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

We all expect data collection to start in the summer of 2022, which will lead to discoveries through the telescope. James Webb† But in the meantime, the astrophysicist push the tools at their disposal to go even further back into the past of the observable cosmos, in search of the first galaxies and the first supermassive black holes† We can convince ourselves of this today with two publications, one in Astrophysical Journal and the other in Monthly Notices of the Letters of the Royal Astronomical Society

Astrophysicists report the discovery of a star called HD1 which is the farthest discovered so far since it has a z-record value, the amount introduced by cosmologists to speak of a spectral redshift where the Hubble-Lemaître law associates this shift with a distance. It is also the oldest object detected since according to the equations of the general relativity and the standard cosmological model strongly supported by, among other things, data from the Planck satellite Re cosmic rays (and despite the tension between this data and that of the supernovas for the estimation of theaccelerating expansion of the universe observable), HD1 would be seen as it was about 13.5 billion years ago, i.e. only about 300 million years after the big bang

A quasar?

As explained in a press release from Center for Astrophysics | Harvard & Smithsonian in the United States, HD1 was discovered after more than 1,200 hours of observation with the Japanese Subaru ground-based telescope in Hawaii and the telescope Prospect (abbreviation of English Visible and infrared research telescope for astronomy) of the’ESOand in space the deceased the spitzer space telescope

It was very difficult to find HD1 among more than 700,000 objects » explains Yuichi Harikane in this press release, astronomer at the University of Tokyo who discovered the galaxy. The researcher adds: The color red of HD1 matched surprisingly well with the features expected from a galaxy of 13.5 billionlight yearswhich gave me a bit of goosebumps when I found it. The astrophysicists then made observations using theAtacama Large Millimeter/submillimeter Array (Alma) to confirm the distance of HD1, which is about 100 million light-years away from GN-z11, the current confirmed holder of the record for the most distant galaxy

Two things about HD1 need to be established even more firmly. First of all, the distance, and the intention is to do that by observing it with the James-Webb. But also its exact nature, because astrophysicists are not yet very sure whether they are observing a regular galaxy or a galaxy quasar with a supermassive black hole that would already contain about 100 million masses solar cells, which would be spectacular for a galaxy observed so shortly after the Big Bang. The supermassive black hole of our Milky Way currently contains only 4 million, but it is true that in the case of M87* that’s just over 6 billion solar masses.

Or population III stars?

In fact, talking about an ordinary galaxy is not correct, and astrophysicists are even considering one more exotic than the sighting of the most distant quasar yet discovered. Indeed, HD1 is very brilliant in terms ofultravioletthe researchers had first put forward the hypothesis that they were observing a galaxy with an outbreak ofstarsgalaxy star burst in English) like the ones we already know. But the estimate of the star formation rate needed to Brightness of HD1 implies that the galaxy would form more than 100 new stars each year, which is 10 times more than theoretically expected from starburst galaxies based on the observed stars.

However, as the astrophysicist explains: Fabio Pacucci stationed at Center for Astrophysics | Harvard & Smithsonianlead author of the study published in Mnras and co-author of the paper in ApJ: The very first population of stars to form in the Universe was more massive, brighter and hotter than modern stars. If we assume that the stars produced in HD1 are these first stars, say from People III, then its properties can be more easily explained. In fact, the stars of the people III are able to produce more UV light than normal stars, which could explain HD1’s extreme ultraviolet brightness.

This is another reason to impatiently await the James-Webb sightings.

The telescopes atop Mauna Kea, like this one, including the Keck Observatory telescopes shown in this video, allow us to probe the secrets of the cosmos. To get a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Automatic translation”. Choose “French”. Explore Documentary Films

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

Article by Laurent Sacco published on 14/12/2012

A group of astronomers have discovered 7 of the most distant galaxies known, observed over a period between 350 and 600 million years after the Big Bang. One of them may even have a record. Hubble may show it when the cosmos was only 380 million years old.

Astronomers have the Hubble ultra-deep field (HUDF). From 2003 to 2004, the Hubble instruments observed for several hours, spanning a duration of a total of 11 days, a small area of ​​the celestial vault in the constellation Oven. The astrophysicists had thus obtained an image in the visible in which both were present galaxies nearest and oldest known at that time. In 2009, the arrival of the Wide angle camera 3 (WFC3) aboard Hubble had enabled observations in infrared, revealing galaxies that were even older and difficult to see because of their low luminosity and greater redshift.

A group of astronomers just published an article about: arxiv with observations of part of the HUDF in the near infrared for 6 weeks, from August to September 2012.

The site Du Big Bang au Vivant is a French-language multiplatform project on the cosmology contemporary. Hubert ReevesJean Pierre Luminet and other researchers answer questions there using videos. © ECP Group, www.dubigbangauvivant.comYoutube

The balance ofHubble ultra-deep field 2012 has arrived

The harvest turned out to be good as the researchers obtained more accurate measurements and more solid with regard to galaxies observed when the age of the observable universe was no more than 600 million years. Now that the observable cosmos is estimated to be 13.7 billion years old, new Hubble images reveal 7 galaxies as our space and the matter it contains only 4% of their current age, in the words of the researchers.

Sightings still match the big bang

These 7 galaxies are said to have an age between 350 and 600 million years after the birth of the observable universe, i.e. at the time when the first stars and galaxies reionized the universe, according to information recently derived from the cosmic rays† One of these galaxies is particularly interesting and it is not unknown. It is about UDFj-39546284

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

UDFj-39546284 could be observed when only 380 million years have passed since theepisode fossil radiation. If so, it’s further away than we first thought and even holds the distance record. Technically, the redshift, z, was initially thought to be around 10, while it appears to be 11.9.

The 2012 observation campaign of the Hubble ultra-deep field has not only pushed the boundaries of the observable universe in the infrared even further with Hubble. The images and measurements obtained also show a very young cosmos in formation, such as it has not been in billions of years, and in full agreement with the theory of the big bang† They give us a taste of what the telescope should reveal to us James Webb in a few years, with much more detail.

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