Cosmicflows

Cosmicflows
Name	Cosmicflows
Caption	Peculiar velocity field mapping from distance catalogues
Alt	Cosmicflows survey visualization
Start	2000s
Type	Astronomical survey
Discipline	Astronomy

Cosmicflows Cosmicflows is a series of observational projects and compiled catalogues mapping galaxy distances and peculiar velocities to study the large-scale structure of the Universe. The programs integrate distance indicators, redshift surveys, and flow-model reconstructions to address problems in observational cosmology, structure formation, and dark matter distribution. The efforts draw on collaborations among observatories, universities, and survey teams to produce public catalogues used by researchers studying cosmic expansion, gravitational flows, and anisotropies.

Overview

The project synthesizes distance measurements from multiple techniques to produce comprehensive compilations that probe cosmic flows, peculiar motions, and departures from uniform Hubble expansion. Major participants include teams associated with NASA, European Space Agency, Carnegie Institution for Science, Institut d'Astrophysique de Paris, Max Planck Society, California Institute of Technology, and observatories such as Palomar Observatory, Kitt Peak National Observatory, Arecibo Observatory and Mauna Kea Observatories. The work interfaces with surveys and missions like Sloan Digital Sky Survey, Two Micron All Sky Survey, Wide-field Infrared Survey Explorer, Galaxy And Mass Assembly, and Dark Energy Survey, and draws theoretical context from collaborations with groups connected to Princeton University, Harvard University, University of Chicago, University of Cambridge, and University of Tokyo.

Data and Methodology

Data sources combine redshift measurements from facilities such as Arecibo Observatory, Very Large Array, Green Bank Telescope, and spectroscopic campaigns tied to Keck Observatory and Very Large Telescope. Distance indicators include the Tully–Fisher relation calibrated with data from Spitzer Space Telescope and Hubble Space Telescope, the Fundamental Plane as used by teams at European Southern Observatory, and Type Ia supernovae samples linked to work by the Carnegie Supernova Project, Supernova Legacy Survey, and groups at Lawrence Berkeley National Laboratory. Methodologies employ flow-modeling algorithms influenced by analyses from Max Planck Institute for Astrophysics, reconstruction techniques like Wiener filtering used by researchers at University of Oxford and Rutgers University, and Bayesian frameworks developed in collaboration with scientists at Columbia University and University of Pennsylvania.

Major Releases and Catalogs

Releases aggregate thousands of galaxy distances and velocities into public products used by many groups. Catalog versions were produced with iterative improvements similar in scale to releases from 2MASS Redshift Survey teams and cross-referenced with datasets such as IRAS Point Source Catalog Redshift Survey, 6dF Galaxy Survey, Galaxy Zoo classifications, and the Cosmic Microwave Background dipole reference from COBE and Planck. The compilations are incorporated into analyses by researchers at National Aeronautics and Space Administration Jet Propulsion Laboratory, Space Telescope Science Institute, Max Planck Institute for Astronomy, and the International Centre for Radio Astronomy Research.

Key Scientific Results

The program has constrained bulk flows, anisotropic expansion signatures, and mass-density reconstructions, informing debates involving groups from Princeton University, MIT, University of California, Berkeley, and University of Oxford. Findings bear on measurements of the Hubble constant debated among teams from SH0ES, Carnegie Hubble Program, and analyses associated with Planck Collaboration and Dark Energy Survey. Work has shed light on structures like the Shapley Supercluster, Local Supercluster, and the influence of the Great Attractor region, with results compared against simulations by researchers at Max Planck Institute for Astrophysics, Los Alamos National Laboratory, Argonne National Laboratory, and groups using codes developed at Lawrence Berkeley National Laboratory.

Collaborations and Instruments

Collaborations span institutions including University of Hawaii, University of Michigan, University of Pennsylvania, University of Toronto, Princeton University, and observatories such as W. M. Keck Observatory, Gemini Observatory, and Subaru Telescope. Instruments contributing data include receivers at Arecibo Observatory, optical spectrographs on Keck Observatory and Very Large Telescope, imaging from Hubble Space Telescope and Spitzer Space Telescope, and radio resources like the Very Large Array and Green Bank Telescope. These efforts are coordinated with survey infrastructures like Sloan Digital Sky Survey, Pan-STARRS, and follow-up networks involving European Southern Observatory staff and personnel from Carnegie Institution for Science.

Limitations and Systematic Uncertainties

Limitations arise from selection effects tied to catalogs such as Two Micron All Sky Survey and surface-brightness biases familiar to teams working on Sloan Digital Sky Survey and 6dF Galaxy Survey. Systematics include calibration uncertainties comparable to those debated by SH0ES and Planck Collaboration teams, Malmquist bias well-studied by researchers at Harvard University and University of Cambridge, and cosmic variance issues examined by simulation groups at Max Planck Institute for Astrophysics and Institute for Advanced Study. Distance indicator scatter from Tully–Fisher analyses involves methods developed at Carnegie Institution for Science and groups collaborating with Space Telescope Science Institute.

Impact on Cosmology and Large-Scale Structure

The catalogues and analyses inform studies of dark matter distribution, structure formation, and cosmological parameters used by collaborations like Planck Collaboration, Dark Energy Survey, Baryon Oscillation Spectroscopic Survey, and theoretical work at Perimeter Institute for Theoretical Physics and Institute for Advanced Study. Results are used to validate numerical simulations produced by teams at CERN, Max Planck Institute for Astrophysics, National Center for Supercomputing Applications, and Los Alamos National Laboratory, and to compare inferred flows with predictions from models by researchers at California Institute of Technology and Princeton University.

Category:Astronomical surveys