Investigating the Galactic-scale Behavior of Hot Diffuse Plasma in M51 with Deep Chandra Observations

Diffuse hot ionized gas is theorized to play a pivotal role in governing the evolution of massive star-forming spiral galaxies, however the underlying physical processes remain largely uncertain. We perform high-resolution spatial and spectral analyses of the hot diffuse plasma in the grand design spiral galaxy M51, leveraging deep Chandra X-ray data complemented by multi-wavelength observations. Our analysis demonstrates the soft diffuse X-ray emission closely traces far-ultraviolet (FUV) emission in the galactic disk, displaying a square-root intensity dependence on the star formation activity, as traced by FUV emission - consistent with previous findings for other two nearby spirals (M101 and M83). Additionally, we find the X-ray plasma temperature and intensity vary systematically with spiral arm phase after accounting for X-ray absorption effects in the disk. The plasma displays a log-normal temperature distribution which peaks within the prominent spiral arms. We further characterize the large-scale spatial intensity and temperature distribution of the volume-filling hot plasma across M51. These new observational insights provide key constraints on the origin and evolution of the hot plasma in this archetypal spiral, and how stellar feedback processes regulate the cycling of gas through the interstellar and circumgalactic media.