NASA weighs collosal, ancient galaxy cluster
A team of astronomershas used data collected by a trio of NASA's orbital telescopes inorder to weigh an ancient galaxy cluster dating back to 3.8 billionyears after the universe was created. Known as IDCS J1426.5+3508(IDCS 1426), the cluster is the largest structure of its kind everdiscovered in this period. Located 10 billion light-years from Earth,it boasts a mass of 500 trillion times that of our Sun – theequivalent of around 1,000 Milky Ways.
Astronomers believethat an analysis of clusters such as IDCS 1426 could lead to a betterunderstanding of just how these colossal structures came to form inthe early universe. The study made use of data collected by NASA'sSpitzer and Hubble telescopes, as well as the Chandra X-rayObservatory and the Keck Observatory situated in Mauna Keo, Hawai'i.
The team was able tocalculate the galaxy cluster's mass using three independenttechniques. One method saw astronomers observe the imprint that themass of IDCS 1426 made onthe cosmic microwave background radiation, while another measured themass needed to confine the X-ray emitting gas to the cluster.Finally, the team observed the extent to which the light fromgalaxies behind IDCS 1426 was distorted by the cluster's mass.
Under current models,it is expected that a galaxy cluster would take several billion yearsto fully coalesce. However, the vast distances between Earth and IDCS1426 means that we are observing a version of the cluster as itexisted when the universe was only 3.8 billion years old, meaningthat the cluster is still in a relatively early stage of itsevolutionary process.
According to dataharvested by the telescopes, IDCS 1426 is composed of roughly 90percent dark matter. The observations also highlighted anumber of bright X-ray sources that appear to have shifted roughly100,000 light years away from the cluster's center.
This could hint at acataclysmic collision with another embryonic galaxy cluster, whichthe team believes could have occurred some 500 million yearspreviously. This collision could have spurred an increase in thecluster's evolutionary rate, a theory which is supported by theotherwise smooth distribution of gas throughout the rest of thecluster.
However, despite thisgrowth spurt, the galaxy cluster was recorded as having lower thanexpected 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 thismassive galaxy cluster in the early Universe doesn't upset ourcurrent understanding of cosmology," states Anthony Gonzalez of theUniversity of Florida in Gainesville, Florida, who co-authored apaper on the research. "It does, however, give us more informationto work with as we refine our models."