Astronomy Special Seminar

Ultraviolet (UV) spectroscopy provides powerful diagnostics of the multiphase gas that regulates galaxy evolution, yet diffuse emission from the warm-hot (10⁵–10⁶K) circumgalactic medium (CGM) has remained largely unexplored. This talk will present Aspera, a NASA Astrophysics Pioneers SmallSat mission led by PI Dr. Carlos Vargas, designed to map faint O VI (103.2 nm) emission tracing warm-hot gas in the CGM of nearby galaxies. By directly imaging this component, Aspera will make pioneering spatially resolved measurements of the composition, morphology, and kinematics of the CGM, providing new window into galactic feedback and accretion processes. I will provide an overview of Aspera's science and discuss the ongoing instrument optical alignment and calibration activities. As Aspera progresses through final calibration and environmental testing ahead of its planned 2026 launch, I will also discuss Aspera's extended mission program to map O VI emission at the interface of Large Magellanic Cloud (LMC) CGM with the Milky Way CGM to reveal the kinematics and morphology of warm-hot CGM gas in a galaxy merger.

The second part of the talk will focus on UV detector technology development, highlighting our effort to characterize the quantum efficiency and noise performance of silicon-based detectors using an EMCCD test bed developed in collaboration between UArizona and JPL/MDL. This work aims to advance photon-counting architectures and detector optimization for next-generation UV spectroscopy and imaging missions.