SDSS J075101.42+291419.1: A Super-Eddington Accreting Quasar with Extreme X-ray Variability

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We report the discovery of extreme X-ray variability in a type 1 quasar: SDSS J$075101.42+291419.1$.

• It has a black hole mass of $1.6\times 10^7~\rm M_\odot$ measured from reverberation mapping (RM), and the black hole is accreting with a super-Eddington accretion rate.
• Its XMM-Newton observation in 2015 May reveals a flux drop by a factor of $\sim 22$ with respect to the Swift observation in 2013 May when it showed a typical level of X-ray emission relative to its UV/optical emission.
• The lack of correlated UV variability results in a steep X-ray-to-optical power-law slope ($\alpha_{\rm OX}$) of -1.97 in the low X-ray flux state, corresponding to an X-ray weakness factor of 36.2 at rest-frame 2 keV relative to its UV/optical luminosity.