Absorption Measure Distribution in AGN

TL;DR

This paper investigates the absorption measure distribution (AMD) in AGN X-ray outflows, highlighting how the shape of the ionizing spectral energy distribution significantly affects AMD normalization and modeling accuracy.

Contribution

It demonstrates the impact of the ionizing spectral energy distribution shape on AMD normalization, addressing inconsistencies between observations and models.

Findings

AMD normalization varies by an order of magnitude with SED shape

Constant pressure photoionization models reproduce AMD shape but have normalization issues

Discontinuities in AMD are sensitive to the ionizing spectrum

Abstract

The most common observed feature of the X-ray outflows in active galactic nuclei (AGN) is their broad ionization distribution spanning up to $\sim$ 5 orders of magnitude in ionization levels. This feature is quantified in terms of absorption measure distribution (AMD), defined as the distribution of column density with the ionization parameter. Recently, the photoionization models with constant pressure assumption are shown to well reproduce the observed shape of AMD. However, there exist inconsistencies in the normalization and the position of discontinuities presented in the AMD shape between the observation and model. In this work, we show that AMD normalization differs by one order of magnitude depending on the shape of ionizing spectral energy distribution (SED).