Copyright © 2018, Oxford University PressUrbano Mayorgas, J. J.Villar Martín, M.Buitrago, F.Piqueras López, J.Rodríguez del Pino, B.Koekemoer, A. M.Huertas Company, M.Domínguez Tenreiro, R.Carrera, F. J.Tadhunter, C.2021-04-142021-04-142019-02-28Monthly Notices of the Royal Astronomical Society 483(2): 1829–1849(2019)0035-8711https://academic.oup.com/mnras/article/483/2/1829/5145863http://hdl.handle.net/20.500.12666/369We study the morphological and structural properties of the host galaxies associated with 57 optically selected luminous type 2 active galactic nuclei (AGNs) at z ∼ 0.3–0.4: 16 high-luminosity Seyfert 2 [HLSy2, 8.0 ≤ log(⁠L[OIII]/L⊙)< 8.3] and 41 obscured [QSO2, log(⁠L[OIII]/L⊙)≥ 8.3] quasars. With this work, the total number of QSO2s at z < 1 with parametrized galaxies increases from ∼35 to 76. Our analysis is based on Hubble Space Telescope WFPC2 and ACS images that we fit with GALFIT. HLSy2s and QSO2s show a wide diversity of galaxy hosts. The main difference lies in the higher incidence of highly disturbed systems among QSO2s. This is consistent with a scenario in which galaxy interactions are the dominant mechanism triggering nuclear activity at the highest AGN power. There is a strong dependence of galaxy properties with AGN power (assuming L[OIII] is an adequate proxy). The relative contribution of the spheroidal component to the total galaxy light (B/T) increases with L[OIII]⁠. While systems dominated by the spheroidal component spread across the total range of L[OIII]⁠, most disc-dominated galaxies concentrate at log(⁠L[OIII]/L⊙)<8.6. This is expected if more powerful AGNs are powered by more massive black holes which are hosted by more massive bulges or spheroids. The average galaxy sizes (〈re〉) are 5.0 ± 1.5 kpc for HLSy2s and 3.9 ± 0.6 kpc for HLSy2s and QSO2s, respectively. These are significantly smaller than those found for QSO1s and narrow-line radio galaxies at similar z⁠. We put the results of our work in the context of related studies of AGNs with quasar-like luminosities.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttps://creativecommons.org/licenses/by-nc-nd/4.0/Galaxies: activeGalaxies: evolutionQuasars: generalinfo:eu-repo/semantics/article10.1093/mnras/sty29101365-2966http://dx.doi.org/10.13039/501100003329http://dx.doi.org/10.13039/501100001871http://dx.doi.org/10.13039/501100011033info:eu-repo/semantics/openAccess