Mergers and interactions in SDSS type 2 quasars at z~0.3-0.4. SDSS J143027.66-005614.8: a case study

TL;DR

This study analyzes the morphological features of 58 SDSS type 2 quasars at z~0.3-0.4, revealing that most host galaxies are ellipticals and many show signs of mergers or interactions, highlighting their role in quasar activity.

Contribution

It provides a comprehensive morphological analysis of a large sample of type 2 quasars, emphasizing the prevalence of mergers and interactions in their host galaxies, including detailed case study of SDSS J143027.66-005614.8.

Findings

Most host galaxies are ellipticals.

Over 59% show signs of mergers or interactions.

The case study supports merger-driven quasar activation.

Abstract

We present a compilation of HST images of 58 luminous SDSS type 2 AGNs at 0.3<z<0.4. 42 of them are type 2 quasars, which are a good representation of all optically selected SDSS type 2 quasars in this range. We find that the majority of the host galaxies are ellipticals (30/42 or 71%). This is consistent with studies of radio loud and radio quiet type 1 quasars which show that their host galaxies are in general ellipticals. A significant fraction of type 2 quasars (>25/42 or >59%) show clear signatures of morphological disturbance which are in most cases identified with merger/interaction processes. We discuss this in the context of related works on type 2 quasars and powerful radio galaxies. We study in detail the particular case of the radio quiet type 2 quasar SDSS J143027.66-005614.8 at z=0.32 based on VLT, HST and SDSS imaging and spectroscopic data. We discuss the global properties of the object in the context of theoretical and observational studies of galaxy mergers/interactions and their role in the triggering of the nuclear and star formation activities in the most luminous active galaxies.