Detectability test of H-2 Lyman-Werner band emission for a far-ultraviolet imaging spectrograph FIMS

Abstract

Molecular hydrogen (H-2) is excited by far-ultraviolet (far-UV) photons and emits fluorescent emission in the far-UV bands and in the near- and the mid-infrared bands. Observations of H-2 in these photodissociation regions (PDRs) are important in tracing star-forming molecular clouds and in understanding the interaction between newly born stars and molecular clouds. We use the typical PDR model of Sternberg to estimate the observing time (or integration time) required to detect PDRs with the Far-ultraviolet IMaging spectrograph (FIMS) onboard KAISTSAT-4, the first Korean scientific satellite. The observing time is calculated using a formula based on a rigorous hypothesis testing for the detection limit, in contract to the often-used signal-to-noise ratio. The estimated observing time is also compared with the expected exposure time from one-year all-sky survey.