Abstract

We present the drastic transformation of the X-ray properties of the active galactic nucleus (AGN) 1ES 1927+654, following a changing-look event. After the optical/ultraviolet outburst the power-law component, produced in the X-ray corona, disappeared, and the spectrum of 1ES 1927+65 instead became dominated by a blackbody component (kT similar to 80-120 eV). This implies that the X-ray corona, ubiquitously found in AGNs, was destroyed in the event. Our dense similar to 450 days long X-ray monitoring shows that the source is extremely variable in the X-ray band. On long timescales the source varies up to similar to 4 dex in similar to 100 days, while on short timescales up to similar to 2 dex in similar to 8 hr. The luminosity of the source is found to first show a strong dip down to similar to 10(40) erg s(-1), and then a constant increase in luminosity to levels exceeding the pre-outburst level greater than or similar to 300 days after the optical event detection, rising up asymptotically to similar to 2 x 10(44) erg s(-1). As the X-ray luminosity of the source increases, the X-ray corona is recreated, and a very steep power-law component (Gamma similar or equal to 3) reappears, and dominates the emission for 0.3-2 keV luminosities greater than or similar to 10(43.7) erg s(-1), similar to 300 days after the beginning of the event. We discuss possible origins of this event, and speculate that our observations could be explained by the interaction between the accretion flow and debris from a tidally disrupted star. Our results show that changing-look events can be associated with dramatic and rapid transformations of the innermost regions of accreting supermassive black holes.