The SIRMOS mission concept: a space-based near-IR spectroscopic survey of 100 million galaxies in the Euclid Wide Survey footprint

SIRMOS is a concept for a NASA Astrophysics MIDEX mission designed to revolutionize our understanding of cosmic inflation, dark energy, and neutrino masses by mapping the large-scale structure of distant galaxies with unprecedented breadth and precision. Leveraging the expansive Euclid imaging covering ~14,000 sq deg, SIRMOS will obtain slit spectra for 100 million galaxies at redshifts from 1 to 4 using a powerful multi-object spectroscopy capability enabled by a 2K×1K Digital Micro-mirror Device (DMD) as described in Robert Content's accompanying paper on the optical design. SIRMOS uniquely exploits Euclid’s deep near-infrared catalog for efficient target selection, collecting high-precision spectra (R>1000) with continuous wavelength coverage from 1.25-2.5 microns to eliminate gaps in redshift measurements and minimizes systematic biases. By leveraging heritage bus and thermal designs, SIRMOS offers a cost-effective path to crucial cosmological measurements.