Speaker
Description
Offsets between the Brightest Cluster Galaxy (BCG) and the gravitational potential minimum in relaxed galaxy clusters, known as a “BCG wobble”, provide a smoking-gun signature of dark matter self-interactions. Our previous work shows that such self-interactions can produce a wobble with an amplitude of ~5 kpc in massive clusters - requiring exquisitely accurate and precise modelling. In order to measure this using strong lensing data from HST and JWST we propose a new proxy. We analyse the offsets in two dimensions within a physically motivated coordinate frame to break the degeneracy between physical offsets and systematic errors in centroiding, leading to an order of magnitude greater sensitivity. In this talk, I demonstrate the effectiveness of this method using mock strong lensing data from simulated clusters, and present preliminary results for observed systems.