IR lines of AGNs accretion disk

The soft state would include broad-line Seyferts and about half of the Seyfert 2 population, showing highly excited gas and radio-quiet cores consistent with disc-dominated nuclei, in agreement with previous studies. The hard state mostly includes low-luminosity AGN (<= 10-3^ LEdd) characterized by low-excitation radio-loud nuclei and a negligible disc contribution. The remaining half of Seyfert 2 nuclei and the bright LINERs show low excitation at high accretion luminosities and could be identified with the bright hard and intermediate states.

Their hosts show ongoing star formation in the central kiloparsecs. We discuss the above scenario, its potential links with the galaxy evolution picture, and the possible presence of accretion state transitions in AGN, as suggested by the growing population of changing-look quasars.