Submillimetre astronomy

Submillimetre astronomy
Name	Submillimetre astronomy
Wavelength	0.3–1 mm
First observed	1960s
Major instruments	James Clerk Maxwell Telescope, Atacama Large Millimeter/submillimeter Array, Herschel Space Observatory
Notable persons	William Herschel, Martin Ryle, John Townes

Contents

Submillimetre astronomy is the astronomical study of celestial emission at wavelengths roughly between 0.3 and 1 millimeter, bridging the far-infrared and millimetre regimes. The field developed through collaborations among observatories such as the James Clerk Maxwell Telescope, space missions like the Herschel Space Observatory, and interferometers including the Atacama Large Millimeter/submillimeter Array, producing key results on cold dust, molecular gas, and star formation. Techniques and facilities derive from precursor work at institutions such as the Royal Observatory, Edinburgh, the California Institute of Technology, and the Max Planck Institute for Radio Astronomy.

Overview

Submillimetre astronomy probes cold astrophysical processes in regions studied by the Infrared Space Observatory, the Spitzer Space Telescope, and the Planck mission, revealing emission from dust, molecules, and fine-structure lines. Observations complement results from the Hubble Space Telescope, the Chandra X-ray Observatory, and the Very Large Array by tracing reservoirs of baryons in galaxies examined by the Sloan Digital Sky Survey and the Two Micron All Sky Survey. Historical milestones include work at the Kitt Peak National Observatory, experiments led by researchers at the Harvard–Smithsonian Center for Astrophysics, and development at the Jet Propulsion Laboratory.

Key single-dish telescopes include the James Clerk Maxwell Telescope on Mauna Kea and the Caltech Submillimeter Observatory (historical) at Mauna Kea, while major interferometers include the Atacama Large Millimeter/submillimeter Array in the Atacama Desert and the Submillimeter Array on Mauna Kea. Spaceborne platforms that advanced the field include the Herschel Space Observatory and the Planck satellite; balloon-borne projects such as BOOMERanG and BLAST provided complementary data. Instrumentation developments at organizations like the European Southern Observatory, the National Radio Astronomy Observatory, and the Space Telescope Science Institute enabled superconducting detectors from laboratories at SRON Netherlands Institute for Space Research and the National Institute of Standards and Technology.

Observing in the submillimetre requires cryogenic detectors such as transition-edge sensors and kinetic inductance detectors developed at the Massachusetts Institute of Technology, the Rutherford Appleton Laboratory, and the University of Cambridge. Techniques include continuum mapping, spectral line surveys, and interferometric synthesis used by arrays like ALMA and the Very Large Array upgrade, relying on calibration strategies applied by teams at the European Space Agency and the National Aeronautics and Space Administration. Challenges include atmospheric opacity studied at Mauna Kea, the Atacama Desert, and the South Pole, calibration issues addressed at the Royal Observatory, Edinburgh, and precise pointing and phase stability pursued by engineers at the National Radio Astronomy Observatory and the California Institute of Technology.

Submillimetre observations uncovered cold cores in star-forming regions mapped in projects involving the Herschel Space Observatory, surveys coordinated with the Sloan Digital Sky Survey, and targeted campaigns by the James Clerk Maxwell Telescope. Discoveries include dense molecular clouds characterized with spectroscopy from the Atacama Large Millimeter/submillimeter Array, the detection of protoplanetary disks imaged in concert with the Hubble Space Telescope and the Very Large Telescope, and measurements of the cosmic infrared background linked to studies by the Spitzer Space Telescope and the Planck mission. Extragalactic science includes submillimetre galaxies investigated by teams at the Max Planck Institute for Astronomy and the Imperial College London, while astrochemistry results trace complex molecules using facilities at the Leiden Observatory and the Harvard–Smithsonian Center for Astrophysics.

Data reduction pipelines developed for instruments at the European Southern Observatory, NRAO, and the Joint ALMA Observatory employ algorithms originating from research groups at the University of Oxford, the University of Toronto, and the Max Planck Institute for Radio Astronomy. Calibration uses standards established by the International Astronomical Union and reference observations tied to sources monitored by the Royal Observatory, Edinburgh and the Caltech Submillimeter Observatory (historical). Techniques such as continuum subtraction, deconvolution, and mosaicking are implemented in software frameworks maintained by the Space Telescope Science Institute and the Centre National de la Recherche Scientifique.

Optimal sites include the Atacama Desert plateau hosting ALMA, the high-altitude summits of Mauna Kea, and the Amundsen–Scott South Pole Station where dry air minimizes water vapor absorption studied by teams from the National Science Foundation and the National Oceanic and Atmospheric Administration. Site testing programs led by the European Southern Observatory and the California Institute of Technology use radiometers and atmospheric models from the Jet Propulsion Laboratory and the University of Arizona to quantify precipitable water vapor and sky stability, guiding deployment decisions by institutions such as the National Radio Astronomy Observatory.

Planned facilities and missions include next-generation arrays proposed by the National Science Foundation, space concepts advanced at the European Space Agency and the National Aeronautics and Space Administration, and technology roadmaps coordinated by the International Astronomical Union and the Committee on Space Research. Projects under study involve larger aperture single dishes at sites championed by the Atacama Large Millimeter/submillimeter Array community, balloon experiments with teams from the California Institute of Technology and the University of Chicago, and far-infrared space telescopes envisioned by consortia including the Max Planck Society and the Jet Propulsion Laboratory.