XMM-Newton RGS observation of the warm absorber in Mrk 279

TL;DR

This study analyzes XMM-Newton observations of Mrk 279 to understand the properties and stability of its warm absorber, finding no significant short-term or long-term changes despite flux variability.

Contribution

It provides the first detailed analysis of the warm absorber's response to flux changes in Mrk 279 using XMM-Newton data, comparing with previous Chandra observations.

Findings

No significant short-term changes in the warm absorber.

No long-term variations detected over 2.5 years.

Absorbing gas likely located near the dusty torus.

Abstract

The Seyfert 1 galaxy Mrk 279 was observed by XMM-Newton in November 2005 in three consecutive orbits, showing significant short-scale variability (average soft band variation in flux ~20%). The source is known to host a two-component warm absorber with distinct ionisation states from a previous Chandra observation. We aim to study the warm absorber in Mrk 279 and investigate any possible response to the short-term variations of the ionising flux, and to assess whether it has varied on a long-term time scale with respect to the Chandra observation. We find no significant changes in the warm absorber on neither short time scales (~2 days) nor at longer time scales (two and a half years), as the variations in the ionic column densities of the most relevant elements are below the 90% confidence level. The variations could still be present but are statistically undetected given the signal-to-noise ratio of the data. Starting from reasonable standard assumptions we estimate the location of the absorbing gas, which is likely to be associated with the putative dusty torus rather than with the Broad Line Region if the outflowing gas is moving at the escape velocity or larger.