Thermal Instabilities in the Wind of NGC 3783

Abstract

Outflows in Active Galactic Nuclei (AGN) play an important role in the evolution of their host galaxy and on the enrichment of the intergalactic medium. In the X‐ray range, the outflows appear as a warm absorber (WA) gas displaying high bulk velocities.The Absorption Measure Distribution (AMD) method provides a new handle on constraining the physics of the WA. Here, we report on the theoretical interpretation of an AMD analysis of the Seyfert galaxy NGC 3783. Computations in constant total pressure performed with the transfer‐photoionization code TITAN allow us to reproduce the WA gas ionic column‐densities by adjusting some important plasma parameters, e.g., the ionization parameter (ξ), the total column density (NH) or the amount of micro‐turbulence.Results from both the AMD method and the TITAN code suggest the presence of a region where thermal instabilities are observed. This is compatible with the hypothesis of the WA being a clumpy, two‐phase medium with colder, dense clouds embedded in a hotter, diffuse gas.