When did the stars first form after the big bang created the universe?



For the first time, astronomers have detected a signal from stars emerging in the early universe. Using a radio antenna not much larger than a refrigerator, the researchers discovered that ancient suns were active within 180 million years of the Big Bang.

The astronomers, from Arizona State University (ASU), the Massachusetts Institute of Technology (MIT) and the University of Colorado at Boulder, made the discovery with their Experiment to Detect the Global EoR (Epoch of Reionization) Signature (EDGES) project, funded by the National Science Foundation (NSF). They reported their findings in the March 1 issue of Nature.

Astronomers have been in the process of acquiring important data on early signals from the universe shortly after the Big Bang in search of the earliest formation of large-scale structures in the cosmos, e.g., stars, galaxies, quasars, and so on.

In only 180 million years after the Big Bang, apparently, astronomers from Arizona State University (ASU), the Massachusetts Institute of Technology (MIT), and the University of Colorado at Boulder discovered important objects through the EDGES experiment or the Experiment to Detect the Global Epoch of Reionization Signature project.

They made the discovery with funding by the National Science Foundation. Thank you much, NSF, this is barely possible without you. The astronomers discovered a small window into the early universe at only T=180 million years, where they could see stars forming.

Arizona State University Astronomer Judd Bowman said, “Finding this miniscule signal has opened a new window on the early universe… Telescopes cannot see far enough to directly image such ancient stars, but we’ve seen when they turned on in radio waves arriving from space.”

The accepted models of the early Big Bang universe depict stars that were “massive, blue and short-live.” The Cosmic Microwave Background Radiation or CMB is a radiation permeating the entire universe, which is the remnants of the Big Bang throughout the universe. It can be picked up as radio signals, like the static on those old televisions in movies.

Peter Kurczynski, the National Science Foundation Program Director, explained, “There is a great technical challenge to making this detection… Sources of noise can be 10,000 times brighter than the signal — it’s like being in the middle of a hurricane and trying to hear the flap of a hummingbird’s wing.”

The detection of the early universe in any clarity is hard. It is as if having really bad distance vision and trying to shoot a bird in flight. You will have some problems. Apparently, the early universe stars emitted lots of ultraviolet light, which gives a clue.

Free-floating hydrogen atoms absorbed the CMB photons or light particles in the early universe. MIT Haystack Observatory Astronomer Alan Rogers said, “You start seeing the hydrogen gas in silhouette at particular radio frequencies… This is the first real signal that stars are starting to form, and starting to affect the medium around them.”

In the data, there is a clear signal from the early universe. The CMB intensity dropped, ultraviolet light ripped free-floating hydrogen atoms into parts, and the electrons floating away. This is called ionization.

As the early stars died, other large-scale astronomical objects kept the ionization in-process while heating the free hydrogen and getting rid of the signal. That happened at T=250 million years.

Kurczynski said, “This discovery opens a new chapter in our understanding of how the world we see came into being… Indirectly, they have seen farther than even the Hubble Space Telescope to find evidence of the earliest stars.”

By Scott Douglas Jacobsen

References

Discover Magazine

National Science Foundation.

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