Detecting Ultra-Diffuse Galaxies through their Globular Clusters by Point Process Model

Metro Toronto Convention Centre 

We introduce a new method for detecting ultra-diffuse galaxies (UDGs) by searching for over-densities in intergalactic globular cluster (GCs) populations. Our method is based on an application of the log-Gaussian Cox process. This method is applied to the GCs data obtained from the PIPER survey, a Hubble Space Telescope imaging program targeting the Perseus cluster. We successfully detect all confirmed UDGs with known globular cluster populations in the survey. We also identify a potential galaxy that has no detected diffuse stellar content. Preliminary analysis shows that it is unlikely to be merely an accidental clump of globular clusters or other objects. If confirmed, this system would be the first of its kind. Simulations are used to assess how the physical parameters of the globular cluster systems within UDGs affect their detectability using our method. We quantify the correlation of the detection probability with the total number of GCs in the galaxy and the anti-correlation with increasing half-number radius of the GC system. The Sersic index of the GC distribution has little impact on detectability.