Fleming

Resolving emission from the CGM directly in far-UV emission lines with SPRITE and other SmallSats

Direct detection of UV emission from the CGM of local galaxies is exceedingly difficult for current observatories, such as HST, as the combination of low surface brightness and the small solid angle of COS and STIS limit the ultimate sensitivity. SmallSats, on the other hand, could be the ideal platform for such observations, despite having much less collecting area. The SPRITE CubeSat is one such example of an upcoming mission capable of resolving emission from O VI, C IV, and other lines around z < 0.05 galaxies. SPRITE combines a high throughput, but small (18 x 16 cm), far-UV (100 - 175 nm) bandpass telescope with a low-resolution imaging spectrograph featuring a 10-arcsecond by 0.5 degree long-slit. This design results in a grasp (the product of effective area and solid angle subtended) roughly 18-times that of HST-COS, making SPRITE more efficient for sampling extended emission. With a low-background, photon-counting detector, SPRITE can resolve surface brightnesses commensurate with the expected values for local galaxy CGM emission lines in roughly 100ks on ~ 10 x 30" scales. SPRITE, set to launch in early 2025, is one of several in development or planned SmallSats capable of such observations. We present on the status and anticipated capabilities of SPRITE and a selection of other upcoming or planned missions, including a potential far-UV integral-field spectrograph, and the prospects for the first ever catalog of resolved maps of the CGM in local galaxies in UV emission lines.