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JWST ‘Little Red Dots’ Are Young Black Holes Shrouded in Gas Cocoons

JWST spectra reveal dense ionized cocoons that reprocess light, hiding high‑energy emission.

Overview

  • The Nature study led by University of Copenhagen researchers analyzed JWST infrared spectra for about 30 objects and concludes the sources are rapidly accreting supermassive black holes.
  • Reinterpreting the emission lowers inferred black hole masses by roughly 10–100 times to a few million to about 10 million solar masses.
  • The cocoons absorb ultraviolet and X‑ray output and re‑emit at redder wavelengths, explaining the dots’ color and compact appearance.
  • These objects appear a few hundred million years after the Big Bang and largely fade from view by roughly one billion years, consistent with a brief growth phase near the Eddington limit.
  • Hundreds of candidates remain to be tested, with teams planning broader spectral samples and X‑ray/radio follow‑up as alternative models, including massive Population III star scenarios, continue to be evaluated.