The Origin and Distribution of Diffuse Hot Gas in the Spiral Galaxy NGC 3184

Deep Chandra exposures reveal the presence of diffuse X-ray emission with a luminosity of 1.3 × 10³⁹ ergs s^-1 from the spiral galaxy NGC 3184. This appears to be truly diffuse thermal emission distinct from the low-luminosity emission from low-mass X-ray binaries (LMXBs). While the unresolved emission from older LMXBs is more uniformly distributed across the galaxy, the diffuse X-ray emission is concentrated in areas of younger stellar populations and star-forming regions. The surface brightness of the diffuse emission over the spiral arms is 5 times greater than in off-arm regions, and 8 times brighter in H II regions than in non–H II regions. Spectral fits to the diffuse thermal emission are consistent with a low-temperature component, T ∼ 1.5 × 10⁶ K, plus a higher temperature component, T ∼ 5 × 10⁶ K.