The SIRMOS mission concept: a space-based near-IR spectroscopic survey of 100 million galaxies in the Euclid Wide Survey footprint
SIRMOS is a mission concept for a future NASA Astrophysics Explorer opportunity that aims to revolutionize our understanding of the universe by mapping the large-scale structure of galaxies in unprecedented breadth and detail to explore cosmic origins and evolution. Specifically, the primary science goals of SIRMOS are to discover how cosmic inflation seeded large-scale structure, reveal the nature of the accelerating expansion of the universe, and measure the sum of neutrino masses to exceptionally high precision. Its secondary science goals include determining how environment shapes galaxy evolution at cosmic noon and beyond, and probing the Milky Way's dust-enshrouded regions, reaching the far side of our Galaxy. To accomplish its transformative science goals, SIRMOS executes a 3-year cosmology survey over the Euclid footprint of ~14,000 deg$^2$, obtaining slit spectra for ~100 million galaxies at 1<z<4. SIRMOS is the first space mission designed specifically to leverage Euclid's wide near-infrared (IR) imaging survey for target selection and employs a digital micro-mirror device (DMD) to acquire up to 4,000 simultaneous spectra over a wide 0.9 deg$^2$ field of view. The instrument's excellent spectral resolution of $R=1300$ and continuous wavelength coverage from 1.25--2.5 $μ$m capture the redshifts of distant galaxies with no gaps, reducing systematic biases to achieve ground-breaking science.