Galaxy Cluster

Galaxy Cluster

Galaxy clusters are structures in the universe consisting of hundreds of galaxies bound by gravity. Galaxy clusters are much larger than galaxy groups. One of the key features of clusters is the Intracluster medium or ICM. The ICM consists of gas between the galaxies and has a temperature on the order of 7-9 keV. Clusters of galaxies should not be confused with star clusters such as galactic clusters and open clusters, which are structures within galaxies, as well as globular clusters, which typically orbit galaxies.

Notable galaxy clusters in the relatively nearby Universe include the Virgo cluster, Fornax Cluster, Hercules Cluster, and the Coma Cluster. A very large aggregation of galaxies known as the Great Attractor, dominated by the Norma cluster, is massive enough to affect the local expansion of the Universe (Hubble flow). Notable galaxy clusters in the distant, high-redshift Universe include SPT-CL J0546-5345, the most massive galaxy cluster ever found in the early Universe. In the last few decades, they are also found to be relevant sites of particle acceleration, a feature that has been discovered by the observing non-thermal diffuse radio emissions as radio halos and radio relics. With Chandra X-ray Observatory structures like cold front, shock front, minihalo have also been found in many galaxy clusters.

Read more about Galaxy Cluster:  Basic Properties, Composition

Famous quotes containing the words galaxy and/or cluster:

    for it is not so much to know the self
    as to know it as it is known
    by galaxy and cedar cone,
    as if birth had never found it

    and death could never end it:
    Archie Randolph Ammons (b. 1926)

    the green hells of the sea
    Where fallen skies and evil hues and eyeless creatures be;
    On them the sea-valves cluster and the grey sea-forests curl,
    Splashed with a splended sickness, the sickness of the pearl;
    Gilbert Keith Chesterton (1874–1936)