The evolution of the warm absorber reveals a shocked outflow in the narrow line Seyfert 1 galaxy IRAS 17020+4544

TL;DR

This study analyzes XMM-Newton spectra of IRAS 17020+4544 over 10 years, revealing a complex, multi-phase warm absorber and a shocked outflow, providing insights into AGN feedback mechanisms.

Contribution

It confirms the presence of a four-layer ionized warm absorber and interprets its variability as evidence of a shocked outflow in a Seyfert galaxy.

Findings

Four layers of ionized gas in the warm absorber.

Significant velocity and ionization variations over 10 years.

Evidence supporting a shocked outflow model.

Abstract

We present the analysis of grating spectra of the Narrow Line Seyfert 1 Galaxy IRAS 17020+4544 observed by XMM-Newton in 2004 and 2014. In a previous work on these data, we reported the discovery of a multi-component ultra-fast outflow that is capable of producing feedback in the host galaxy. We also reported the presence of a slow, multi-phase warm absorber. In this follow-up paper, we confirm that this low velocity absorber can be modeled by four layers of ionized gas. When crossing our line-of-sight, this gas presents peculiar changes along the 10-yr time scale elapsed between the two observations obtained by XMM-Newton. While two of such components are almost stationary, the other two are found inflowing and outflowing with significant variations in velocity and ionization between 2004 and 2014. The luminosity and spectral shape of the central source remain practically unvaried. We propose that the presence of the fast wind and of the variable warm absorber can be interpreted in the framework of a `shocked outflow', where the peculiar variability pattern of the low-velocity components might arise from instabilities in the shocked gas.