Self-interactions of dark matter particles can potentially lead to an observable separation between the dark matter halo and the stars of a galaxy moving through a region of large dark matter density. Such a separation has recently been observed in a galaxy falling into the core of the galaxy cluster Abell 3827. We estimated the DM self-interaction cross section needed to reproduce the observed effects and find that the sensitivity of Abell 3827 has been significantly overestimated in a previous study. Our corrected estimate is σ~/mDM∼3cm2g−1 when self-interactions result in an effective drag force and σ/mDM∼1.5cm2g−1 for the case of contact interactions, in some tension with previous upper bounds.
@article{arxiv.1504.06576,
title = {On the interpretation of dark matter self-interactions in Abell 3827},
author = {Felix Kahlhoefer and Kai Schmidt-Hoberg and Janis Kummer and Subir Sarkar},
journal= {arXiv preprint arXiv:1504.06576},
year = {2015}
}