Once Again, Galaxies Look Surprisingly Mature Shortly After the Beginning of the Universe

The workings of the Universe.
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fred8615
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Once Again, Galaxies Look Surprisingly Mature Shortly After the Beginning of the Universe

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A young galaxy with the catchy, roll-off-the-tongue name A1689-zD1 has experts in galactic formation talking. Recent observations show that this galaxy, seen as it would have looked just 700 million years after the Big Bang, is larger than initially believed, with significant outflows of hot gas from its core, and a halo of cold gas emanating from its outer rim. A1689-zD1 is considered representative of young ‘normal’ galaxies (as opposed to ‘massive’ galaxies), and the new observations suggest that the adolescence of normal galaxies may be more rambunctious than previous models suggest.

A1689-zD1 was first observed in 2007 by the Hubble Space Telescope, and at the time it was a contender for the most distant galaxy yet discovered (a record that has been surpassed several times over, most recently in April 2022). Indeed, it is so distant that the only reason it is possible to get such a good view of it at all is that it is conveniently located behind a much nearer galaxy, whose gravitational interaction with spacetime creates a lensing effect, magnifying the distant A1689-zD1 behind it. The Spitzer Space Telescope was able to observe the galaxy alongside Hubble, but the clearest images of the galaxy were obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), which specializes in wavelengths invisible to the naked eye and well suited to enormously distant objects.

The ALMA data tells a story buried in the details that Hubble and Spitzer were unable to see.

“The emission from the carbon gas in A1689-zD1 is much more extended than what was observed with Hubble Space Telescope,” says Seiji Fujimoto, a postdoctoral fellow at the Niels Bohr Institute, “and this could mean that early galaxies are not as small as they appear. If, in fact, early galaxies are larger than we previously believed this would have a major impact on the theory of galaxy formation and evolution in the early Universe.”

Read more: https://www.universetoday.com/156359/on ... -universe/
Frederick J. Barnett
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