15 spectacular photos from the Dark Energy Camera

From high atop a mountain in the Chilean Andes, the Dark Energy Camera has snapped more than one million exposures of the southern sky. The images have captured around 2.5 billion astronomical objects, including galaxies ...

Center of the Coma cluster explored with AstroSat

Using India's AstroSat spacecraft, astronomers have investigated a central field of a cluster of galaxies known as the Coma cluster. Results of the study, presented in a paper published September 13 on arXiv.org, deliver ...

No trace of dark matter halos

According to the standard model of cosmology, the vast majority of galaxies are surrounded by a halo of dark matter particles. This halo is invisible, but its mass exerts a strong gravitational pull on galaxies in the vicinity. ...

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Galaxy groups and clusters

Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation. They form the densest part of the large scale structure of the universe. In models for the gravitational formation of structure with cold dark matter, the smallest structures collapse first and eventually build the largest structures, clusters of galaxies. Clusters are then formed relatively recently between 10 billion years ago and now. Groups and clusters may contain from ten to thousands of galaxies. The clusters themselves are often associated with larger groups called superclusters.

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