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article imageGalaxies formed one billion years earlier than previously thought

By Tim Sandle     Dec 31, 2019 in Science
The detection of a distant galaxy, far more massive than the Milky Way reveals that the 'cores' of massive galaxies had already formed 1.5 billion years after the Big Bang, this is some 1 billion years earlier than calculations suggested.
The new insight into the age of galaxies is based on readings taken using telescopes located at the W.M. Keck Observatory in Hawaii. In addition, an advanced instrument called MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration), was fitted to the Keck I telescope.
This instrument enabled astronomers to obtain a two-micron measurement in the near-infrared spectrum. This confirmed that light from the galaxy was emitted 1.5 billion years after the Big Bang (a very short time interval in the history of the universe). Previously data indicated that galaxies were first formed 2.5 billion years after the Big Bang. Detailed measurements of the expansion rate of the universe place the Big Bang at around 13.8 billion years ago, which hence this is considered the age of the universe.
The galaxy examined is a so-termed 'quenching galaxy', located in the Subaru/XMM-Newton Deep Field. Most galaxies are either 'alive' (blue) or 'dead' (red): Red sequence galaxies are generally non-star-forming elliptical galaxies with little gas and dust, while blue cloud galaxies tend to be dusty star-forming spiral galaxies. A quenching galaxy is a galaxy in the process of dying, where start formation is suppressed.
As lead researcher Francesco Valentino (U.S. National Institutes of Natural Sciences) explains: "The suppressed star formation tells you that a galaxy is dying, sadly, but that is exactly the kind of galaxy we want to study in detail to understand why quenching occurs."
The researchers hope that by using the new methodology they will be able to search for more massive quenching galaxies in the far distant universe and gain a greater insight into galaxy formation.
The new time-point discovery has been reported to The Astrophysical Journal. The research paper is titled "Stellar Velocity Dispersion of a Massive Quenching Galaxy at z = 4.01."
More about Big bang, Galaxies, Milky way, Astronomy
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