Slitless spectroscopy simulations of Milky Way dwarf satellite galaxies using TMT-WFOS

Abstract

Wide Field Optical Spectrograph (WFOS) is the first light instrument of Thirty Meter Telescope (TMT), which will be one of the wide field spectrographs for optical spectroscopy and can probe the faintest limits. In order to reach the faintest limits provided by the aperture of TMT, WFOS is designed to have a multi-object slit-based spectrograph instead of a fiber-based one. WFOS can observe about ∼60 objects in a given exposure and cover the entire wavelength range in low resolution (R∼1500) observing mode. Slitless spectroscopy has been popular in space-based instruments. However, it is not pursued in ground-based observatories due to the atmospheric effects. Considering the large plate scale of TMT and oversampling of the seeing disk, we can extract the individual spectra from WFOS slitless observing mode. Here, we try to understand the feasibility of the slitless mode of TMT-WFOS and the sensitivity limit for various field densities focusing on Milky Way satellite galaxies. We study the background contamination due to the bright targets and the density distribution of the satellite galaxy fields