We examine the dependence of the ellipticity of globular clusters in the Milky way on their X-ray luminosity using two modern catalogs and combine them with optical and X-ray data from the literature. Kolmogorov–Smirnov tests applied across multiple subsets reveal statistically significant differences in the ellipticity distributions when both L_X and optical luminosity are considered. Two X-ray luminosity thresholds, L^∗ _X(M_V = −7) = 10^33.05 erg s⁻¹ and L^∗ _X(M_V = −7) = 10^32.01 erg s⁻¹, yield the most reliable distinction. In contrast to earlier findings based solely on optical data, our results demonstrate that globular clusters with the highest X-ray luminosity tend to have higher ellipticity on average.

Keywords: Ellipticity, Globular clusters, Milky Way, X-ray luminosity