NAOJ: 'Cores' of Massive Galaxies Formed Soon After Big Bang

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NAOJ: 'Cores' of Massive Galaxies Formed Soon After Big Bang

Post by bystander » Thu Dec 19, 2019 8:06 pm

The 'Cores' of Massive Galaxies Had Already Formed 1.5 Billion Years after the Big Bang
National Astronomical Observatory of Japan | Subaru Telescope | W.M. Keck Observatory | 2019 Dec 19
fig1e[1].jpg
A blow-up of a small portion of the Subaru/XMM-Newton Deep Field. The red galaxy at
the center is a dying galaxy at 12 billion years ago. Astronomers measured the motion
of stars in the galaxy and found that the core of the galaxy is nearly fully formed.
(Credit: NAOJ)

A distant galaxy more massive than our Milky Way -- with more than a trillion stars -- has revealed that the 'cores' of massive galaxies in the Universe had formed already 1.5 billion years after the Big Bang, about 1 billion years earlier than previous measurements revealed. ...

Galaxies are broadly categorized as dead or alive: dead galaxies are no longer forming stars, while living galaxies are still bright with star formation activity. A 'quenching' galaxy is a galaxy in the process of dying -- meaning its star formation is significantly suppressed. Quenching galaxies are not as bright as fully alive galaxies, but they're not as dark as dead galaxies. Researchers use this spectrum of brightness as the first line of identification when observing the Universe.

The researchers used the telescopes at the W.M. Keck Observatory in Hawaii to observe a quenching galaxy in what is called the Subaru/XMM-Newton Deep Field. This region of the sky has been closely observed by several telescopes, producing a wealth of data for scientists to study. Tanaka and his team used an instrument called MOSFIRE on the Keck I telescope to obtain measurements of the galaxy. They obtained a two-micron measurement in the near-infrared spectrum, which the human eye cannot see, but it confirmed that the light from the galaxy was emitted just 1.5 billion years after the Big Bang. The team also confirmed that the galaxy's star formation was suppressed. ...

Stellar Velocity Dispersion of a Massive Quenching Galaxy at z = 4.01 ~ Masayuki Tanaka et al
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