The bluest changing-look QSO SDSS J224113-012108
  In this manuscript, we report a new changing-look QSO (CLQSO) SDSS J2241 at
$z=0.059$. Based on the multi-epoch SDSS spectra from 2011 to 2017, the flux
ratio of broad H$\alpha$ to broad H$\beta$ has been changed from 7\ in 2011 to
2.7\ in 2017, leading SDSS J2241 with spectral index
$\alpha_\lambda\sim-5.21\pm0.02$ ($\lambda< 4000$\AA) in 2017 to be so-far the
bluest CLQSO. Based on the SDSS spectrum in 2011, the host galaxy contributions
with stellar velocity dispersion $\sim86{\rm km/s}$ can be well determined,
leading to the M-sigma relation expected central BH mass $\sim3\times10^6{\rm
M_\odot}$. However, through properties of the broad H$\alpha$, the virial BH
mass is $\sim10^8{\rm M_\odot}$, about two magnitudes larger than the mass
through the M-sigma relation. The different BH masses through different methods
indicate SDSS J2241 is one unique CLQSO. Meanwhile, the long-term photometric
light curve shows interesting variability properties, not expected by DRW
process commonly applied in AGN but probably connected to a central TDE.
Furthermore, based on continuum emission properties in 2017 with no dust
obscurations, only considering the moving dust clouds cannot be preferred to
explain the CLQSO SDSS J2241, because the expected intrinsic reddening
corrected continuum emissions were unreasonably higher than the unobscured
continuum emissions in 2017.
