Concept integral field unit spectrometer instrument for the next-generation mm-wave cosmological surveys

TL;DR

This work addresses the limitations of past mm-wave surveys—confusion and lack of redshift indicators—by proposing a 100-pixel mm-wave integral field unit spectrometer with $R\sim200$ that can operate on a 10‑m class telescope to perform volumetric, redshift-complete surveys down to $L_*$ across $z\sim1-12$. The approach leverages on-chip spectrometers and highly multiplexed KID detectors to fill the focal plane with ~25k detectors per instrument and capture the full 1.2 mm atmospheric window, enabling both resolved galaxy surveys and Line Intensity Mapping (LIM). Key contributions include a detailed concept for a scalable, open-source collaboration, an assessment of enabling technologies, and discussion of telescope- and band-specific variants, all aimed at delivering tens of thousands of galaxies with spectroscopic redshifts within a few years. The work anticipates significant impact on cosmic star-formation history studies by offering an unbiased mass-luminosity census and providing the infrastructure for collaborative, multi-institution instrument development. The proposed open-source model and modular design philosophy are positioned to accelerate deployment on existing facilities and pave the way for future multi-band LIM capabilities.

Abstract

Past millimeter-wave galaxy surveys have primarily probed the brightest starburst galaxies only and suffered heavily from confusion. The interpretation of existing surveys has also been hindered by the lack of reliable redshift indicators for measuring distances for entire samples. Thanks to recent advances in mm-wave detector technologies we can now overcome these limitations, and conduct the first truly volumetric surveys of star-forming galaxies at mm-wavelengths approaching the L* luminosities of typical galaxies, with ~1000 redshift slices spanning most of the Cosmic star-forming volume (z ~ 1--12) with nearly uniform mass and luminosity selection. We describe an instrument concept capable of delivering such surveys with the technologies available today, which can be built and operated on a ground-based mm-wave facility in the near future. Such integral field unit spectrometers can resolve and identify redshifts for up to to 25,000 star-forming galaxies per year even when operated on a 10-m class telescope. On a larger aperture it can do the same faster or probe even deeper. We propose a collaboration open-source initiative to design, build, and operate one or several such cameras through the shared contributions of leading experts and telescopes from around the globe.

Figures (1)

• Figure 1: Typical redshift selection curves for a star-forming galaxies with $L$$\sim$10$^{12}$ L$_{\odot}$ at various wavelengths. Left: continuum selection curvesKovacs2010. Right: Estimated combined CO-selection curves assuming thermalized CO transitions. As the high-$J$ CO transitions may be sub-thermally excited, the actual selection curves will likely fall somewhat below this prediction at high $z$. The 1.2 mm CO intensity confusion limit for an $R$$\sim$200 spectrometer on a 10-m class telescope is also shown, expected at around 3$\times$10$^{11}$ L$_\odot$, which corresponds $\sim$3 $L_*$ in the local Universe. However, this confusion limit is likely closer to, or below, $L_*$ for the distant Universe, given that global star-formation history peaked at $z$$\sim$2--3.