An X-ray and optical spectral study of the changing-look narrow-line Seyfert 1 2MASX J0413-0050

Changing-look (CL) active galactic nuclei (AGN) exhibit dramatic spectral and flux variations, caused by changes in the accretion rate (changing-state, CS-AGN) or in the line-of-sight column density (changing-obscuration, CO-AGN). Here I present J0413-0050, initially identified as a narrow-line Seyfert 1 (NLS1) galaxy, which was observed in 2004 and again in 2021, showing the complete disappearance of the Hß line. A third observation confirmed the absence of Hß and the broad Ha component, along with a significant decrease in the continuum level. Meanwhile, the X-ray flux increased across 3 observations spanning a decade, with a particularly notable spike (2 dex higher) in the most recent spectrum. A new optical spectrum then revealed the reappearance of both the narrow Hß and the broad components of Hß and Ha. J0413-0050 may have experienced several switch-on/switch-off phases, with an unknown timescale, potentially affecting the accretion power and thus the optical continuum and the emission lines coming from the broad-line region (BLR). In this talk, I explore all the possible scenarios that could explain these unpredictable variations including CS-AGN behaviour, disc wind or clumpy medium obscuring the BLR, or even BLR 'holidays'. New simultaneous optical/X-rays data I obtained may confirm one of these hypotheses. However, the case of J0413-0050 validates the idea that even highly accreting NLS1s can experience CL phenomena.