State University Ksenia Ptitsyna Physics Dept., Moscow State University Sergey Troitsky Institute for Nuclear Research, Moscow. Constraints on astrophysical accelerators: “Hillas plot”

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Physical conditions in potential UHECR accelerators

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  1. Physical conditions in potential UHECR accelerators Sergey Gureev Astronomy Dept., Moscow State University Ksenia Ptitsyna Physics Dept., Moscow State University Sergey Troitsky Institute for Nuclear Research, Moscow

  2. Constraints on astrophysical accelerators: • “Hillas plot” • radiation losses • Particular sites: “Auger” AGN • manifold of active galaxies • an important detail of the Auger correlations • correlated objects important experimental updates for specific mechanisms from powerful BL Lacs to low-power Seyferts and LINERS how to calculate the chance probability? CAN THEY ACCELERATE PROTONS TO UHE?

  3. Constraints on astrophysical accelerators: • “Hillas plot” • radiation losses • Particular sites: “Auger” AGN • manifold of active galaxies • an important detail of the Auger correlations • correlated objects important experimental updates for specific mechanisms from powerful BL Lacs to low-power Seyferts and LINERS how to calculate the chance probability? CAN THEY ACCELERATE PROTONS TO UHE?

  4. Constraints on astrophysical accelerators: • “Hillas plot” + radiation losses (electrodynamics) • Assumption: • particle is accelerated by electromagnetic forces inside an astrophysical accelerator • General limitations: • geometry • radiation losses energetic particles leave the accelerator accelerating charges radiate and loose energy

  5. geometry:the Hillas criterion: Larmor radius < size of accelerator (otherwise lefts the accelerator) model-independent E<ZBR size of the accelerator maximal energy magnetic field charge Schluter & Biermann 1950 Hillas 1984

  6. the (original) Hillas plot Hillas 1984

  7. Boratav et al. 2000

  8. radiation losses: rate of E gain < rate ofE loss synchrotron curvature

  9. radiation losses: rate of E gain < rate ofE loss depend on the mechanism synchrotron curvature

  10. Limitations due to radiation losses: • disagreement on their importance? • protons can be accelerated “to (3-5)×1021 eV … • At energies ≥ 1022 eV the cosmic ray primaries have • to be heavy nuclei” Aharonyan et al. 2002 • “Practically, all known astronomical sources are • not able to produce cosmic rays with energies near few • times 1020 eV” Medvedev 2003

  11. Different acceleration regimes: • diffusive (shocks) • inductive (one-shot) • synchrotron-dominated losses • curvature-dominated losses

  12. Different acceleration regimes: • diffusive (shocks) plot: Medvedev 2003 gets a hit from time to time, radiates synchrotron continuously

  13. Different acceleration regimes: • diffusive (shocks) • gets a hit from time to time, radiates synchrotron continuously • inductive (one-shot) • synchrotron-dominated losses • curvature-dominated losses

  14. Different acceleration regimes: • inductive (one-shot) plot: Medvedev 2003 is accelerated and radiates continuously

  15. Different acceleration regimes: • diffusive (shocks) • gets a hit from time to time, radiates synchrotron continuously • inductive (one-shot) • is accelerated and radiates continuously • synchrotron-dominated losses • curvature-dominated losses general field configuration

  16. Different acceleration regimes: • diffusive (shocks) • gets a hit from time to time, radiates synchrotron continuously • inductive (one-shot) • is accelerated and radiates continuously • synchrotron-dominated losses • curvature-dominated losses general field configuration specific field configuration

  17. Different acceleration regimes: • diffusive (shocks) • gets a hit from time to time, radiates synchrotron continuously • inductive (one-shot) • is accelerated and radiates continuously • synchrotron-dominated losses • curvature-dominated losses general field configuration specific field configuration E ||B (close to a black hole)

  18. updated Hillas plots (plus radiation constraints) - diffusive acceleration

  19. updated Hillas plots (plus radiation constraints) - inductive acceleration, synchrotron losses

  20. updated Hillas plots (plus radiation constraints) - inductive acceleration, synchrotron losses

  21. updated Hillas plots (plus radiation constraints)

  22. Constraints on astrophysical accelerators: • “Hillas plot” • radiation losses • Particular sites: “Auger” AGN • manifold of active galaxies • an important detail of the Auger correlations • correlated objects important experimental updates for specific mechanisms from powerful BL Lacs to low-power Seyferts and LINERS how to calculate the chance probability? CAN THEY ACCELERATE PROTONS TO UHE?

  23. Auger correlations with AGN - the “AGN” term is misleading - 20% of galaxies show nuclear activity • luminosity, size, mass • scatter by orders of magnitude • powerful BL Lacs and radio galaxies • vs. low-power Seyferts and LINERs: • quite different positions on the Hillas plot!

  24. Auger correlations with AGN: various AGN on the Hillas plot

  25. Auger correlations with AGN: an important detail how to calculate the chance probability? list of events list of sources • calculate number of pairs “source-event” in data • compare with expected from Monte-Carlo • estimate the chance probability

  26. Auger correlations with AGN: an important detail how to calculate the chance probability? list of events list of sources number of pairs “source-event”: what if there are several sources for one event? 1. “Nearest neighbour”: one source for one event 2. “Correlation function”: count every pair

  27. Auger correlations with AGN: an important detail how to calculate the chance probability? 1. “Nearest neighbour”: one source for one event formal chance probability ~10-9 number of tries ~104 chance probability ~10-5 2. “Correlation function”: count every pair formal chance probability ~10-4 number of tries ~104 chance probability ~1

  28. Black hole neighbourhood: physics gouverned by the black hole mass • (safe) upper limit on B • size occupied by the field measure black hole mass estimate size constrain field estimate maximal energy

  29. measure black hole mass

  30. acceleration near black hole: no proton acceleration possible for iron, but huge deflection in GMF (no chance to correlate at 3 degrees)

  31. extended structures (jets, lobes)? • detected in 7 of 17 sources • extremely low power • no model-independent B measurements • equipartition: proper place on the Hillas plot • no proton acceleration • Cen A lobes may accelerate light nuclei

  32. Conclusions: • updated constraints on the UHECR accelerators • AGN=plausible accelerators • these are NOT low-power “Auger” AGN! • but powerful BL Lacs and radio galaxies • “Auger” AGN cannot accelerate protons • to observed energies • they can accelerate iron, but no correlations then! • Cen A = low-power radio galaxy, can accelerate medium-charge nuclei

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