Systematic Study of TeV detected BL Lacs: Jet Energetics and Particle Acceleration Efficiency in the Blazar Zone Yoshiyuki Inoue (JAXA International Top Young Fellow) Collaborators: Yasuyuki T. Tanaka
The extreme Universe viewed in very-high-energy gamma-rays 2015, Kashiwa, 2016-01-17

What is AGN jet energetics? • Fermi allows us systematic study • Prad ~ 0.1 Pjet (Ghisellini+'14) • but, only luminous blazars → HBLs: MAXI, BAT, LAT, IACTs • based on phenomenological models: e.g. 12 parameters for Mrk 421. → physically connected parameters.
•  Are AGN jets efficient particle accelerators? •  primary candidates for UHECR acceleration sites. •  But, particle acceleration efficiency is not well understood. • Past SED fittings suggested low efficiency (η~10⁵; Inoue & Takahara '96, Sato+'08, Finke+'08). • But, not simultaneous data and no systematic studies.
Select 36 blazars with z from the default TeVcat catalog. 3FGL SED data. • Low-state data are available for 31/36. •  13 HBLs have BAT data. • CIB correction by YI +'13.
•  One-zone synchrotron self Compton (e.g. Finke+'08) •  Beaming factor “δ” = bulk Lorentz factor “Γ” • Angular size of the blob “θ” = the jet opening angle “θ¡” • Гθ¡ = 1 -> θ = 1/δ •  Assume spherical emitting plasma at r = 1000 rs from BH. • ~1 day variability for Mbh = 10° Msun & δ = 10.
• Assume diffusive shock acceleration. • broken-power law plus hyper-exp cutoff
• It should be p 2 = p 1 + 1. But, photon spectrum steeping can be steeper in inhomogeneous fluid (e.g. Reynolds '09). • By setting p2 as a free parameter, we phenomenologically consider inhomogeneity of the emission region. • cooling break : syn. + SSC cooling = dynamical time. •  maximum Lorentz factor : acc. time = syn. + SSC cooling. •  minimum electron Lorentz factor is set by shocked thermal proton energy.
• Free parameters are • Ke, P1, P2, B, δ, ηg • Global fit to low-state data but not including errors. • Then, perform fit to BAT data including errors setting only η g as a free parameter.
best fit MAXI/GSC Swift/BAT Fermi/LAT IACTs NED YI & Tanaka, in prep.
Electron Distribution Index Relation • Most objects show p 1 ~ 2.2 which is expected for relativistic shocks (e.g. Kirk+’00, Keshet & Waxman ’05, Sironi+’15) • However, p 1 ~1.6 is required for H1426-428. Stochastic acceleration? Some are consistent with homogeneous radiative cooling (p 2 ~ p 1+1), . but others not. Due to inhomogenity in the source?
•  All of our samples are near equipartition: P B ~ 0.1 P e • Assuming cold protons only, radiative efficiency is 0.06. • similar to FSRQ samples (Ghisellini+'14)
• Pjet ~ 10 -3 LEdd • The mass accretion rate of HBLs is about ㎡ 〜 1.2 × 10 –2 (Wang+'02). • ~0.1% of accreted mass loaded on the jet in HBLs. • But, ~100% mass loaded in the case of FSRQs (Ghisellini+'14) • RIAFs inevitably generate outflows ejecting ~30% of mass as a disk wind (Blandford & Begelman '99; Totani '06)
• HBLs are not efficient accelerators having η g ~ 10 4. • We have P b ~ 0.06 P jet . Then, the maximum proton energy 2e f B Pjet can be Ep,max C Ng
Ng [eV]. 104
1ES 0229+200 •  Very hard HBL 3FGL data shows a soft spectrum at GeV band. • this comes from Synchrotron emission? •  A possible contamination: ・Sun & moon occultation?
•  Systematic spectral study of 13 TeV HBLs using MAXI, BAT, LAT, & IACTs data under the DSA scenario. • P B ~ 0.1 P e • Prad ~ 0.06 Pjet similar to FSRQs assuming cold protons only. •  0.1 % of accreted mass is loaded on to the jet. • acceleration efficiency is ηg ~ 104. • But 1ES 0229+200 can have η ~ 1. Caused by Sun & moon occultations?