2025A&A...694A.302L

We reanalyse the Chandra/HETGS observations of NGC 3783 from the campaign in the year 2001 and identify significant spectral variations in the Fe unresolved transition array (UTA) over timescales of weeks to months. These changes correlate with a 1.4- to two-fold increase in the ionising continuum and exceed 10σ significance. The variations primarily originate from a low-ionisation state (log ξ = 1.65) component of the warm absorber. Time-dependent photoionisation modelling confirmed the sensitivity of this low-ionisation component to continuum variations within the Fe UTA band. Local fitting indicated a lower density limit of > 10^12.3 m^–3 at a 3σ statistical uncertainty, with the component located within 0.27 pc. Our findings suggest that this low-ionisation component is a potential failed wind candidate.