A team of astronomers has used data collected by a trio of NASA's orbital telescopes in order to weigh an ancient galaxy cluster dating back to 3.8 billion years after the universe was created. Known as IDCS J1426.5+3508 (IDCS 1426), the cluster is the largest structure of its kind ever discovered in this period. Located 10 billion light-years from Earth, it boasts a mass of 500 trillion times that of our Sun – the equivalent of around 1,000 Milky Ways.
Astronomers believe that an analysis of clusters such as IDCS 1426 could lead to a better understanding of just how these colossal structures came to form in the early universe. The study made use of data collected by NASA's Spitzer and Hubble telescopes, as well as the Chandra X-ray Observatory and the Keck Observatory situated in Mauna Keo, Hawai'i.
The team was able to calculate the galaxy cluster's mass using three independent techniques. One method saw astronomers observe the imprint that the mass of IDCS 1426 made on the cosmic microwave background radiation, while another measured the mass needed to confine the X-ray emitting gas to the cluster. Finally, the team observed the extent to which the light from galaxies behind IDCS 1426 was distorted by the cluster's mass.
Under current models, it is expected that a galaxy cluster would take several billion years to fully coalesce. However, the vast distances between Earth and IDCS 1426 means that we are observing a version of the cluster as it existed when the universe was only 3.8 billion years old, meaning that the cluster is still in a relatively early stage of its evolutionary process.
According to data harvested by the telescopes, IDCS 1426 is composed of roughly 90 percent dark matter. The observations also highlighted a number of bright X-ray sources that appear to have shifted roughly 100,000 light years away from the cluster's center.
This could hint at a cataclysmic collision with another embryonic galaxy cluster, which the team believes could have occurred some 500 million years previously. This collision could have spurred an increase in the cluster's evolutionary rate, a theory which is supported by the otherwise smooth distribution of gas throughout the rest of the cluster.
However, despite this growth spurt, the galaxy cluster was recorded as having lower than expected quantities of elements heavier than hydrogen and helium. This could be the result of the cluster's relatively juvenile nature, having yet to undergo enough supernova explosions to enrich its gas.
"The presence of this massive galaxy cluster in the early Universe doesn't upset our current understanding of cosmology," states Anthony Gonzalez of the University of Florida in Gainesville, Florida, who co-authored a paper on the research. "It does, however, give us more information to work with as we refine our models."
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