Long-term X-ray stability and UV variability of the ionized absorption in NGC 3783

TL;DR

This study analyzes long-term X-ray and UV observations of NGC 3783, revealing stable X-ray absorption, significant UV flux reduction, and kinematic changes in UV absorbers over 12 years, with implications for AGN outflow dynamics.

Contribution

It provides the first long-term comparison of X-ray and UV absorption features in NGC 3783, highlighting the stability of X-ray absorbers and kinematic variability in UV absorbers.

Findings

No significant change in X-ray absorber properties.

Approximately 40% decrease in UV and X-ray flux.

Kinematic deceleration observed in UV absorbers.

Abstract

We present the results of recent Chandra High-Energy Transmission Grating Spectrometer and Hubble Space Telescope Cosmic Origins Spectrograph observations of the nearby Seyfert 1 galaxy NGC 3783 which shows a strong, non-varying X-ray warm absorber and physically related and kinematically varying UV absorption. We compare our new observations to high-resolution, high signal-to-noise archival data from 2001, allowing a unique investigation into the long-term variations of the absorption over a 12 yr period. We find no statistically significant changes in the physical properties of the X-ray absorber, but there is a significant drop of ~40% in the UV and X-ray flux, and a significant flattening of the underlying X-ray power-law slope. Large kinematic changes are seen in the UV absorbers, possibly due to radial deceleration of the material. Similar behavior is not observed in the X-ray data, likely due to its lower velocity resolution, which shows an outflow velocity of v ~ -655 km/s in both epochs. The narrow iron K-alpha emission line at 6.4 keV shows no variation between epochs, and its measured width places the material producing the line at a radial distance of ~0.03 pc from the central black hole.