starburst galaxies

starburst galaxies
Name	Starburst galaxy
Type	Galaxy classification
Epoch	Cosmic
Redshift	Variable
Mass	Variable
Size	Variable
Notable	M82, NGC 253, Arp 220

starburst galaxies are galaxies undergoing a transient episode of exceptionally high star formation, producing stars at rates far exceeding those of typical galaxies such as Milky Way or Andromeda. These systems appear in diverse environments including Orion Nebula-hosting regions, interacting pairs like Antennae Galaxies and merging systems exemplified by Arp 220, and are prominent in deep surveys such as Hubble Deep Field and Sloan Digital Sky Survey. Observational programs using facilities like Hubble Space Telescope, Spitzer Space Telescope, Very Large Array, Atacama Large Millimeter Array, and Chandra X-ray Observatory have characterized their multiwavelength signatures and environmental connections.

Definition and Characteristics

A starburst episode is defined by a star formation rate that would consume the available cold gas reservoir on a timescale much shorter than the galaxy's age, often <100 Myr, a criterion applied in surveys like Sloan Digital Sky Survey and COSMOS survey. Typical observational characteristics include high infrared luminosity classified in schemes such as IRAS-defined luminous and ultraluminous infrared galaxy catalogs (e.g., ULIRG lists), strong emission-line spectra cataloged in Sloan Digital Sky Survey pipelines, compact nuclear star clusters resembling objects found in M82 and NGC 253, and elevated supernova rates comparable to historical events like SN 1987A in active regions. Many are identified by excess far-infrared output measured by missions such as IRAS, Herschel Space Observatory, and Spitzer Space Telescope.

Causes and Triggers

Major mergers between galaxies, exemplified by systems in the Toomre sequence and studies of Antennae Galaxies, are primary triggers, funnelling gas into central regions through tidal torques described in models by researchers associated with institutions like Max Planck Institute for Astrophysics and Princeton University. Minor mergers and tidal interactions seen in groups such as Local Group and clusters like Virgo Cluster can also induce bursts via bars and gas inflows traced to structures like the Barred spiral morphology. External processes including ram pressure stripping in environments like Coma Cluster or cold accretion from cosmic filaments studied in cosmological simulations at Lawrence Berkeley National Laboratory and Caltech can enhance central gas density. Secular processes driven by instabilities in disks, studied by teams at Carnegie Institution for Science and University of Cambridge, form rings and bars that concentrate gas and trigger circumnuclear starbursts.

Star Formation Processes and Rates

Star formation in these systems proceeds in dense molecular complexes where giant molecular clouds similar to regions in Orion Nebula collapse under self-gravity, often aided by shocks from tidal interactions modeled in codes developed at Harvard–Smithsonian Center for Astrophysics and MIT. Measured rates span from a few to >1000 solar masses per year in extreme cases like Arp 220, derived from tracers including hydrogen recombination lines used by teams at European Southern Observatory and molecular line emission (e.g., CO, HCN) observed with Atacama Large Millimeter Array and Nobeyama Radio Observatory. Feedback from massive stars and core-collapse supernovae seen in remnants such as Cassiopeia A regulates efficiency, while the initial mass function debate engages groups at Max Planck Institute for Astronomy and Institute for Advanced Study.

Morphology and Examples

Morphologies range from compact nuclear starbursts in systems like M82 and NGC 253 to extended disk-wide bursts in objects discovered in the Hubble Ultra Deep Field. Classic examples cataloged in the Arp Atlas of Peculiar Galaxies include Arp 220 and the Antennae Galaxies, while nearby prototypes include M82, NGC 253, and NGC 3310. Many are cataloged in surveys by Two Micron All Sky Survey and Sloan Digital Sky Survey, and prominent interacting systems studied by teams at California Institute of Technology and University of California, Berkeley illustrate tidal tails, bridges, and rings produced in encounters modeled by Toomre and Toomre-style simulations.

Spectral Properties and Observational Signatures

Starburst systems show strong far-infrared continua measured by IRAS and Herschel Space Observatory, polycyclic aromatic hydrocarbon features targeted by Spitzer Space Telescope, and prominent optical emission-line ratios cataloged in Sloan Digital Sky Survey that place them on diagnostic diagrams used by researchers at Johns Hopkins University and University of Oxford. High-energy signatures include soft X-ray emission from hot winds observed with Chandra X-ray Observatory and hard X-rays where obscured active nuclei are present as studied by XMM-Newton. Molecular transitions (CO, HCN) traced by Atacama Large Millimeter Array and Plateau de Bure Interferometer reveal dense gas fractions, while radio continuum measured by Very Large Array probes nonthermal synchrotron from supernovae similar to observations of SN 1987A.

Evolution and Life Cycle

Starburst episodes are typically short-lived relative to galactic lifetimes, with durations constrained by gas depletion, feedback-driven outflows observed in M82 and Arp 220, and quenching processes studied in cluster environments like Virgo Cluster. Post-starburst remnants identified in surveys such as Sloan Digital Sky Survey and follow-up by groups at University of Hawaii often show Balmer-strong spectra and morphological settling into systems resembling elliptical galaxies in scenarios proposed by researchers at Princeton University and Max Planck Institute for Astrophysics. Repeated bursts may occur during hierarchical assembly traced through simulations from Millennium Simulation and observatories like Keck Observatory.

Role in Galaxy Evolution and Cosmology

Starburst galaxies contribute disproportionately to cosmic star formation history measured in deep fields like Hubble Deep Field and missions including Spitzer Space Telescope and Herschel Space Observatory, influencing reionization-era studies linked to programs at European Southern Observatory and Space Telescope Science Institute. Their feedback in the form of winds and metal enrichment affects intergalactic medium properties studied by teams at Carnegie Institution for Science and Lawrence Livermore National Laboratory, while luminous infrared populations such as ULIRG samples inform models of stellar mass assembly used by researchers at California Institute of Technology and University of Cambridge. Observational campaigns with facilities including James Webb Space Telescope, Atacama Large Millimeter Array, and Thirty Meter Telescope aim to connect local prototypes like M82 with high-redshift analogs discovered in surveys like COSMOS survey and Great Observatories Origins Deep Survey.

Category:Galaxies