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2w ago

ALMA Detects Overheated Gas in a Distant Protocluster, Challenging Cluster Formation Models

A strong thermal Sunyaev–Zel'dovich signal reveals extreme early heating that researchers suggest may be driven by active black holes and will be probed with follow‑up observations.

Artist’s impression of a forming galaxy cluster in the early universe: radio jets from active galaxies are embedded in a hot intracluster atmosphere (red), illustrating a large thermal reservoir of gas in the nascent cluster. Image via Lingxiao Yuan/ The University of British Columbia.
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Overview

  • The peer-reviewed Nature study published January 5 reports the earliest direct detection of hot intracluster gas, seen at redshift ~4.3 about 12.4 billion light-years away.
  • The intracluster medium in SPT2349-56 is at least five times hotter than predicted and, in parts, hotter than many clusters in the present-day universe.
  • Researchers used ALMA to measure the thermal Sunyaev–Zel'dovich effect, which traces hot electrons by their imprint on the cosmic microwave background.
  • The compact core spans roughly 500,000 light-years, hosts more than 30 active or starburst galaxies, and is forming stars thousands of times faster than the Milky Way.
  • The team points to energetic feedback from embedded supermassive black holes and intense starbursts as a plausible heating source and is planning multiwavelength follow-ups to test the mechanisms and prevalence.