STRAY19: the effects of stray-light on source detection and flux determination in a typical Athena WFI observation relevant to the Science Objectives of SWG3.2

In February 2016, the Athena Working Groups and Topical Panels assessed the impact of X-ray stray light on the Athena science. Since then, the baseline configuration of the Athena mirrors has changed. The cost-constrained reduction of the number of mirror rows from 20 to 15 (current baseline) notably led to an increase of the stray-to-image effective area ratio. The impact of stray light could be reduced via the implementation of a dedicated baffle. ASST thus asked the Working Groups and Topical Panels to assess the scientific benefits of a stray light baffle in the framework of the so-called STRAY19 exercise.
The present document provides an assessment of the quantitative benefits of a stray light baffle on the level-1 science objectives of SWG 3.2 Star formation and Evolution, for the case of a typical WFI dithered observation. This document therefore supersedes the previous TN from SWG 3.2 on this subject and it is the companion of the TN “STRAY19: assessment of the benefits of a stray light baffle on the Science Objectives of SWG3.2”. Hereafter, we compare a 100% efficient baffle (resulting in no stray light contamination) with the currently estimated level of stray light corresponding to the 15 row mirror as requested by ASST.