submillimetre galaxies

submillimetre galaxies
Name	Submillimetre galaxy
Epoch	J2000
Redshift	1–6
Type	Irregular
Mass	10^10–10^12 M☉
Names	SMG

submillimetre galaxies are a class of high-redshift, dust-enshrouded starburst galaxies detected primarily via their strong emission at submillimetre wavelengths. They are characterized by extreme infrared luminosities, rapid star formation rates, and frequent association with mergers and dense environments. Observations of these systems inform models of galaxy assembly, black hole growth, and the evolution of large-scale structure.

Overview

Submillimetre galaxies were recognized as distinct populations through coordinated efforts involving facilities such as the James Clerk Maxwell Telescope, Atacama Large Millimeter/submillimeter Array, Herschel Space Observatory, Spitzer Space Telescope, and targeting by instruments like the Submillimetre Common-User Bolometer Array and the SCUBA-2. They occupy redshifts broadly between z≈1 and z≈6 and exhibit luminosities comparable to quasars such as 3C 273 and ultraluminous infrared galaxies exemplified by Arp 220. SMGs are often studied alongside populations like Lyman-break galaxies, dusty star-forming galaxies, and ultraluminous infrared galaxies to place them within the broader context of galaxy evolution and the assembly history probed by surveys such as COSMOS (survey), GOODS (astronomy), and the Sloan Digital Sky Survey.

Discovery and Observational Techniques

The discovery epoch for these sources was propelled by instrumentation advances at observatories including the James Clerk Maxwell Telescope, the Institut de Radioastronomie Millimétrique facilities, and the Submillimeter Array; pioneering surveys with SCUBA on the JCMT revealed bright sources that lacked obvious optical counterparts in fields surveyed by Hubble Space Telescope and Keck Observatory. Follow-up spectroscopy using telescopes like the Very Large Telescope, Gemini Observatory, and the Karl G. Jansky Very Large Array provided redshifts and molecular-line detections (e.g., CO) that tied these objects to massive reservoirs traced also by instruments at the National Radio Astronomy Observatory. Techniques include continuum mapping, interferometric imaging with ALMA, spectral-line scans for CO and [C II] with NOEMA (NOrthern Extended Millimeter Array), and gravitational lensing studies exploiting foreground clusters catalogued by Planck (spacecraft) and surveys such as South Pole Telescope.

Physical Properties and Energy Sources

Measured properties derive from multiwavelength campaigns combining data from Chandra X-ray Observatory, XMM-Newton, and mid-infrared data from Spitzer Space Telescope to assess contributions from active galactic nuclei hosted by supermassive black holes seen in systems like Mrk 231. Molecular gas masses estimated via CO and dust continuum imply baryonic masses comparable to systems such as M82 and NGC 6240, while star formation rates often exceed rates seen in Milky Way and approach those inferred for luminous quasars in the Sloan Digital Sky Survey. Energy sources include starburst-driven heating and obscured accretion onto black holes associated with objects catalogued by the Two Micron All Sky Survey and identified in X-ray surveys by Chandra; disentangling these contributions uses mid-IR diagnostics developed with data from Infrared Astronomical Satellite and line ratios measured with instruments on Herschel Space Observatory.

Formation, Evolution, and Environments

Theoretical models tested against observations employ cosmological simulations from projects such as Illustris, EAGLE (project), and zoom-in calculations by groups affiliated with institutions like the Max Planck Institute for Astrophysics and Harvard–Smithsonian Center for Astrophysics; these models tie rapid star formation episodes to major mergers similar to interactions inferred in systems observed with the Subaru Telescope and to gas-rich accretion predicted in the cold-flow paradigm developed by teams at Princeton University and University of California, Berkeley. SMGs are often located in overdense regions linked to proto-clusters discovered in surveys by Vera C. Rubin Observatory preparatory work and by wide-field projects such as UKIDSS and the VLA-COSMOS survey, suggesting evolutionary pathways that lead to massive quiescent galaxies and brightest cluster galaxies catalogued in cluster studies like those from the ROSAT All-Sky Survey.

Role in Cosmic Star Formation and Cosmology

SMGs contribute a substantial fraction of the cosmic infrared background measured by missions including COBE and Planck (spacecraft), and they are significant contributors to the cosmic star formation rate density at z≈2–3 established by compilation efforts involving data from GALEX, WISE, and ground-based near-IR spectrographs on Keck Observatory. Their clustering amplitudes and halo mass estimates derived from cross-correlation studies using data sets from SDSS and CFHTLS inform halo occupation models developed in the context of the Lambda-CDM paradigm and influence constraints on baryon cycling, feedback prescriptions, and the role of obscured growth in shaping relations like the M–sigma relation between black hole mass and host properties.

Notable Surveys and Key Examples

Key surveys include early deep maps by SCUBA on the James Clerk Maxwell Telescope, wide-area programs with Herschel Space Observatory such as HerMES, follow-up ALMA programs led by teams at National Radio Astronomy Observatory and European Southern Observatory, and catalogues from the South Pole Telescope and Atacama Cosmology Telescope. Well-studied individual sources and analogues used as benchmarks include luminous examples discovered in fields observed by Hubble Space Telescope and spectroscopically confirmed with Keck Observatory and VLT, while gravitationally lensed cases identified in surveys by Planck (spacecraft) and Herschel provided high-fidelity structural and kinematic information exploited by research groups at California Institute of Technology and University of Cambridge.

Category:Galaxy types