The Impact of Accurate Extinction Measurements for X-ray Spectral Models

TL;DR

This paper develops a new spectral model for X-ray extinction that incorporates dust scattering, enabling more accurate interpretation of X-ray spectra and their relation to UV/optical extinction.

Contribution

It introduces a convolution-based scattering model for X-ray spectral fitting tools, bridging the gap between absorption and scattering effects in interstellar extinction modeling.

Findings

The model accounts for dust scattering effects in X-ray spectra.

It allows for consistent extinction modeling across X-ray and UV/optical wavelengths.

Application demonstrates improved spectral fit accuracy.

Abstract

Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources and the impact on an observed source spectrum can be significant, if modest, compared to direct absorption. By convolving the scattering cross section with dust models, we have created a spectral model as a function of energy, type of dust, and extraction region that can be used with models of direct absorption. This will ensure the extinction model is consistent and enable direct connections to be made between a source's X-ray spectral fits and its UV/optical extinction.