James Webb observes the oldest galaxies

How did the universe begin?

What was the universe like in the distant past? How did the universe begin? It will take at least several decades to find the above answers and fully understand the universe in the past. But thanks to the James Webb Space Telescope, which is extremely sensitive to infrared light, we’re getting closer to the answer.

Astronomers explain that, as planned before launch, the James Webb Space Telescope completely changes its view of the universe. In particular, the telescope above, which specializes in infrared observations, shows the distant universe and suggests that stars may have formed earlier than we would theoretically expect.

Which galaxy is officially the oldest?

The oldest galaxy before James Webb Space Telescope observations is GN-z11, an irregular galaxy in the constellation Ursa Major observed by the Hubble Space Telescope. It is officially known as the most distant galaxy in the solar system to date and has a notable redshift of 11.09. Convert that to a distance, about 13.4 billion light years, a galaxy only about 400 million years after the universe was born.

Astronomers use the James Webb Space Telescope to capture features of ancient objects that appear only in galaxies that formed shortly after the Big Bang (consisting mainly of light elements and low-mass stars) and in galaxies that are even older and they continue to form. record.

However, many galaxies predicted to be ancient are known to require further investigation, such as a galaxy predicted to be very close after 13.8 billion years turns out to be a galaxy that formed much later.

Discovery of primitive galaxies about 50 million years older than the oldest officially identified galaxies

An international astronomy research team led by Professor Tommaso Trio of the University of California, Los Angeles (UCLA) reports the observation of GLASS-z12, a galaxy that occurred about 350 million years after the formation of the universe. (High resolution image shortcut)

GLASS-z12 (labelled 2), a galaxy about 350 million years after the formation of the universe © NASA, ESA, CSA, Tommaso Treu (UCLA), image processing: Zolt G. Levay (STScI)

A research team led by Professor Trieu has used the James Webb Space Telescope to capture ancient galaxies around Abell 2744 (also called the Pandora Cluster). The oldest galaxies are not found within galaxy clusters, but exist billions of light years behind them.

The galaxy marked (1) is a galaxy approximately 450 million years after the Big Bang, and the galaxy marked (2) is a galaxy just 350 million years after the Big Bang. Both galaxies are very close in time to the Big Bang, which occurred 13.8 billion years ago. In particular, the elongated galaxy marked with (1) shows very small dimensions compared to our Milky Way.

GLASS-z12 (Galaxy 2 in focus), a galaxy about 350 million years after the formation of the Universe © NASA, ESA, CSA, Tommaso Treu (UCLA), image processing: Zolt G. Levay (STScI)

The image above shows an image of Abell 2744 taken with the near-infrared camera of the James Webb Space Telescope (NIRCam), along with a scale tape (the measure of the angle of the Earth when looking at the sky, measured in seconds of arc, 1/1 of a degree). 3600, the angular diameter of the full moon is approximately 0.5°), the north/east compass arrow shows direction when looking at the sky and reverses direction when looking down. Also, the colors show the NIRCam filters used to collect the light, and each color represents the color of visible light used to represent the infrared light passing through that filter.

GLASS-z12 was discovered last July (this galaxy was called GLASS-z13 at the time of discovery) © JWST / NASA, ESA, CSA

Indeed, the galaxy above was discovered at the edge of the “Abell 2744” galaxy cluster last July. At the time of discovery, it was named “GLASS-z13” because it was expected to have a redshift greater than z = 13.1, but subsequent studies revealed that the redshift of the overlying galaxy was approximately z = 12.4 (+ 0.1-0.3). , stating “It has been renamed “GLASS-z12”. The galaxy above was discovered together with GLASS-z10, which is expected to compete with GN-z11, the oldest galaxy. (Links to related articles)

The research team explains that the highly sensitive NIRCam instrument is completely changing our view of the universe and that the discovery of an object that existed just a few hundred million years after the Big Bang indicates that the galaxy above it may have had a beginning early. . than he thought. Indeed, for the galaxies mentioned to exist, the formation must begin only 100 million years after the Big Bang, and through this, it can be predicted that the dark age of the universe, which was composed of gas and dark matter without any light, completed much earlier than expected.

GLASS-z12 was discovered last July (this galaxy was called GLASS-z13 at the time of discovery) © JWST / NASA, ESA, CSA

The research team led by Professor Trieu speculated that the two galaxies discovered this time could be low-mass galaxies composed of extremely bright and hot Population III stars. These first generation stars consisted only of primordial hydrogen and helium, before the appearance of the heavy elements resulting from stellar nuclear fusion, and are celestial bodies that have never been observed.

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