Interactions, star formation and extended nebulae in SDSS type 2 quasars
  at 0.3<~ z <~ 0.6
  We present long-slit spectroscopy and imaging data obtained with FORS2 on the
Very Large Telescope of 13 optically selected type 2 quasars at z~0.3-0.6 from
the original sample of Zakamska et al. (2003). The sample is likely to be
affected by different selection biases. We investigate the evidence for: a)
mergers/interactions b) star formation activity in the neighborhood of the
quasars and c) extended emission line regions and their nature. Evidence for
mergers/interactions is found in 5/13 objects. This is a lower limit for our
sample, given the shallowness of most of our continuum images. Although AGN
photoionization cannot be totally discarded, line ratios consistent with
stellar photoionization are found in general in companion galaxies/knots/nuclei
near these same objects. On the contrary, the gas in the neighborhood of the
quasar nucleus shows line ratios inconsistent with HII galaxies and typical of
AGN photoionized nebulae. A natural scenario to explain the observations is
that star formation is ongoing in companion galaxies/knots/nuclei, possibly
triggered by the interactions. These systems are, therefore, composite in their
emission line properties showing a combination of AGN and star formation
features.
  Extended emission line regions (EELRs) have been found in 7/13 objects,
although this fraction might be higher if a complete spatial coverage around
the quasars was performed. The sizes vary between few and up to 64 kpc. In
general, the EELRs apparently consist of an extended nebula associated with the
quasar. In at least one case the EELR is associated with ionized tidal
features.
