Speaker
Description
The magnitude gap (Δm₁₄), defined as the magnitude difference between the brightest cluster galaxy (BCG) and the fourth brightest galaxy in a cluster, is widely used to probe the formation history of dark matter halos and the dynamical age of galaxy clusters. For example, early-forming clusters are expected to exhibit large magnitude gaps due to galaxy merging.
In this work, we utilize the RASS–MCMF sample of X-ray-selected clusters in combination with imaging data from the Legacy Survey DR9/DR10 to identify member galaxies for 6,352 clusters. A data-driven statistical background subtraction is applied to assign probabilities of galaxies as cluster members, and a red-sequence (RS) model is used to further select passive cluster galaxies. BCGs are further identified through a combination of color, magnitude, and spatial filters.
Based on the galaxy memberships and BCG identification, we compute the magnitude gap for each cluster. These measurements will enable the probe to the formation of massive halos in statistical analyses.
| Participate the oral/poster presentation award competition | Yes |
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