Dielectronic recombination and stability of warm gas in AGN

TL;DR

This paper investigates how updated dielectronic recombination rates affect the thermal stability and physical predictions of warm absorbers in active galactic nuclei, revealing increased stability and multiphase potential.

Contribution

It introduces new stability curve calculations using recent dielectronic recombination rates, showing significant differences from previous models and improving reliability.

Findings

Higher probability of thermally stable warm absorbers at 10^5 K.

Greater likelihood of multiphase warm absorber structures.

More reliable models due to use of current recombination rate data.

Abstract

Understanding the thermal equilibrium (stability) curve may offer insights into the nature of the warm absorbers often found in active galactic nuclei. Its shape is determined by factors like the spectrum of the ionizing continuum and the chemical composition of the gas. We find that the stability curves obtained under the same set of the above mentioned physical factors, but using recently derived dielectronic recombination rates, give significantly different results, especially in the regions corresponding to warm absorbers, leading to different physical predictions. Using the current rates we find a larger probability of having thermally stable warm absorber at $10^5 \kel$ than previous predictions and also a greater possibility for its multiphase nature. the results obtained with the current dielectronic recombination rate coefficients are more reliable because the warm absorber models along the stability curve have computed coefficient values, whereas previous calculations relied on guessed averages for the same due to lack of available data.