Thermodynamic maps of HCG15 produced from XMM-Newton. From left to right, the panels show the X-ray surface brightness, X-ray temperature, and pseudo-entropy. Contours show the X-ray surface brightness as per the left panel, starting at a level of 1.2 × 10⁻⁶ counts s⁻¹ (4σ) and scaling by a factor of $\sqrt{2}$. The ‘X’ markers in circles denote the positions of the six group-member galaxies. The ‘+’ indicates the SZ position of the background cluster at z ≃ 0.88 reported by Klein et al. (2024), with the circle denoting a 500 kpc radius at redshift 0.88.