Dev R Sadaula

I am a postdoctoral research associate at NASA Goddard Space Flight Center. My research primarily focuses on modeling active galactic nuclei (AGN) outflow. The outflow that causes absorption in X-rays is known as a "warm absorber" (WA). The modeling of these absorbers is often done considering the photoionization equilibrium approximation. However, this assumption is somewhat simplified, and time-dependent effects are crucial for some astrophysical objects where the ionizing radiation field or dynamics change rapidly, particularly in the case of WA, where X-rays emanating from the central region of the AGN are often highly variable. Hence, I have developed a computational tool to model such photo-ionized plasma, incorporating its time-dependent effects. This code quantitatively calculates the physical properties of WAs, such as temperature and ionization state and their evolution, and produces a transmitted model spectrum. In addition, the variability study could be used as a density diagnostic of WAs in AGN, which is then used to determine the location. Time-dependent photoionization is, however, important where different scales of variability exist.