Variable X-ray Absorption toward Gravitationally-Lensed Blazar PKS1830-211

TL;DR

This study analyzes X-ray observations of the gravitationally-lensed blazar PKS1830-211, revealing variable intrinsic absorption likely caused by outflows or jet-environment interactions, and rules out microlensing as the cause.

Contribution

It demonstrates that the observed X-ray absorption variability is intrinsic to the blazar and provides insights into the outflows and jet interactions in AGNs.

Findings

Absorption varies with amplitudes of 2-30e22 cm^-2.

Variable absorption is likely intrinsic, not due to lens or microlensing.

Supports models of outflows from the central engine.

Abstract

We present X-ray spectral analysis of five Chandra and XMM-Newton observations of the gravitationally-lensed blazar PKS1830-211 from 2000 to 2004. We show that the X-ray absorption toward PKS1830-211 is variable, and the variable absorption is most likely to be intrinsic with amplitudes of about 2-30e22 cm^-2 depending on whether or not the absorber is partially covering the X-ray source. Our results confirm the variable absorption observed previously, although interpreted differently, in a sequence of ASCA observations. This large variation in the absorption column density can be interpreted as outflows from the central engine in the polar direction, consistent with recent numerical models of inflow/outflows in AGNs. In addition, it could possibly be caused by the interaction between the blazar jet and its environment, or the variation from the geometric configuration of the jet. While the spectra can also be fitted with a variable absorption at the lens redshift, we show that this model is unlikely. We also rule out the simple microlensing interpretation of variability which was previously suggested.