The Scientific Impact of a Noiseless Energy-Resolving Detector for a Future Exoplanet-Imaging Mission

Future space missions that aim to detect and characterize Earth-like exoplanets will require an instrument that efficiently measures spectra of these planets, placing strict requirements on detector performance. The upcoming Roman Space Telescope will demonstrate the performance of an electron-multiplying charge-coupled device (EMCCD) as part of the coronagraphic instrument (CGI). The recent LUVOIR and HabEx studies baselined pairing such a detector with an integral field spectrograph (IFS) to take spectra of multiple exoplanets and debris disks simultaneously. We investigate the scientific impact of a noiseless energy-resolving detector for the planned Habitable Worlds Observatory's (HWO) coronagraphic instrument. By assuming higher quantum efficiency, higher optical throughput, and zero noise, we effectively place upper limits on the impact of advancing detector technologies. We find that energy-resolving detectors would potentially take spectra of hundreds of additional exoplanets "for free" over the course of an HWO survey, greatly increasing its scientific yield.