The Changing-Look Quasar Mrk 590 is Awakening
  Mrk 590 was originally classified as a Seyfert 1 galaxy, but then it
underwent dramatic changes: the nuclear luminosity dropped by over two orders
of magnitude and the broad emission lines all but disappeared from the optical
spectrum. Here we present followup observations to the original discovery and
characterization of this "changing look" active galactic nucleus (AGN). The new
Chandra and HST observations from 2014 show that Mrk 590 is awakening, changing
its appearance again. While the source continues to be in a low state, its soft
excess has re-emerged, though not to the previous level. The UV continuum is
brighter by more than a factor of two and the broad MgII emission line is
present, indicating that the ionizing continuum is also brightening. These
observations suggest that the soft excess is not due to reprocessed hard X-ray
emission. Instead, it is connected to the UV continuum through warm
Comptonization. Variability of the Fe K-alpha emission lines suggests that the
reprocessing region is within about 10 light years or 3 pc of the central
source. The AGN type change is neither due to obscuration, nor due to one-way
evolution from type-1 to type-2, as suggested in literature, but may be related
to episodic accretion events.
