Possible γ-ray emission of radio intermediate AGN III Zw 2 and its implication on the evolution of jets in AGNs

Abstract

AGNs with hard γ-ray emission identified so far are radio-loud. III Zw 2 is a radio intermediate AGN with a relativistic jet. We study its spectral energy distribution (SED) and find that the broad band emissions are dominated by the non-thermal emissions from the jet. We model its SED through a synchrotron + inverse Compton (IC) model. The results show that the IC component of III Zw 2 peaks at a few MeV, and the flux density drops rapidly at higher energy with photon index Γ ≈ 3.3 above 0.1 GeV. The predicted flux is slightly over the sensitivity of Fermi/LAT, but it was not included in the first Fermi/LAT AGN catalog. The reason for this may be: 1) that the IC peak is low and the spectrum is very steep above 0.1 GeV, 2) that III Zw 2 is in the low state during the period of the Fermi/LAT operation. We also find that III Zw 2 follows similar jet processes as those in γ-ray AGNs, e.g., the relation between jet power and radiation power, which is called the blazar sequence. We suggest that III Zw 2 may be a young source at an earlier stage of jet activity.