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A wide-field, multi-line survey of CO in the Magellanic Clouds at parsec-scale resolution: characterising the molecular gas content with a 50-m single-dish submillimeter telescope

Francisca Kemper, Rosie Chen, Axel Weiss, Caroline Bot, Frédéric Galliano, Suzanne Madden, Oscar Morata, Naslim Neelamkodan, Rebeca Pirvu, Monica Rubio, Kazuki Tokuda

TL;DR

This paper advocates a large-aperture, wide-field CO survey of the Magellanic Clouds at parsec-scale resolution to build a comprehensive molecular atlas across varying metallicities. By combining CO and isotopologues with [CI], and integrating with existing HI/HII and dust data, the project aims to calibrate the CO-to-H$_2$ conversion factor and study ISM phases, kinematics, and feedback across environmental gradients. It argues that current facilities cannot provide the required combination of field of view, sensitivity, and resolution, and that a ~50 m single-dish telescope (the AtLAST concept) is needed to map the full molecular reservoir with total-power fidelity. The anticipated outcome is robust X$_{ m CO}$ calibrations, insights into molecular gas lifecycles, and benchmarks for high-redshift galaxy studies and cosmological simulations, enabling transformative progress in galaxy evolution research.

Abstract

The Large and Small Magellanic Clouds (LMC, SMC) are nearby dwarf galaxies whose proximity uniquely enables molecular cloud-scale resolution observations across the entire Magellanic system, a capability unmatched in any other external galaxy. Their low metallicities resemble conditions near the peak of cosmic star formation, allowing resolved studies of interstellar medium (ISM) phases, molecular cloud lifecycles, and feedback processes that regulate galaxy evolution. Comprehensive, wide-field spectroscopic mapping of CO and its isotopologues in different transitions, complemented by [CI] observations, and combined with already existing HI and HII surveys, will calibrate star-formation laws and gas-phase partition under low-metallicity conditions and furnish benchmarks for interpreting high-redshift galaxies and cosmological simulations. This science requires a large-aperture, wide-field submillimeter single dish with multi-pixel spectroscopic capabilities, operated from a high, dry site such as Chajnantor, to deliver fast, sensitive, high-resolution, degree-scale mapping with total-power fidelity. We present the case for a full molecular atlas of the Magellanic system, the enabling facility requirements, and the transformative impact on galaxy evolution studies

A wide-field, multi-line survey of CO in the Magellanic Clouds at parsec-scale resolution: characterising the molecular gas content with a 50-m single-dish submillimeter telescope

TL;DR

This paper advocates a large-aperture, wide-field CO survey of the Magellanic Clouds at parsec-scale resolution to build a comprehensive molecular atlas across varying metallicities. By combining CO and isotopologues with [CI], and integrating with existing HI/HII and dust data, the project aims to calibrate the CO-to-H conversion factor and study ISM phases, kinematics, and feedback across environmental gradients. It argues that current facilities cannot provide the required combination of field of view, sensitivity, and resolution, and that a ~50 m single-dish telescope (the AtLAST concept) is needed to map the full molecular reservoir with total-power fidelity. The anticipated outcome is robust X calibrations, insights into molecular gas lifecycles, and benchmarks for high-redshift galaxy studies and cosmological simulations, enabling transformative progress in galaxy evolution research.

Abstract

The Large and Small Magellanic Clouds (LMC, SMC) are nearby dwarf galaxies whose proximity uniquely enables molecular cloud-scale resolution observations across the entire Magellanic system, a capability unmatched in any other external galaxy. Their low metallicities resemble conditions near the peak of cosmic star formation, allowing resolved studies of interstellar medium (ISM) phases, molecular cloud lifecycles, and feedback processes that regulate galaxy evolution. Comprehensive, wide-field spectroscopic mapping of CO and its isotopologues in different transitions, complemented by [CI] observations, and combined with already existing HI and HII surveys, will calibrate star-formation laws and gas-phase partition under low-metallicity conditions and furnish benchmarks for interpreting high-redshift galaxies and cosmological simulations. This science requires a large-aperture, wide-field submillimeter single dish with multi-pixel spectroscopic capabilities, operated from a high, dry site such as Chajnantor, to deliver fast, sensitive, high-resolution, degree-scale mapping with total-power fidelity. We present the case for a full molecular atlas of the Magellanic system, the enabling facility requirements, and the transformative impact on galaxy evolution studies

Paper Structure

This paper contains 8 sections, 1 figure.

Table of Contents

  1. Abstract
  2. Scientific context and motivation
  3. The resolution--extent trade-off
  4. Inventory of phases of the ISM
  5. Chemistry, isotopologues, and CO-dark H$_2$
  6. Kinematics, turbulence, and feedback
  7. Current Status and Gaps
  8. What facility would be needed?

Figures (1)

  • Figure 1: CO(3--2) line intensity map of the Large Magellanic Cloud obtained at 5 to 6 pc resolution with APEX, overlayed on the H$\alpha$ MCELS map Grishunin_24_ObservingSmith1998. The white outline represents the surveyed area, and the green contours the detections of CO(3--2).