Understanding extreme quasar optical variability with CRTS: II.
  Changing-state quasars
  We present the results of a systematic search for quasars in the Catalina
Real-time Transient Survey exhibiting both strong photometric and spectroscopic
variability over a decadal baseline. We identify 73 sources with specific
patterns of optical and mid-IR photometric behavior and a defined spectroscopic
change. These "Changing-State" quasars (CSQs) form a higher luminosity sample
to complement existing sets of "Changing-Look" AGN and quasars in the
literature. The CSQs (by selection) exhibit larger photometric variability than
the CLQs. The spectroscopic variability is marginally stronger in the CSQs than
CLQs as defined by the change in H$\beta$/[OIII] ratio. We find 36 sources with
declining H$\beta$ flux, 37 sources with increasing H$\beta$ flux and discover
seven sources with $z > 0.8$, further extending the redshift arm. Our CSQ
sample compares to the literature CLQ objects in similar distributions of
H$\beta$ flux ratios and differential Eddington ratios between high (bright)
and low (dim) states. Taken as a whole, we find that this population of extreme
varying quasars is associated with changes in the Eddington ratio and the
timescales imply cooling/heating fronts propagating through the disk.
