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Gamma rays from UHECRs in the Jets of FSRQs

High Energy Astrophysics Division Meeting Newport, RI September 7, 2011. Gamma rays from UHECRs in the Jets of FSRQs. Charles Dermer United States Naval Research Laboratory Washington, DC USA charles.dermer@nrl.navy.mil Kohta Murase (OSU), Hajime Takami (MPI).

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Gamma rays from UHECRs in the Jets of FSRQs

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  1. High Energy Astrophysics Division Meeting Newport, RI September 7, 2011 Gamma rays from UHECRs in the Jets of FSRQs Charles Dermer United States Naval Research Laboratory Washington, DC USA charles.dermer@nrl.navy.mil Kohta Murase (OSU), Hajime Takami (MPI) Location of g-ray emission region in blazars---origin of UHECRs • Outline • Observations of PKS 1222+2163 • Pair production opacity in the BLR and Dust Torus • Model for High Energy Radiation • Ultra-high energy cosmic rays and TeV blazar emission Dermer HEAD, Newport, RI 2011 September 7

  2. Observations of PKS 1222+2163 MAGIC spectrum PKS 1222+2163 = 4C +21.35, z = 0.432 MAGIC observations • Emission over 30 minutes • Flaring on timescales of 10 minutes • nFn peak at 1 – 10 GeV • Fermi LAT observations • at GeV energies: day scale variability Lg ~ 1048 erg/s MAGIC light curve Fermi-LAT and MAGIC spectrum Aleksic et al. (2011) Tanaka et al. (2011) Dermer HEAD, Newport, RI 2011 September 7

  3. IR Emission from 4C +21.35 Epoch 2 (August 2008) Epoch 1 (June 2007) Malmrose et al. (2011) • Model Spitzer (5 – 35μ), SDSS, 2MASS, and Swift UVOT data of 4C +21.35 • Decompose spectrum into nonthermal power-law and • two-temperature dust model. • Hot dust with T ≈ 1200 • K radiates ≈ 8 × 1045 erg s−1 from ~pc scale • Second warm dust component radiates ≈ 1045 erg s−1 at T ≈ 660 K, also on pc scale • BLR radiation Dermer HEAD, Newport, RI 2011 September 7

  4. Pair Production and Photohadronic Opacity Dermer HEAD, Newport, RI 2011 September 7

  5. Neutron-Beam Model for High Energy Radiation g B n,e+ e+ p0, p n,p 2g g n,e- e- ~1017 cm ~ pc Activity in inner jet accelerates UHECR protons with energies ~1019 – 1020 eV Interactions with internal and external radiation fields result in UHECR neutrons due to photohadronic processes (Atoyan & Dermer 2003) Highly collimated neutron beam formed through external scattering processes Neutrons escape inner jet and undergo n + g  n + po, p + p+with IR photons Secondary electrons and positrons make GeV  TeV synchrotron radiation Dermer HEAD, Newport, RI 2011 September 7

  6. Maximum Particle Energy Maximum particle energy from (1) Hillas condition, (2) Luminosity constraint on Fermi acceleration, Minimum Lorentz factor from γγ opacity leaving allowed particle energies limited to values indicated by shaded area. Dermer HEAD, Newport, RI 2011 September 7

  7. Variability from Synchrotron Radiation Synchrotron energy-loss MFPs of electron with Lorentz factor γe in a tangled magnetic field ranging from 1 μG to 10 mG. Compton energy-loss MFPs are plotted for CMB radiation, and graybody IR radiation fields from hot (T = 1200 K) and warm (T = 660 K) dust, assuming distance R = 1 pc. Vertical lines represent the range of γe from the decay of π+ from photopion interactions of UHECR neutrons. The cross-hatched region represents range of γeand magnetic fields where 10 minute variability can be preserved T Dermer HEAD, Newport, RI 2011 September 7

  8. Cascade Radiation Spectrum Injection throughout the pc scale Includes Compton-scattered dust radiation Synchrotron emission due to ultra-relativistic leptons (can be in jitter regime) Obtain few percent efficiency for g-ray production; therefore require ~1049 erg/s apparent isotropic luminosity in UHECRs

  9. Conclusions • 70 GeV – 400 GeV radiation from PKS 1222 highly attenuated if made in the sub-pc scale • Rapid VHE variability is inconsistent with formation at the pc scale • Propose model where activity in the central engine accelerates UHECR protons, making an escaping neutron beam • Photohadronic production of neutrons on IR emission makes highly relativistic electrons and positrons, and synchrotron emission of these secondaries makes highly variable VHE radiation • UHECR production complicates (solves?) question of location of emission region • Hadronic cascade scenario can be distinguished from leptonic scenarios by observing gamma-ray above 25 TeV in 1ES 0229+200 Dermer HEAD, Newport, RI 2011 September 7

  10. Cascading g rays from blazars: a test for UHECR origin • rays from photopair production by UHECR protons Essey et al. 2010, 2011 • Distinguish hadronic and photonic origin from spectrum at 20 – 30 TeV • CTA tests for UHECR production from multi-TeV emissions (TeV BL Lac) UHECRs g ray injection Murase, Dermer, Takami, Migliori 2011 arXiv:1107.5576 Dermer HEAD, Newport, RI 2011 September 7

  11. Beaming Factors for Neutron Production

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