‘James Webb Space Telescope’ Updates Record of Farthest Galaxy in Observation History | sorae Portal of the universe

in the spacethe galaxy” was born after how long was the universe born?

In order for a galaxy to be born, a celestial body with a high material density, it is necessary for the materials to attract each other by gravity and to assemble. The initial stage of mutual attraction between matter is thought to arise from slight differences (fluctuations) in the density of matter after the birth of the universe. The time between the birth of the universe and the birth of galaxies is a parameter that determines the degree of difference in the density of matter in the early universe.

However, it is not easy to observe the universe several hundred million years after its birth. The act of “observing the past universe” is the same as “observing a farther universe”, and the apparent brightness of celestial bodies becomes darker. Also, the wavelength of light emitted by galaxies in the early universe is lengthened by the expansion of the universe, and ultraviolet and visible light become infrared. Very little infrared light passes through Earth’s atmosphere, so observations of galaxies in the early universe are impossible without launching a high-performance space telescope.

The operation began in July 2022James Webb Space Telescope” is an infrared telescope launched with one of the main purposes of observing the early Universe. There are several observing programs for the early universe, but this timeJADES (JWST Advanced Deep Extragalactic Survey)” announced great results.

The JADES program is an international research group made up of over 80 astronomers from 10 countries.NIR Cam” and near infrared spectrometer “NIRS specwe aim to make detailed observations of the early Universe.

The observed area this time is “Hubble Ultra Deep Field” and surroundings. As the name suggests, this term refers to the region of the sky observed by the Hubble Space Telescope. The apparent area of ​​the Hubble Ultra Deep Field, chosen as the region with no bright stars in the field of view, is smaller than a 1 mm square piece of paper at 1 m away, but contains about 10,000 star objects, including some of the most distant objects ever observed at the time.

[▲ Figura 1: Dati spettrali dell’intera regione osservata dal programma JADES e quattro oggetti trovati particolarmente distanti. Le lunghezze d’onda della rottura di Lyman sono spostate verso il rosso a lunghezze d’onda maggiori, consentendo un’accurata determinazione della distanza. (Credito immagine: NASA, ESA, CSA, M. Zamani (ESA/Webb), Leah Hustak (STScI))]

The JADES program initially made observations using NIRCam for a mission time of 10 days or more. The mission time itself is about the same as for the Hubble Space Telescope, but the wavelength has increased from 4 to 9 and the observing range is about 15 times wider. As a result, it has been found that there are about 100,000 celestial bodies in the observed range, and some of them have been speculated to be extremely distant.

A detailed spectral analysis of around 250 objects was then performed over a mission time of around 28 hours using NIRSpec. As a result, we observed “Lyman breaks” in which specific infrared wavelengths are dark, and found that the wavelengths differ depending on the celestial body. Through observations of the Lyman breakup, not only has this object been shown to be a distant galaxy, but also the distance can be estimated from the degree of wavelength variation. As a result, it was found that there are four particularly extremely distant galaxies with a redshift value of z=10 or more.

【▲ Figure 2: Four particularly distant galaxies observed by the JADES program. Three of them have higher values ​​than the most distant galaxies known so far. The other was a distant object that had been observed in the past and was reobserved. (Image credit: Riri Ayae)]

of the four galaxiesJADE-GS-z13-0」「JADE-GS-z12-0」「JADE-GS-z11-0surpassed GN-z11, which previously held the record for farthest galaxy.

Also,”JADE-GS-z10-0‘ is a new observation of ‘UDFj-39546284’ and more accurate measurements have been made than those observed by the Hubble Space Telescope. It was named UDFj-39546284 when it was first observed by the Hubble Space Telescope and its redshift was calculated to be z=10.3±0.8. This meant that it was the most distant object at the time of observation. Subsequent observations also claimed a value of z = about 11.9, indicating that it exists further out. There was some discussion as to its identity. The JADES program has now confirmed that the initial observation results were correct, assuming that UDFj-39546284 is the same object as JADES-GS-z10-0.

The JADES program has announced very good results this time, but the program has only just begun. The JADES program has a total observation period of just over a month over two years, so further results are expected to be announced.

Source

• BE Robertson, et.al. – “Discovery and properties of the first galaxies with ascertained distances”. (arXiv)
• Taddeo Cesari – “NASA’s Webb hits new milestone in search of distant galaxies.” (NASA/James Webb Space Telescope)
• Linhua Jiang, et al. – “Evidence for GN-z11 as a luminous galaxy at redshift 10.957”. (astronomy of nature)
• RJ Bouwens, et al. – “Photometric Constraints on the Redshift of z~10 candidate UDFj-39546284 from deeper WFC3/IR+ACS+IRAC observations on the HUDF”. (The letters from the astrophysicist diary)
• Gabriel B. Brammer, et al. – “A tentative detection of an emission line at 1.6 μm for candidate z~12 UDFj-39546284”. (The letters from the astrophysicist diary)

Text: Riri Ayae