Near-infrared extinction with discretised stellar colours

TL;DR

This paper introduces a new method for creating near-infrared extinction maps using discretised stellar colours, which performs well under certain conditions and offers advantages over existing methods like NICER.

Contribution

The paper presents a novel discretised colour distribution approach for NIR extinction mapping, improving accuracy with prior information and handling complex colour distributions.

Findings

Performs comparably to NICER with large photometric errors

Advantages when intrinsic colour distribution is complex

Enhanced accuracy with prior small-scale structure knowledge

Abstract

Several methods exist to convert near-infrared (NIR) stellar observations into extinction maps. We present a new method based on NIR multiband observations. The method uses a discretised version of the distribution of intrinsic stellar colours. A number of variations of the basic method are tested, and the results are compared to NICER calculations. When photometric errors are large, the results are close to those of NICER method but some advantages can be seen when the distribution of intrinsic colours cannot be described well with a single covariance matrix. A priori information about relative column density variations at sub-beam scales can result in a significant increase in accuracy. The results may be further improved by considering the magnitude dependence of the intrinsic colours. Thus, the new methods are useful mostly when photometric errors are small, the distribution of intrinsic colours is well known, or one has prior knowledge of the small-scale structures.