SIRMOS optical design and science: NIR spectroscopy of 100,000,000 galaxies at 1 < z < 4 and R~1300

SIRMOS (Satellite for Infrared Multi-Object Spectroscopy) is a NASA MIDEX mission concept to map the universe in 3D over ~500 cubic gigaparsecs using 100-million [OIII] and H-alpha emission line galaxies at 1< z<4. SIRMOS will probe the cosmic origin by placing constraints on primordial non-Gaussianity, precisely measure the sum of neutrino masses, and differentiate dark energy and modification of general relativity as the cause for the observed low-redshift cosmic acceleration. SIRMOS has a 60 cm aperture telescope with 0.9 square-degree field, and 2.2-million micromirrors on a digital micro-mirror devices (DMD) to provide a programmable reflective slit mask for spectroscopy at R~1300 over 1.25-2.5 microns. The multiplex advantage is 4000 even if the DMD is only 2048 micromirrors long. An alternate design uses a prism instead of a grating. Another uses a microshutter array instead of a DMD. The SIRMOS mission design is presented in a companion paper by Gregory Wirth.