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We report on X-ray flares that were observed from the active galactic nucleusI Zwicky 1 (I Zw 1) in 2020 January by the NuSTAR and XMM-Newton observatories.The X-ray spectrum is well-described by a model comprised of the continuumemission from the corona and its reflection from the accretion disc around arapidly spinning (a > 0.94) black hole. In order to model the broadbandspectrum, it is necessary to account for the variation in ionisation across thedisc. Analysis of the X-ray spectrum in time periods before, during and afterthe flares reveal the underlying changes to the corona associated with theflaring. During the flares, the reflection fraction drops significantly,consistent with the acceleration of the corona away from the accretion disc. Wefind the first evidence that during the X-ray flares, the temperature dropsfrom 140(-20,+100)keV before to 45(-9,+40)keV during the flares. The profile ofthe iron K line reveals the emissivity profile of the accretion disc, showingit to be illuminated by a compact corona extending no more than 7(-2,+4)rg overthe disc before the flares, but with tentative evidence that the corona expandsas it is accelerated during the flares. Once the flares subsided, the coronahad collapsed to a radius of 6(-2,+2)rg. The rapid timescale of the flaressuggests that they arise within the black-hole magnetosphere rather than in theaccretion disc, and the variation of the corona is consistent with thecontinuum arising from the Comptonisation of seed photons from the disc.

Acceleration and cooling of the corona during X-ray flares from the Seyfert galaxy I Zw 1