THINGS (The HI Nearby Galaxy Survey)

THINGS (The HI Nearby Galaxy Survey)
Name	THINGS
Caption	VLA observations of nearby galaxies
Type	Radio interferometry survey
Site	Socorro, New Mexico
Operator	National Radio Astronomy Observatory
Wavelength	21 cm (HI line)
Telescope	Karl G. Jansky Very Large Array

THINGS (The HI Nearby Galaxy Survey) is a high-resolution 21-centimetre line survey of neutral hydrogen in nearby galaxies, designed to provide uniform, high-fidelity imaging for studies of galactic structure, kinematics, and interstellar medium processes. The survey targeted a representative sample of nearby disk, dwarf, and irregular systems to link observations of neutral hydrogen to star formation, dark matter, and galaxy evolution across environments. THINGS data have been integrated into comparative studies with multiwavelength programs and theoretical efforts across astrophysics.

Introduction

THINGS was motivated by the need for homogeneous, high angular resolution HI imaging to complement optical, infrared, and ultraviolet surveys such as Sloan Digital Sky Survey, Two Micron All Sky Survey, GALEX, and Spitzer Space Telescope programs. The survey built upon earlier work from facilities including the Westerbork Synthesis Radio Telescope, Arecibo Observatory, Effelsberg 100-m Radio Telescope, and precedent surveys like The HI Nearby Galaxy Survey (WHISP) and the LITTLE THINGS project to establish baselines for rotation curves and gas dynamics. Principal investigators and team members included researchers affiliated with institutions such as Max Planck Society, University of Cambridge, Harvard University, University of Groningen, and California Institute of Technology, enabling cross-collaboration with projects like THINGS follow-up studies and theoretical groups at Institute for Advanced Study, Harvard-Smithsonian Center for Astrophysics, and Princeton University.

Survey Design and Observations

THINGS used the Karl G. Jansky Very Large Array in multiple configurations to achieve spatial resolution matched to studies from instruments like Hubble Space Telescope and Chandra X-ray Observatory. The sample selection drew on catalogs compiled by teams working with Third Reference Catalogue of Bright Galaxies, Uppsala General Catalogue of Galaxies, NASA/IPAC Extragalactic Database, and legacy compilations by Bengt Gustafsson-era groups. Observations targeted galaxies spanning morphological types catalogued in systems used by Edwin Hubble and metrics developed at Royal Astronomical Society meetings, enabling cross-comparison with datasets from European Southern Observatory, Subaru Telescope, Keck Observatory, and the Anglo-Australian Telescope. Calibration strategies referenced standards maintained by National Radio Astronomy Observatory and leveraged correlator designs influenced by work at Bell Labs and instrumentation efforts from Associated Universities, Inc..

Data Reduction and Products

THINGS employed reduction pipelines that combined techniques from interferometry efforts at National Radio Astronomy Observatory, Max Planck Institute for Radio Astronomy, and software concepts pioneered in Astronomical Image Processing System and packages evolving from MIRIAD and CASA. Data products include data cubes, moment maps, rotation curves, and position-velocity diagrams useful to teams at Space Telescope Science Institute, European Space Agency, Jet Propulsion Laboratory, and university groups at University of California, Berkeley, University of Wisconsin–Madison, and University of Sydney. Ancillary products were matched to imaging from Hubble Space Telescope programs, spectrophotometry from Very Large Telescope, and catalogs maintained by Centre de Données astronomiques de Strasbourg. Data release policies aligned with practices at Smithsonian Institution and enabled reuse in studies hosted by Mikulski Archive for Space Telescopes and national archives run by Canadian Astronomy Data Centre.

Scientific Results

THINGS enabled precise rotation curve measurements that informed dark matter halo modeling frameworks developed at University of Toronto, University of California, Santa Cruz, and Rutgers University, challenging cuspy halo predictions from simulations at Princeton University and University of California, Santa Barbara. The survey constrained the relation between HI surface density and star formation traced by Spitzer Space Telescope infrared maps and GALEX ultraviolet imaging, yielding results cited by researchers at Max Planck Institute for Astrophysics, Lawrence Berkeley National Laboratory, and Johns Hopkins University. Studies of spiral structure, tidal features, and gas accretion tied THINGS measurements to works on galactic fountains and feedback by teams at University of Cambridge, Columbia University, and University of Michigan. Kinematic asymmetries and non-circular motions observed in THINGS galaxies informed models tested at Harvard University and the Kavli Institute for Theoretical Physics, while comparisons with CO surveys from Institut de Radioastronomie Millimétrique and Nobeyama Radio Observatory linked atomic and molecular phases in programs associated with National Astronomical Observatory of Japan and Osaka University.

Legacy and Impact

THINGS set a benchmark for spatially resolved HI studies that influenced surveys with the MeerKAT pathfinder, Australian Square Kilometre Array Pathfinder, and preparations for the Square Kilometre Array. The survey’s methodologies were adopted by consortia at South African Radio Astronomy Observatory, CSIRO Astronomy and Space Science, and teams at Netherlands Institute for Radio Astronomy. THINGS datasets continue to be used in investigations by groups at University of Oxford, University of Edinburgh, Yale University, and Imperial College London addressing baryonic Tully–Fisher relations, disk stability analyses, and multi-phase interstellar medium modeling in collaborations with researchers connected to Carnegie Institution for Science and Max Planck Institute for Astronomy.

Collaborations and Instrumentation

The THINGS collaboration brought together scientists from observatories and institutions such as National Radio Astronomy Observatory, Max Planck Institute for Astronomy, Space Telescope Science Institute, University of California, University of Bonn, and University of Leiden, coordinating observing time on the Karl G. Jansky Very Large Array and sharing expertise from instrumentation groups at Associated Universities, Inc., NRAO Electronics Division, and software teams that developed pipelines inspired by projects at Cornell University and University of Maryland. The project’s impact extended to education and training programs at University of Hawaii, Ohio State University, and Texas A&M University, and fostered cross-disciplinary links with computational centers at Argonne National Laboratory and Los Alamos National Laboratory.

Category:Astronomy surveys