A Study of Warm Absorbers in Active Galactic Nuclei for Variable Ionizing Sources

The nature of the extreme variability of the central ionizing source in active galactic nuclei (AGN) suggests that the outflowing gas may deviate from the commonly approached equilibrium approximation. Hence, we need to consider a time-dependent calculation to describe the ionization states and the transmitted spectra more accurately. To see the effects of the variability quantitatively, we carried out a time-dependent photoionization simulation by solving a time-dependent balance equation for level population, internal energy, and radiative transfer simultaneously and self-consistently and developed a time-dependent photoionization modeling code (TDP code). The outflows responsible for the absorption of the X-rays, also known as warm absorbers, are investigated using this newly developed TDP code for various input parameters such as density, the shape of the incident light curve, SED, etc. We simulated the outflow for step, flare, and sinusoidal incident light curves and will present the results. We analyzed the high-resolution transmitted model spectra to understand how the ionization structure of the outflow changes over time. The study of the time-resolved spectra can potentially be used in constraining the warm absorber properties such as density and, in turn, the location. This will help to understand the AGN feedback by estimating the kinetic power of the outflow.