Mar 23, 2021 - Science

Scientists find a new way to map darker parts of the cosmic web

A scientific illustration showing the cosmic web connecting galaxies.
A scientific illustration showing the cosmic web connecting galaxies. Photo: ESO/NASA/Roland Bacon et al.

For the first time, scientists have mapped a part of the cosmic web connecting galaxies without using the light of bright galaxies known as quasars.

Why it matters: The method paves the way for future experiments that may allow scientists to unmask other darker parts of the cosmos and piece together what the early universe may have looked like.

What they did: The scientists behind the new study used the MUSE instrument on a telescope in Chile to capture the light of galaxies connected by the cosmic web of gas filaments spread through the universe.

  • The light captured as part of this study — accepted for publication in the journal Astronomy & Astrophysics — was emitted by galaxies about 2 billion years after the Big Bang.
  • "We think that the light we are seeing comes mainly from young galaxies, each containing millions of times fewer stars than our own Milky Way," one of the authors of the study Joop Schaye said in a statement.
  • "Such tiny galaxies were likely responsible for the end of the cosmic 'dark ages', when less than a billion years after the Big Bang, the universe was illuminated and heated by the first generations of stars."
  • The study also suggests these small galaxies helped spur on the evolution of the universe not long after it formed.

Background: Typically, scientists study the cosmic web by using bright quasars that effectively act as nodes, lighting up the gas of the web, making it visible to specialized instruments.

  • However, quasars are relatively rare, making this kind of study using dimmer light emitted by other, more plentiful galaxies intriguing for researchers mapping the cosmic web.
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