Gas Phase Distribution in the Neutral ISM: A Comparison between Observation and Numerical Simulation
This study compares Hi 21-cm emission-absorption observations from the GWA and LAB surveys with TIGRESS numerical simulations to determine that the neutral interstellar medium consists of approximately 19.8% cold, 32.5% unstable, and 47.8% warm phases, a distribution that aligns with simulation results and highlights the need for future sensitive radio observations to further constrain these gas fractions.