Density calculations of NGC 3783 warm absorbers using a time-dependent photoionisation model

Abstract

Outflowing wind, as one type of AGN feedback involving non-collimated ionised winds such as those prevalent in Seyfert-1 AGNs, impacts the host galaxy by carrying kinetic energy outwards. However, the distance of the outflowing wind is poorly constrained because of a lack of direct imaging observations, which limits our understanding of its kinetic power, and thus of its impact on the local galactic environment. One potential approach to solving this problem involves determination of the density of the ionised plasma, making it possible to derive the distance using the ionisation parameter ξ, which can be measured based on the ionisation state. Here, by applying a new time-dependent photoionisation model, tpho, in SPEX, we define a new approach, the tpho-delay method, which we use to calculate or predict a detectable density range for warm absorbers of NGC 3783. The tpho model solves self-consistently the time-dependent ionic concentrations, which enables us to study the delayed states of the plasma in detail. We show that it is crucial to model the non-equilibrium effects accurately for the delayed phase, where the non-equilibrium and equilibrium models diverge significantly. Finally, we calculate the crossing time to consider the effect of the transverse motion of the outflow on the intrinsic luminosity variation. Future spectroscopic observations with more sensitive instruments are expected to provide more accurate constraints on the outflow density, and therefore on the feedback energetics.