Impact of straylight on the Science Objectives of SWG3.2

This document provides a preliminary assessment of the impact of stray light on the level-1 science objectives of SWG 3.2 Star formation and Evolution.
Stray light is due to X-ray sources located outside the nominal field of view of the Wolter I mirrors and arises from single reflections on the 2nd mirror surface. The stray light hence reaches the focal plane unfocused producing a pattern that reflects the geometry of the mirror modules. Given the limited size of the X-IFU field of view and the fact that the impact of stray light from sources outside the FoV is lowest on-axis, observations with the X-IFU should be less affected than those using the WFI.
The majority of the targets related to the science objectives of SWG 3.2 that are either in the mock observing plan or are likely to become targets for Athena are located in star forming regions or open clusters in or near the Galactic plane. Stray X-rays will thus mainly come from bright point-like X-ray sources such as low-mass and high-mass X-ray binaries.