X-Ray Absorption Analysis of MCG-6-30-15: Discerning Three Kinematic Systems

TL;DR

This study analyzes the X-ray spectrum of MCG-6-30-15 to identify three distinct kinematic absorption systems, revealing detailed ionization structures and local gas contributions, and refining spectral line wavelengths.

Contribution

It is the first to distinguish three kinematic absorption systems in MCG-6-30-15 and reconstructs their ionization and spatial properties using high-resolution X-ray spectroscopy.

Findings

Identified three absorption systems: two outflows and one local gas.

Reconstructed the absorption measure distribution spanning five orders of magnitude.

Estimated the fast outflow's location within 11 light days of the AGN.

Abstract

By analyzing the X-ray spectrum of MCG-6-30-15 obtained with the HETG spectrometer on board the Chandra Observatory, we identify three kinematically distinct absorption systems; two outflow components intrinsic to MCG-6-30-15, and one local at z = 0. The slow outflow at -100 +/- 50 km s^-1 has a large range of ionization manifested by absorption from 24 different charge states of Fe, which enables a detailed reconstruction of the absorption measure distribution (AMD). This AMD spans five orders of magnitude in ionization parameter: -1.5 < log xi < 3.5 (cgs units), with a total column density of N_H = (5.3 +/- 0.7) x 10^21 cm^-2. The fast outflow at -1900 +/- 150 km s^-1 has a well defined ionization parameter with log xi = 3.82 +/- 0.03 (cgs units) and column density N_H = 8.1 +/- 0.7 x 10^22 cm^-2. Assuming this component is a thin, uniform, spherical shell, it can be estimated to lie within 11 light days of the \agn center. The third component, most clearly detected in the lower oxygen charge states O^+1 - O^+6, has been confused in the past with the fast outflow, but is identified here with local gas z = 0 and a total column density N_H of a few 10^20 cm^-2. Finally, we exploit the excellent spectral resolution of the HETGS and use the present spectrum to determine the rest-frame wavelengths of oxygen inner-shell lines that were previously uncertain.