intergalactic medium
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| intergalactic medium | |
|---|---|
| Name | Intergalactic medium |
| Density | Very low (≈10^−6 to 10^−4 particles/cm³) |
| Temperature | 10^4–10^7 K |
| Composition | Primarily hydrogen and helium, trace metals |
| Notable | Filamentary cosmic web, warm-hot intergalactic medium |
intergalactic medium The intergalactic medium is the diffuse matter that occupies the space between galaxies and permeates the Local Group, Virgo Cluster, Coma Cluster, and larger structures such as the Laniakea Supercluster and the Great Attractor. It links environments studied by missions like Hubble Space Telescope, Chandra X‑ray Observatory, Rosat, and observatories such as Very Large Array, Atacama Large Millimeter/submillimeter Array, and Sloan Digital Sky Survey through processes investigated in projects including Planck (spacecraft), Galaxy And Mass Assembly (GAMA), and surveys by the European Southern Observatory.
Introduction
The diffuse baryonic reservoir between galaxies has been probed by instruments like Keck Observatory, Subaru Telescope, James Webb Space Telescope, and facilities including Arecibo Observatory, Green Bank Telescope, Fermi Gamma‑ray Space Telescope, and theoretical groups at institutions such as Institute for Advanced Study, Max Planck Society, and Harvard–Smithsonian Center for Astrophysics. Historically, inquiries into the intergalactic medium trace through work by researchers associated with Royal Astronomical Society, American Astronomical Society, and seminal studies at Princeton University, California Institute of Technology, University of Cambridge, and Massachusetts Institute of Technology.
Composition and Physical Properties
The medium is dominated by ionized hydrogen and helium with traces of heavier elements produced by processes in galaxies like Milky Way, Andromeda Galaxy, Messier 87, NGC 1275, and distributed by feedback from events such as Type Ia supernova, Type II supernova, Active galactic nucleus, and winds driven by phenomena cataloged in surveys like Sloan Digital Sky Survey. Chemical enrichment links to stellar populations in hosts studied at European Southern Observatory, Space Telescope Science Institute, Max Planck Institute for Astrophysics, and galaxy evolution programs at Carnegie Institution for Science and National Aeronautics and Space Administration. Thermal states vary from cool filaments traced with Lyman-alpha forest absorption in spectra from Hubble Space Telescope and Keck Observatory to warm‑hot phases (WHIM) detected in X‑rays by Chandra X‑ray Observatory and XMM-Newton and studied by teams at Columbia University and University of Chicago.
Distribution and Large-Scale Structure
Matter in the intergalactic medium arranges into the cosmic web with filaments, sheets, and voids connecting nodes like Coma Cluster, Perseus Cluster, Virgo Cluster, Shapley Supercluster, and regions cataloged by Two Micron All Sky Survey. Mapping efforts by Sloan Digital Sky Survey, 2dF Galaxy Redshift Survey, Dark Energy Survey, and projects like Euclid (spacecraft) and Large Synoptic Survey Telescope reveal correlations with dark matter structures modeled by groups at Lawrence Berkeley National Laboratory, Argonne National Laboratory, and Fermi National Accelerator Laboratory. The interplay between baryons and halos around objects such as Milky Way, Andromeda Galaxy, Magellanic Clouds, Messier 31, and satellites mapped in programs led by Space Telescope Science Institute informs studies of accretion, filaments, and voids highlighted by collaborations at National Radio Astronomy Observatory.
Thermodynamics and Ionization Processes
Heating and cooling mechanisms involve photoionization from sources including Quasar, Seyfert galaxy, Blazar, and background radiation measured by Planck (spacecraft) and missions affiliated with European Space Agency. Shock heating from mergers of structures like Bullet Cluster and feedback from Active galactic nucleus jets observed in Messier 87 affect temperature distributions examined by teams at Max Planck Institute for Extraterrestrial Physics and NASA Goddard Space Flight Center. Recombination and collisional ionization processes studied in laboratories associated with Lawrence Livermore National Laboratory and theoretical work at Princeton University set ionization fractions that influence diagnostics used by observers at Harvard University and University of California, Berkeley.
Role in Galaxy Formation and Evolution
Gas accretion from the medium fuels star formation in galaxies such as Milky Way, Andromeda Galaxy, Triangulum Galaxy, and systems in catalogs compiled by Messier, New General Catalogue, and groups at Max Planck Institute for Astronomy. Outflows powered by Type II supernova and Active galactic nucleus feedback redistribute metals into the medium, a process explored by researchers at University of Cambridge, Yale University, University of Toronto, and Imperial College London. Interactions with circumgalactic media around hosts in programs like COS-Halos and Sloan Digital Sky Survey influence morphological transformation seen in clusters such as Virgo Cluster and Coma Cluster and studied by consortia at Space Telescope Science Institute.
Observation and Detection Methods
Probes include absorption-line spectroscopy of background sources like Quasar, Gamma-ray burst, Seyfert galaxy, and surveys by Hubble Space Telescope, Keck Observatory, and Very Large Telescope. Emission detections in X‑ray and ultraviolet use Chandra X‑ray Observatory, XMM-Newton, FUSE, and instruments developed by teams at European Space Agency, NASA, and Jet Propulsion Laboratory. Radio investigations by Very Large Array, Square Kilometre Array, Atacama Large Millimeter/submillimeter Array, and long‑baseline interferometry projects at National Radio Astronomy Observatory complement absorption work from facilities like Green Bank Telescope and Arecibo Observatory.
Theoretical Models and Simulations
Cosmological simulations by groups at Max Planck Institute for Astrophysics, Princeton University, Harvard–Smithsonian Center for Astrophysics, Lawrence Berkeley National Laboratory, Kavli Institute for Cosmology, and collaborations producing codes such as those used in projects like IllustrisTNG, EAGLE (simulation), and Millennium Simulation model the medium’s evolution. These models integrate physics from high‑energy contexts studied at CERN, cooling and chemistry informed by research at NASA Ames Research Center, and feedback prescriptions developed in partnership with institutions including Stanford University, Columbia University, and University of California, Santa Cruz.