The Korea Large Spectroscopic Telescope (KLST) project for flux-limited spectroscopic survey in the southern hemisphere

Abstract

The Korea Large Spectroscopic Telescope (KLST) is proposed as a next-generation facility with a current baseline design utilizing twin 6.5m telescopes (effective 9.2m) in the Southern Hemisphere. Departing from the color-selected targeting strategies of current-generation surveys, KLST aims to conduct a flux-limited Hubble Depth Survey (HDS), targeting all sources brighter than r ≈ 22 to secure an unprecedented, unbiased sample of over 70 million galaxies up to z ≈ 1.4. This proceeding outlines the primary science drivers of KLST: precision cosmology (constraining dark energy, measuring the matter-radiation equality scale, and probing the origin of Inflation via primordial non-Gaussianity), galaxy evolution in extreme environments (merging clusters and intracluster light), and deep Galactic archaeology (tracing the merger history of the Milky Way and the Magellanic Clouds). Furthermore, we highlight the strategic synergies between KLST and other major facilities — acting as a high-resolution spectroscopic anchor for SPHEREx and providing comprehensive follow-up for LSST. Supported by a high-density focal plane with 13,000 robotic fiber positioners and dual-resolution (R ∼6,000/45,000) spectrographs, KLST aims to establish a new paradigm in observational astrophysics.