Two-degree Field Galaxy Redshift Survey

Two-degree Field Galaxy Redshift Survey is a major redshift survey of galaxies conducted with the Anglo-Australian Telescope using the Two-degree Field (2dF) multi-fiber spectrograph. The project mapped redshifts for over 220,000 galaxies to measure large-scale structure and cosmological parameters, involving collaborations among institutions such as the Australian Astronomical Observatory, University of Cambridge, University of Oxford, University of Melbourne, and the Sloan Digital Sky Survey teams. The survey overlapped and contrasted with contemporaneous efforts like the Las Campanas Redshift Survey, CfA Redshift Survey, and 2MASS Redshift Survey, providing measurements that informed analyses by groups including the Max Planck Institute for Astrophysics, Lawrence Berkeley National Laboratory, and the Institute of Astronomy, Cambridge.

Introduction

The survey was conceived to map galaxy clustering across contiguous regions centered on the Southern Galactic Pole and selected northern fields, extending earlier work by the First Redshift Survey teams and echoing methodologies developed at the Palomar Observatory and Kitt Peak National Observatory. It targeted magnitude-limited samples drawn from the Automatic Plate Measuring Facility scans of the UK Schmidt Telescope photographic plates and coordinated with datasets from the Two Micron All Sky Survey and the COSMOS catalogue. Led by astronomers including Matthew Colless, John A. Peacock, and Geraint F. Lewis, the collaboration included researchers from institutions such as University of Sydney, Australian National University, University of Edinburgh, University of Durham, and Harvard-Smithsonian Center for Astrophysics.

Survey Design and Instrumentation

Survey design centered on the Two-degree Field instrument, a robotic fiber positioner developed at the Anglo-Australian Observatory in partnership with engineering teams from the University of Oxford and the Royal Greenwich Observatory. The 2dF spectrograph could deploy 400 optical fibers across a two-degree field of view, enabling simultaneous spectroscopy of hundreds of targets—an advance following earlier multiplexing efforts at the William Herschel Telescope and the European Southern Observatory. Target selection relied on photometry from the UK Schmidt Telescope and plate scans processed by the Automatic Plate Measuring Facility, with calibration tied to standard stars observed by teams from the Royal Observatory, Edinburgh. The instrumentation design incorporated gratings and detectors similar to those used at the Anglo-Australian Observatory's other facilities and built on expertise from groups at the Mount Stromlo Observatory and the CSIRO.

Data Collection and Processing

Observations ran from the late 1990s into the early 2000s and were coordinated with scheduling from the Anglo-Australian Telescope operations team and project scientists at the Australian Astronomical Observatory. Raw spectra were reduced via pipelines built by software groups at the University of Durham and the Institute of Astronomy, Cambridge, incorporating algorithms influenced by work at the European Southern Observatory and analysis techniques used by the Sloan Digital Sky Survey consortium. Redshift determination employed cross-correlation methods developed by researchers at the University of Cambridge and signal extraction routines refined at the National Optical Astronomy Observatory. The survey's catalogues were assembled, curated, and released to the community with data management support from the Centre for Astrophysics and Supercomputing at the Swinburne University of Technology and mirrored at archives including the NASA/IPAC Extragalactic Database and the Centre de Données astronomiques de Strasbourg.

Scientific Results and Discoveries

The survey produced precise measurements of the galaxy two-point correlation function and the power spectrum of density fluctuations, enabling cosmological parameter estimation by teams at the Max Planck Institute for Astrophysics, Institute of Cosmology and Gravitation, and the California Institute of Technology. Results constrained the matter density parameter and the bias between galaxies and dark matter, complementing cosmic microwave background analyses from the Wilkinson Microwave Anisotropy Probe and later the Planck (spacecraft). The 2dFGRS data revealed features related to baryon acoustic oscillations investigated by researchers at the University of Portsmouth and the University of St Andrews, and informed studies of redshift-space distortions and galaxy peculiar velocities by groups at the University of Edinburgh and Imperial College London. The survey enabled galaxy population studies—luminosity functions, spectral classification, and environmental dependencies—conducted by scientists from the Australian National University, Monash University, and the University of Queensland. Collaborators compared 2dFGRS findings with results from the DEEP2 Redshift Survey, VIMOS-VLT Deep Survey, and IRAS Point Source Catalog redshift survey to test theories developed at the Perimeter Institute for Theoretical Physics and by researchers affiliated with Princeton University.

Legacy and Impact on Cosmology

The 2dFGRS legacy includes foundational datasets used in ongoing analyses by institutions such as the Max Planck Institute for Astronomy, University of Cambridge, University of Oxford, and the Australian National University. Its measurements informed photometric redshift calibration efforts at the Lick Observatory and shaped survey strategies for successors like the Sloan Digital Sky Survey, the Dark Energy Survey, the WiggleZ Dark Energy Survey, and plans for the Wide Field Infrared Survey Telescope and the Euclid (spacecraft). The methodological innovations in multi-fiber spectroscopy and pipeline reduction influenced instrumentation at the European Southern Observatory and detector developments at the National Astronomical Observatory of Japan. The survey's catalogues continue to be incorporated into meta-analyses by the International Astronomical Union working groups and data archives maintained by the Centre de Données astronomiques de Strasbourg and the NASA/IPAC Extragalactic Database, while its scientific outcomes remain cited in theoretical work from the Institute for Advanced Study and applied studies at the Lawrence Berkeley National Laboratory.

Category:Galaxy surveys Category:Cosmology