Variable X-ray reflection from 1H~0419--577

TL;DR

This study analyzes X-ray spectral variability in the Seyfert 1 galaxy 1H~0419--577, comparing multiple observations with physical models, and finds that blurred reflection best explains the data and variability patterns.

Contribution

It demonstrates that blurred reflection models best fit the spectral data and variability, challenging partial covering absorption models and highlighting the importance of disk-corona geometry changes.

Findings

Blurred reflection model provides the best fit to all observations.

Soft X-ray excess and iron line variability suggest reflection origin.

Spectral variability indicates changes in accretion disk and corona geometry.

Abstract

We present detailed broadband X-ray spectral variability of a Seyfert 1 galaxy 1H~0419--577 based on an archival \suzaku{} observation in July 2007, a new \suzaku{} observation performed in January 2010 and the two latest \xmm{} observations from May 2010. All the observations show soft X-ray excess emission below $2\kev$ and both \suzaku{} observations show a hard X-ray excess emission above $10\kev$ when compared to a power-law. We have tested three physical models -- a complex partial covering absorption model, a blurred reflection model and an intrinsic disk Comptonization model. Among these three models, the blurred reflection model provided statistically the best-fit to all the four observations. Irrespective of the models used, the soft X-ray excess emission requires contribution from a thermal component similar to that expected from an accretion disk. The partial covering absorption model results in a nonphysical high temperature ($kT_{in} \sim 100\ev$) for an accretion disk and is also statistically the worst fit among the three models. 1H~0419--577 showed remarkable X-ray spectral variability. The soft X-ray excess and the power-law both became weaker in January 2010 as well as in May 2010. A moderately broad iron line, detected in July 2007, is absent in the January 2010 observation. Correlated variability of the soft X-ray excess and the iron $K\alpha$ line strongly suggest reflection origin for both the components. However, such spectral variability cannot be explained by the light bending model alone and requires changes in the accretion disk/corona geometry possibly arising from changes in the accretion rate.