Does the Jet Production Efficiency of Radio Galaxies Control Their Optical AGN Types?

TL;DR

This study investigates how the efficiency of jet production in radio galaxies varies with optical AGN types, revealing a potential evolutionary sequence and suggesting a tighter intrinsic relation between accretion power and jet power.

Contribution

It demonstrates that jet production efficiency depends on AGN type, indicating an evolutionary sequence and refining the understanding of the P_B-P_jet relation.

Findings

Seyfert 2 galaxies are less efficient in jet production than Seyfert 1s and LINERs.

The jet efficiency difference suggests an evolutionary sequence from Sy2s to Sy1s and LINERs.

The intrinsic P_B-P_jet relation may be tighter than previously thought.

Abstract

The jet production efficiency of radio galaxies can be quantified by comparison of their kinetic jet powers P_jet and Bondi accretion powers P_B. These two parameters are known to be related linearly, with the jet power resulting from the Bondi power by multiplication with an efficiency factor of order 1%. Using a recently published (Nemmen + Tchekhovskoy 2014) high-quality sample of 27 radio galaxies, I construct a P_B-P_jet diagram that includes information on optical AGN types as far as available. This diagram indicates that the jet production efficiency is a function of AGN type: Seyfert 2 galaxies seem to be systematically (with a false alarm probability of 0.043%) less efficient, by about one order of magnitude, in powering jets than Seyfert 1 galaxies, LINERs, or the remaining radio galaxies. This suggests an evolutionary sequence from Sy2s to Sy1s and LINERs, controlled by an interplay of jets on the one hand and dust and gas in galactic nuclei on the other hand. When taking this effect into account, the P_B-P_jet relation is probably much tighter intrinsically than currently assumed.