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Extra Spectral Components due to Hadronic Cascade

Extra Spectral Components due to Hadronic Cascade. Katsuaki Asano (Tokyo Inst. Tech.). Collaboration with S.Inoue, P.Meszaros K.Murase, T.Terasawa. GRB 090510; Spectra. Band+ Extra PL. Extra Component in 090902B. Models.

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Extra Spectral Components due to Hadronic Cascade

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  1. Extra Spectral Componentsdue to Hadronic Cascade Katsuaki Asano (Tokyo Inst. Tech.) Collaboration with S.Inoue, P.Meszaros K.Murase, T.Terasawa

  2. GRB 090510; Spectra Band+ Extra PL

  3. Extra Component in 090902B

  4. Models • Early onset of afterglow (Ghirlanda+, Ghisellini+, Kumar & B.Duran etc.) • Inverse Compton with photosphere (Toma+) • Hadronic(Razzaque+, Ours) Zhang & Meszaros 2004, Piran 2005, Meszaros 2006, Dermer & Atoyan 2006. Gupta & Zhang 2007 etc. .. -> If true, it drastically changes our GRB picture.

  5. GRB: possible UHECR source Waxman 1995; Vietri 1995

  6. Proton acceleration efficiency We need 6-8 1043 ergs/Mpc3/yr to explain UHECRs See e.g. Murase+ 2008 We may need Up/Uγ>20. If GRB rate is 0.05 Gpc-3/yr, Up/Uγ>100 Note: Local CRs: p/e～100

  7. Much More Protons Primary Electron Components Asano+

  8. Cascade Processes ｐ＋γ→p+π0 ｐ＋γ→n+π＋ π0→γ+ γ π＋→μ＋+νμ ｐ＋γ→p + e- + e+ μ＋→e＋ + νμ+ νe γ＋γ→e- + e+ p, π±,μ±,e± →γ Synchrotron + Inv.Comp.: γ＋e → e Synchrotron Self-absorption: Iterative Method -> Both photon field and cascade processes are solved consistently.

  9. Proton Dominated? Proton E-2.0 E2n(E) Gamma Efficent for pion production PeV-EeV keV Energy To make gamma-rays from protons contribute enough, the proton energy largely exceeds the gamma-ray energy??

  10. Highest Energy The energy of particles is limited by two conditons. • The acceleration time ξRL/c < cooling time. • The acc. time ξRL/c < dynamical one Δ=R/Γ/c • Cooling Processes: • Proton Synchrotron+IC • Photoproduction of pions • Bethe-Heitler

  11. GRB 090510; Spectra Band+ Extra PL

  12. Asano, Guiriec & Meszaros 2009 Cascade due to photopion production Hard spectrum -> Low B -> Low pion production effic. gg-absorption R=1014 cm G=1500 Band component 3.4GeV Synchrotron and Inverse Compton due to secondary electron-positron pairs

  13. The cooling timescales (comoving frame) of protons due to synchrotron, inverse Compton, Bethe-Heitler, and photopion production are plotted. The dynamical timescale is R/Gc. A long cooling timescale -> low efficiency of pion-production The maximum energy is determined by the dynamical timescale.

  14. Proton Synchrotron R=1014 cm Even in this case, secondary pairs contribute

  15. Proton synchrotron case Synchrotron is the most efficient in this case. We suppress Emax to avoid too much secondary photons.

  16. Neutrinos from GRB 090510 “Bright” Neutrino We may need >10-2 erg/cm2 to detect with IceCube.

  17. GRB 090902B

  18. Naked Eye GRB GRB080319B Eiso～1054erg

  19. Constraint: Self-absorption Up seems too large.. One-zone approximation may be too simple.

  20. Summary • Low-energy excess is naturally explained by hadronic cascade. • Relatively high bulk energy is required in hadronic models. • But, it is consistent with the GRB-UHECR scenario. • GeV delay? Not self-apparent. • The pp contribution may not be so large.

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