When it comes to deep space observations, our cosmological insignificance seems to grow with the resolution of our telescopes\u2019 cameras. In the latest advance, astronomers constructed the deepest-ever images of Abell 3667, a massive galaxy cluster located 700 million light-years from Earth\u2014and most of the tiny dots you see represent entire galaxies.<\/p>\n
But the latest images of Abell 3667 also offer \u201cwhispering evidence of past galactic interactions,\u201d which astronomers document in detail in a paper published today in The Astrophysical Journal Letters<\/a>. The team, led by astronomers from Brown University, caught Abell 3677 at a particularly lustrous moment in space-time, during a merger of two of the clusters\u2019 brightest galaxies. The stellar union, resembling a starry bridge stretching across the cluster, generated powerful gravitational bursts that yanked away the occasional stray star from other galaxies.\u00a0<\/p>\n Together, these lone stars emit a faint glow known as intracluster light (ICL)\u2014and it\u2019s this phenomenon that researchers are investigating to explore Abell 3677\u2019s past. Specifically, it appears likely that Abell 3667 also formed from the rapid merger of two galaxy clusters, which previous X-ray and radio observations had predicted. This latest observation, however, represents the first ever optical evidence to support this idea.<\/p>\n<\/p>\n \u201cThis is the first time a feature of this scale and size has been found in a local galaxy cluster,\u201d Anthony Englert, study lead author, said in a statement<\/a>. \u201cWe knew that it was possible for a bridge like this to form between two galaxies, but it hadn\u2019t been documented anywhere before now. It was a huge surprise that we were able to image such a faint feature.\u201d<\/p>\n The team had an unusually long observation period for this project, which partly enabled them to construct such a detailed image. In addition to the intracluster light, the researchers captured faint, wispy puffs of cosmic dust called integrated flux nebulae<\/a>, seen as bluish ribbons of light streaking across the image.<\/p>\n \u201cIt was just a happy coincidence that so many people had imaged Abell 3667 over the years, and we were able to stack all of those observations together,\u201d Englert noted.<\/p>\n \u201cWhat we did is just a small sliver of what Rubin is going to be able to do. It\u2019s really going to blow the study of the [intracluster light] wide open.\u201d <\/p>\n