Representation of the timeline of the universe over 13.7 billion years, and the expansion in the universe that followed. Credit: NASA/WMAP Science Team.

Shedding New Light on the Cosmic Dark Ages

Article Updated: 24 Dec , 2015


From a University of Cambridge press release:

Remnants of the first stars have helped astronomers get closer to unlocking the “dark ages” of the cosmos. A team of researchers from the University of Cambridge and California Institute of Technology are using light emitted from massive black holes called quasars to “light up” gases released by the early stars, which exploded billions of years ago. As a result, they have found what they refer to as the missing link in the evolution of the chemical universe.

The first stars are believed to hold the key to one of the mysteries of the early cosmos: how it evolved from being predominantly filled with hydrogen and helium to a universe rich in heavier elements, such as oxygen, carbon and iron.

However, although telescopes can detect light reaching Earth from billions of light-years away, enabling astronomers to look back in time over almost all of the 13.7-billion-year history of the universe, one observational frontier remains: the so-called “dark ages.” This period, lasting half a billion years after the Big Bang, ended when the first stars were born and is inaccessible to telescopes because the clouds of gas that filled the universe were not transparent to visible and infrared light.

“We have effectively been able to peer into the dark ages using the light emitted from a quasar in a distant galaxy billions of years ago. The light provides a backdrop against which any gas cloud in its path can be measured,” said Professor Max Pettini at Cambridge’s Institute of Astronomy (IoA), who led the research with PhD student Ryan Cooke.

Taking precision measurements using the world’s largest telescopes in Hawaii and Chile, the researchers have used Quasar Absorption Line Spectroscopy to identify gas clouds called ‘damped Lyman alpha systems’ (DLAs). Among the thousands of DLAs known, the team have succeeded in finding a rare cloud released from a star very early in the history of the universe.

“As judged by its composition, the gas is a remnant of a star that exploded as much as 13 billion years ago,” Pettini explained. “It provides the first analysis of the interior of one of the universe’s earliest stars.”

The results provide experimental observations of a time that has so far been possible to model only with computers simulations, and will help astronomers to fill gaps in understanding how the chemical universe evolved.

“We discovered tiny amounts of elements present in the cloud in proportions that are very different from their relative proportions in normal stars today. Most significantly, the ratio of carbon to iron is 35 times greater than measured in the Sun,” Pettini said. “The composition enables us to infer that the gas was released by a star 25 times more massive than the Sun and originally consisting of only hydrogen and helium. In effect this is a fossil record that provides us with a missing link back to the early universe.”

The study was published in Monthly Notices of the Royal Astronomical Society by Ryan Cooke, Max Pettini and Regina Jorgenson at the IoA, together with Charles Steidel and Gwen Rudie at the California Institute of Technology in Pasadena.

16 Responses

  1. Super Earth says:

    In the Dark Ages there were no galaxies, so there weren’t quasars…

    This is not directly analysing the gas from the Dark Ages, but gas clouds that are remnants from that epoch, right?

  2. Lawrence B. Crowell says:

    This is confusing, and the press release was not much better. My impression is that gas generated during the dark age is being illuminated by the quasar. So the gas measured is more contemporary, but it has not been adulterated by subsequent astrophysics since the dark age.


    • Uncle Fred says:

      So these clouds of gas have nothing to do with the Dark Ages? What came first, earliest stars or hungry, luminous supermassive black holes?

      I’m so confused here.


      • HeadAroundU says:

        I guess, stars. Then, there was article on UT about what was first, galaxies or black holes.

      • HeadAroundU says:

        Also, it was about supermassive ones, I guess. I guess, first stars could collapse into a black hole or not??? Any expert, please??? 😀

      • Torbjorn Larsson OM says:

        I believe that is the question. Naively these stars should be able to mature and/or grow to collapse, but not much is observed and known IIRC.

      • Torbjorn Larsson OM says:

        I interpret it as Lawrence. These clouds of gas originated in, and tell us about, the Dark Ages.

    • HeadAroundU says:

      Yeah, good point. At first, I was thinking that quasar was shooting back in time. :d

      • Lawrence B. Crowell says:

        As I said and Torbjorn Larsson OM agrees, this is the only way to interpret these results. If the gas has remained largely in the state is emerged from through the dark age its physical properties should tell us about the nucleosynthesis which went on there.

        The wording of the press release is somewhat ambiguous and can give the impression about a quasar illuminating material during the dark age.


  3. lars says:

    No disrespect to Ms. Atkinson, as she’s just reporting an interesting news article.

    But Mainstream Astrophysics has misinterpreted what Redshift is telling us.
    Quasars aren’t billions of light years away, they are quite close actually, it’s their large Redshift that has caused the distance misinterpretation problem.

    And another thing, there was no Big Bang, the universe has always been here.

    • Uncle Fred says:

      I smell a Plasma cosmologist.
      All your assertions are based on what observations?


    • Torbjorn Larsson OM says:

      Sorry, but *we know* that the standard cosmology is correct. Your cosmology must, to compete, explain all it does and some more. And you haven’t even presented _one_ reference here.

      Could we go back and discuss reality now, please? It is so much more exciting than people’s hallucinations. 😀

    • Hon. Salacious B. Crumb says:

      Just like the Etruscan chieftain, Lars Porsenna; you might put Rome under siege, but you’ll never take the city. Likewise with this nonsense.
      Really. It is the funniest thing I’ve read in ages!
      Thanks for the good giggle!

  4. Lawrence B. Crowell says:

    I wish people would get in line with the real stuff. This plasma cosmology stuff is at best amuzing and worse annoying. It is wrong. This little clip gives a 101-intro to big bang cosmology.


  5. rudeyd says:

    Huge stars came were 1st that exploded as Supernovas that created black holes that eventually merged stars as well as elements to form galaxies…….. right?
    Am I way off here?
    Just when you think you might have your head partially wrapped around the concept – poof, an article confuses the crap out of it.

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