Halving Luminosity–Mass Scatter in X-ray Clusters with an Aperture Correction Protocol

We present an empirical relation between cluster core radius and X-ray luminosity that reduces L_X–M scatter from 45.3% to 16.6%. Using 511 Planck–MCXC clusters, we quantify r_c/r_500 ∝ L_X-0.387 and demonstrate that fixed-profile aperture corrections systematically bias luminosities when this geometric diversity is present. This repository contains:- paper.pdf – Preprint submitted to MNRAS Letters- code.zip – Complete analysis pipeline (Python), including catalogs and results The code reproduces all figures and statistics in the paper.