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Un zoom montrant HD1 en fausse couleur. © Harikane et al., Nasa, EST and P. Oesch/Yale.

A galaxy seen only 300 million years after the Big Bang?

We all expect to start collecting data by the summer of 2022 that will lead to discoveries by the telescope. James Webb. But, in the meantime, the astrophysicists Continuing to push the tools at their disposal to their limits in order to go back to the past of the observable universe, in search of the first and first galaxies supermassive black holes. We can convince ourselves of this with two posts today, one in Astrophysical Journal and the other in Monthly notifications of letters of the Royal Astronomical Society.

Astrophysicists report the discovery of a star Named HD1 it is the farthest discovered so far since it has a z-value, which is the quantity that cosmologists have given to talk about the spectral redshift with the Hubble-Lemaître law linking this shift to distance. It is also the oldest object discovered since then according to Equations subordinate general relativity and the Standard Cosmic Model Strongly backed by, among other things, data from Planck satellite Concerning cosmic radiation (Despite the tension between this data and the data supernovae to estimateaccelerating the expansion of the universe observable), HD1 will be seen as it was about 13.5 billion years ago, which is only about 300 million years after the great explosion.


As explained in a press release from Astrophysics Center | Harvard and Smithsonian In the United States, HD1 was discovered after more than 1,200 hours of observation with the Japanese Subaru Telescope on the ground in Hawaii and the telescope vista (English abbreviation visible and infrared scanning telescope for astronomy) From’ESOAnd in the dead space Spitzer Space Telescope.

It was very difficult to find HD1 among more than 700,000 objects In this press release, Yuichi Harikane explains, astronomer At the University of Tokyo who discovered the galaxy. The researcher adds: The the color HD1’s red color matches surprisingly well the properties expected for a galaxy at 13.5 billion .light yearsWhich gave me goosebumps when I found it. Then astrophysicists made observations usingLarge Atacama Group Millimeter / Meter (Alma) to confirm the distance of HD1, which is more than 100 million light-years GN-z11, the current record holder for the farthest galaxy.

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Two things about HD1 have yet to be proven more firmly. First of all, after him, and it is planned to do so with his monitoring by James-Webb. but also its exact nature because astrophysicists do not yet know whether they are observing a normal galaxy or a galaxy quasar With a supermassive black hole that would already contain about 100 million masses Solar cells, which would be amazing for a galaxy observed shortly after the Big Bang. Our supermassive black hole Milky Way It currently contains only 4 million, but it is true that in the case of M87 * That’s just over 6 billion solar masses.

Or its three-star population?

In fact, talking about an ordinary galaxy is not true, astrophysicists are even thinking about more a stranger From observing the farthest quasar discovered so far. In fact, the HD1 is very impressive in the field ofultravioletthe researchers first put forward the hypothesis that they were observing a galaxy with an eruptionstars (star galaxy in English) like the ones we already know. But the estimation of the rate of star formation needs explanation brightness HD1 indicates that the galaxy will form more than 100 new stars each year, which is 10 times more than theoretically expected from starburst galaxies based on those observed.

However, as the astrophysicist explains Fabio Baccucci stationed in Astrophysics Center | Harvard and Smithsonianlead author of the study published in Mnras and co-author of the article in ApJ: “ The first group of stars that formed in the universe were much more massive, brighter, and hotter than modern stars. If we assume that the stars produced in HD1 are those first stars, for example third people, then its properties can be explained more easily. In fact, stars third people Capable of producing more ultraviolet light than normal stars, which could be responsible for HD1’s extreme ultraviolet brightness. »

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Here’s another reason to wait impatiently for James Webb’s feedback.

Telescopes atop Mauna Kea, like here, including the Keck Observatory telescopes shown in this video, allow us to investigate the mysteries of the universe. For a fairly accurate French translation, click the white rectangle at the bottom right. The English translation should then appear. Then click on the nut to the right of the rectangle, then click on “Subtitles” and finally on “Translate automatically”. Choose “French”. © Explore documentaries

Record: A galaxy 380 million years after the Big Bang?

Article from Laurent Sacco Posted on 12/14/2012

A group of astronomers has discovered 7 of the most distant galaxies known, which were observed over a period stretching between 350 and 600 million years after the Big Bang. Someone might own a record. Hubble shows this probably when the universe was only 380 million years old.

Astronomers were studying Hubble’s ultra-deep field (Hudf). From 2003 to 2004, Hubble instruments were observed for several hours, scattered over a Duration Total 11 days, a small region of the celestial vault located in the constellation Furnace. Thus, astrophysicists obtained an image in the visible that has both of them galaxies The earliest and oldest known at that time. In 2009, the arrival 3 . wide field camera (WFC3) aboard the Hubble telescope made possible infrared observations, revealing older galaxies that are difficult to observe due to their lower luminosity and greater redshift.

A group of astronomers just published an article about arxiv Coverage of observations of a portion of HUDF in the near infrared for 6 weeks, August-September 2012.

Du Big Bang au Vivant is a French-speaking multi-platform project on cosmology contemporary. Hubert ReevesAnd the Jean-Pierre Luminet Other researchers there answer questions using videos. © ECP Group, www.dubigbangauvivant.comYoutube

balance sheetHubble’s ultra-deep field 2012 arrived

The harvest turned out to be good as the researchers got more accurate measurements and more Solid With regard to galaxies observed when the age of the observable universe did not exceed 600 million years. With the observable universe estimated to be 13.7 billion years old, new Hubble images reveal us 7 galaxies while our space and ours Thing It contained only 4% of its current age, the researchers said.

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Observations are still consistent with the Big Bang

These seven galaxies will have ages between 350 and 600 million years after the birth of the observable universe, so by the time the first stars and first galaxies re-ionized the universe, according to information recently extracted from cosmic radiation. One of these galaxies is particularly interesting and is unknown. it’s a UDFj-39546284.

Almost two years ago, it was already presented as the farthest known galaxy, but the estimate of its age, and therefore its distance, remains uncertain. Another galaxy has been proposed for the title of the oldest and most distant: SXDF-NB1006-2.

UDFj-39546284 can be observed when only 380 million years have passed sinceepisode fossil radiation. If so, he’s farther than we initially thought, and even holds the distance record. Technically, its redshift, z, was initially thought to be close to 10, when it appears to be 11.9.

Monitoring campaign 2012 from Hubble’s ultra-deep field Not only did he push the boundaries of the visible-infrared universe even further with Hubble. The obtained images and measurements also show a very young universe in its formation stage, such that it was not billions of years ago, and in complete agreement with the theory of the great explosion. It gives us an idea of ​​what the telescope should reveal to us James Webb In a few years, in more detail.

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