Presentation #215.04 in the session “Galaxies and Environment”.
For over half a century, observational astrophysics has been eager to detect and map the most massive baryonic component of galaxies: warm-hot coronal gas extending into the circumgalactic medium (CGM). The warm-hot phase in galaxy halos accounts for more mass than the stars within the parent galaxy. Despite its importance to galaxy evolution, this phase of gas is entirely unmapped in the nearby universe. Morphological characteristics of the coronal gas phase, such as size, filling factor, and extent of filamentary or cloud-like structures, are impossible to determine through pencil-beam absorption line studies. The evolution of galaxies relies heavily on the properties of gaseous halos. Therefore, our understanding of this evolution requires us to map and measure these understudied regions. To this end, I present Aspera, a SmallSat mission to create the first maps of warm-hot coronal gas in nearby galaxies. With Aspera, we will constrain the amount of halo gas, its cooling rate, recycling timescale, and the physical extent of ionized outflows — properties crucial to our understanding of galaxies and their evolution — for the first time.