Illuminating the Physics of Cosmic Origin and Evolution: A UK Space Frontiers 2035 White Paper

TL;DR

This white paper advocates for a space-based spectroscopic survey mission, SIRMOS, to map high-redshift galaxies, aiming to address fundamental cosmological questions about the universe's origins, expansion, and neutrino masses.

Contribution

It proposes a novel space mission concept, SIRMOS, utilizing advanced instrumentation to conduct an unprecedented large-scale galaxy survey for cosmology.

Findings

Design of a high-throughput spectroscopic survey for 100 million galaxies

Application of advanced space instrumentation technologies in cosmology

Potential to resolve key questions about cosmic inflation and neutrino masses

Abstract

Understanding the Universe's origins and evolution remains one of the most fundamental challenges in modern cosmology. This white paper explores three key science priorities in this field: unravelling the physics of cosmic inflation, investigating the accelerating expansion of the Universe, and precisely measuring the sum of the neutrino masses. Achieving these goals requires a dedicated survey to map the large-scale structure at high redshift in unprecedented detail. We describe how this can be achieved through a mission concept called SIRMOS, providing a high-throughput, highly multiplexed spectroscopic capability to obtain accurate redshifts for over 100 million galaxies over a wide sky area. Such a survey would leverage the deepest existing wide-area photometric catalogues for targeting, with spectra offering continuous 1.25-2.5~$\mu$m wavelength coverage at moderate resolution, allowing precise redshift measurements in the $1<z<4$ range with minimal bias. We outline the scientific opportunities this presents. Recent years have seen significant advances in instrumentation, including digital micromirror devices, complex telescope mirrors, large detector arrays, and data processing pipelines. While these technologies have been demonstrated in terrestrial applications, such a survey is a unique opportunity to apply these proven capabilities in space to address fundamental questions in cosmology. Participation in such a mission will simultaneously deliver a compelling science case, help align UK Space Agency and STFC strategies, demonstrate the UK's growing capability in end-to-end space missions, and strengthen the national space economy through high-value industrial participation.