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We report the detection of high-amplitude X-ray flaring of the AGN HE1136-2304, which is accompanied by a strong increase in the flux of the broadBalmer lines, changing its Seyfert type from almost type 2 in 1993 down to 1.5in 2014. HE 1136-2304 was detected by the XMM-Newton slew survey at >10 timesthe flux it had in the ROSAT all-sky survey, and confirmed with Swift follow-upafter increasing in X-ray flux by a factor of 30. Optical spectroscopy withSALT shows that the AGN has changed from a Seyfert 1.95 to a Seyfert 1.5galaxy, with greatly increased broad line emission and an increase in bluecontinuum AGN flux by a factor of > 4. The X-ray spectra from XMM-Newton andNuSTAR reveal moderate intrinsic absorption and a high energy cutoff at 100keV. We consider several different physical scenarios for a flare, such aschanges in obscuring material, tidal disruption events, and an increase in theaccretion rate. We find that the most likely cause of the increased flux is anincrease in the accretion rate, although it could also be due to a change inobscuration.

The detection and X-ray view of the changing look AGN HE 1136-2304