# An X-ray spectral variability of fast disk winds in AGN

## TL;DR

This study develops a 3D Monte Carlo spectral model for fast AGN disk winds, explaining observed absorption line variability as changes in wind angle rather than outflow rate, indicating wind stability.

## Contribution

The paper introduces a new 3D Monte Carlo spectral model for AGN disk winds, linking absorption variability to wind geometry changes rather than mass outflow fluctuations.

## Key findings

- Absorption line variability is due to wind angle changes.
- Fast disk winds are stable over time.
- The model successfully reproduces observed spectral features.

## Abstract

Recent X-ray observations of blue-shifted absorption lines revealed an existence of the extremely fast disk winds with outflow velocities of ~0.1-0.3c. Such fast outflows would have a large impact on the coevolution of black holes and host galaxies since they are expected to carry a large amount of kinetic energy. One of the common characteristics of these fast winds is a strong time variability of the absorption feature. To investigate this variability, we have developed a new X-ray spectral model of the disk winds, which is generated by 3-dimensional Monte Carlo radiation transfer simulations on the assumption of the realistic wind geometry. By applying our wind model to the multi-epoch X-ray data of an archetypal wind source PDS 456, we find the variability in the absorption line is explained by a change of the wind outflowing angle without any large variability in the mass outflow rate of the wind. This result indicates that the fast disk winds are stable and that local hydrodynamic instabilities produce a large time variability of the absorption line. Moreover, we also apply our wind model to the disk-line source 1H 0707-495. The characteristic Fe-K feature in this source is successfully reproduced our disk wind model for all the observations.