“James Webb Space Telescope” updates the record of the farthest galaxy in observation history | sorae Portal site to the universe

[▲ Artist’s impression of the James Webb Space Telescope observing deep space (Credit: AlejoMiranda)]

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

In order for a galaxy, a celestial body with a high material density, to be born, it is necessary for the materials to attract each other by gravity and assemble. It is believed that the initial stage of mutual attraction between matter stems from slight differences (fluctuations) in matter density following 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 matter density in the early universe.

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

Operation started 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 observation programs for the early universe, but this timeJADES (JWST Advanced Deep Extragalactic Survey)” program has announced great results.

The JADES program is an international research team consisting of more than 80 astronomers from 10 countries.NIRCam” and near-infrared spectrometer “NIRSpecwe aim to make detailed observations of the early Universe.

The area observed this time is the “Hubble Ultra Deep Field” and its 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 a region without bright stars in the field of view, is smaller than a 1 mm square piece of paper at 1 m away, but contains an estimated 10,000 stars. objects, including some of the most distant objects ever observed at the time.

[▲ Figure 1: Spectral data of the entire region observed by the JADES program and four objects found to be particularly distant. The wavelengths of the Lyman break are redshifted to longer wavelengths, allowing accurate distance determination. (Image credit: NASA, ESA, CSA, M. Zamani (ESA/Webb), Leah Hustak (STScI))]

The JADES program first carried out observations using NIRCam over a mission time of 10 days or more. The mission time itself is regarding the same as the Hubble Space Telescope, but the wavelength has increased from 4 to 9, and the range of observation is regarding 15 times wider. As a result, it was found that there are regarding 100,000 celestial bodies in the observed range, and it was speculated that some of them were extremely distant.

A detailed spectral analysis of regarding 250 objects over a mission time of regarding 28 hours was then performed 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 break, it was not only proved that this object is a distant galaxy, but also the distance can be estimated from the degree of wavelength variation. As a result, it was found that four galaxies in particular exist extremely far away 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 re-observed. (Image Credit: Riri Ayae)]

of the four galaxiesJADES-GS-z13-0」「JADES-GS-z12-0」「JADES-GS-z11-0” surpassed the value of GN-z11, which had previously held the record for the most distant galaxy.

Also,”JADES-GS-z10-0‘ is a re-observation of ‘UDFj-39546284’, and more accurate measurements were 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. In later observations, a value of z = regarding 11.9 was also claimed, which indicates that it exists farther away, but on the contrary, there is a counterargument that it is misidentifying a closer object with a special spectrum. There was some debate regarding 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 great results this time, but the program has just started. The JADES program has a total observation period of a little over one month over two years, so it is expected that further results will be announced.

Source

• B. E. Robertson, et.al. – “Discovery and properties of the earliest galaxies with confirmed distances”. (arXiv)
• Thaddeus Cesari – “NASA’s Webb Reaches New Milestone in Quest for Distant Galaxies”. (NASA/James Webb Space Telescope)
• Linhua Jiang, et.al. – “Evidence for GN-z11 as a luminous galaxy at redshift 10.957”. (Nature Astronomy)
• RJ Bouwens, et al. – “Photometric Constraints on the Redshift of z~10 candidate UDFj-39546284 from deeper WFC3/IR+ACS+IRAC observations over the HUDF”. (The Astrophysical Journal Letters)
• Gabriel B. Brammer, et.al. – “A Tentative Detection of an Emission Line at 1.6 μm for the z~12 Candidate UDFj-39546284”. (The Astrophysical Journal Letters)

Text: Riri Ayae