a galaxy observed just 300 million years after the Big Bang?

We are all looking forward to the start of data collection by the summer of 2022, which will lead to telescope discoveries. James Webb. But in the meantime astrophysicists continue to use the tools at their disposal to the limit of their ability to go even further into the past of observable space, in search of the first galaxies and the first supermassive black holes. We can verify this by two publications today, one of which Astrophysical journal and the other in Monthly Notices of Letters from the Royal Astronomical Society.

Astrophysicists announce discovery star named HD1, which is the farthest ever discovered to date because it has a z-record value, a quantity introduced by cosmologists to talk about a spectral redshift with the Hubble-Lemaitre law relating this shift to distance. It is also the oldest discovered object since, according to equations general relativity and standard cosmological model convincingly confirmed, among other things, by the data Planck’s satellite concerning cosmic radiation (and despite the contradiction between these data and the data supernovae for rateaccelerating the expansion of the universe observable), HD1 could be seen as it was about 13.5 billion years ago, i.e. big Bang.


As explained in a press release from center of astrophysics | Harvard and the Smithsonian in the USA, HD1 was discovered after more than 1200 hours of observations with the Japanese Subaru telescope on the ground in Hawaii and the telescope Vista (abbreviation from English. Visible and infrared survey telescope for astronomy) belonging’ECOand in space a dead man spitzer space telescope.

It was very difficult to find HD1 among more than 700,000 objects. ”, Yuichi Harikane explains in this press release, astronomer at the University of Tokyo, which opened galaxy. The researcher adds: color HD1’s red color matched surprisingly well the performance expected of a galaxy 13.5 billion years old.light yearswhich gave me goosebumps when I found it. The astrophysicists then made observations usingAtacama Large Millimeter/Submillimeter Array (Alma) to confirm the distance to HD1, which is about 100 million light-years further than GN-z11, the current confirmed record holder for the most distant galaxy..

Two things about the HD1 have yet to be established more firmly. First, his distance, and this is planned to be done by observing him with the help of James-Webb. But also its exact nature, because astrophysicists don’t yet know very well whether they are observing an ordinary galaxy or quasar with a supermassive black hole that would already contain about 100 million masses solar panels, which would have been impressive for a galaxy seen shortly after the Big Bang. Our supermassive black hole Milky Way currently contains only 4 million, but it is true that in the case M87* that’s just over 6 billion solar masses.

Or population III stars?

In fact, it is incorrect to talk about an ordinary galaxy, and astrophysicists consider even more exotic than observing the most distant quasar discovered to date. Indeed, because HD1 is very bright in the ultraviolet, the researchers hypothesized for the first time that they are observing a flare galaxy.stars (galaxy in English), like the ones we already know. But the star formation rate estimate needed to explain brightness from HD1 implies that the galaxy will form more than 100 new stars each year, which is 10 times more than is theoretically expected from starburst galaxies based on observables.

However, as the astrophysicist explains Fabio Pacucci placed in center of astrophysics | Harvard and the Smithsonianlead author of a study published in Mnras and co-author of an article in ApJ: “ The very first population of stars to form in the universe was more massive, brighter, and hotter than today’s stars. If we assume that the stars born in HD1 are these first stars, let’s say People III, then its properties could be explained more simply. In fact, the stars people III able to produce more ultraviolet light than normal stars, which could explain HD1’s extreme ultraviolet luminosity. »

This is another reason to look forward to the James-Webb observations.

Telescopes atop Mauna Kea like this one, including the Keck Observatory telescopes shown in this video, allow us to explore the mysteries of space. For a fairly accurate French translation, click on the white box in the lower right corner. After that, English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Select “French”. © Explore Documentaries

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

Article Laurent Sacco published on 12/14/2012

A team of astronomers have discovered 7 of the most distant known galaxies observed between 350 and 600 million years after the Big Bang. One of them may even become a champion. Hubble shows what is possible when the cosmos was only 380 million years old.

Astronomers studied Hubble Ultra Deep Field (HUDF). From 2003 to 2004, the Hubble instruments observed for several hours, for a total of 11 days, a small region of the sky located in constellation ovens. Thus, astrophysicists obtained an image in the visible range, on which galaxies the closest and oldest known at the time. In 2009 the arrival Wide Camera 3 (WFC3) aboard Hubble made it possible to make observations in infraredfinding even older galaxies that are difficult to observe due to their low luminosity and higher redshift.

A group of astronomers has just published a paper on archive covering observations of part of the HUDF in the near-infrared range for 6 weeks, from August to September 2012.

Du Big Bang au Vivant website is a French-language multi-platform project on cosmology modern. Hubert Reeves, Jean-Pierre Lumine and other researchers there answer questions using video. © EKP Group, www.dubigbangauvivant.comYouTube

Balance sheetHubble Ultra Deep Field 2012 has arrived

The harvest turned out to be good, as the researchers got more accurate measurements and more. solid relative to the galaxies observed when the age of the observable universe did not exceed 600 million years. Considering that the age of the observed space is estimated at 13.7 billion years, the new Hubble images reveal 7 galaxies to us, while our space and to matter According to the researchers, it contains only 4% of their current age.

Observations are still consistent with the Big Bang

These 7 galaxies should be between 350 and 600 million years old after the birth of the observable universe, so at the time when the first stars and the first galaxies reionized the universe, according to information recently obtained from cosmic radiation. One of these galaxies is especially interesting and famous. this UDFj-39546284.

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

UDFj-39546284 could be observed when only 380 million years had passed since its origin.episode fossil radiation. If so, then it is farther than we first thought, and even holds the record for the longest distance. Technically, its redshift z was originally thought to be 10, although it turned out to be 11.9.

2012 observation campaign Hubble Ultra Deep Field Hubble not only further pushed the boundaries of the observable universe in the infrared. The resulting images and measurements also show the formation of a very young cosmos that has not been seen for billions of years, and in full agreement with the theory big Bang. They give us an idea of ​​what the telescope should reveal to us. James Webb in a few years, with much more details.

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