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Image caption This star died just 520 million years after the Big Bang

A giant supernova explosion at the very edge of the observable universe appears to be the most distant event recorded by a telescope.

Astronomers believe that the death of this star, photographed by the American orbital observatory SWIFT, occurred just 520 million years after the Big Bang, in which our Universe was born.

This means that the light radiation from the dying star took 13.14 billion years to reach Earth.

The results of this research are published in the scientific journal Astrophysical Journal.

The discovered phenomenon was designated GRB 090429B. The letters GRB are short for gamma-ray burst, which is how astronomers refer to such objects.

X-ray of the Universe

These bursts of gamma rays usually accompany extremely violent stellar processes, such as the end of life of giant stars.

“It was probably a huge star, with about 30 times the mass of our Sun,” says team leader Dr. Antonino Cucchiara from the University of California, Berkeley.

“We do not yet have sufficient data to classify this star as a so-called Population III type star, that is, to the very first generation of stars that appeared in our Universe,” the scientist believes, “but we are certainly observing one of the earliest stages of star formation.” .

These bursts occur within a very short time, but their afterglow sometimes lasts for several days, which makes it possible to observe the development of the process using other telescopes and determine the distance to the gamma-ray burst.

Launched in 2004, the Swift satellite has the ability to quickly, in less than a minute, optically and X-ray identify bursts. Among his discoveries are powerful, sometimes multiple X-ray bursts in afterglows, as well as the detection of afterglows even before the end of the actual gamma ray emission.

Race for antiquity

Astronomers are now competing to see who will record the most distant, and therefore the most ancient, object in the Universe.

The famous Hubble Space Telescope has much more powerful instruments for observing such distant objects, which were brought on board by American astronauts in 2009.

How does a gamma-ray burst (GRB) occur?

NASA scientists studying images taken by the Hubble Telescope have already observed galaxies that are approximately the same distance from us as the gamma-ray object GRB 090429B.

Astronomers are interested in these extremely distant stars and star clusters because they expand our understanding of how the universe evolves.

Stars of the first generation attract special attention. These bright blue variables arose from molecular clouds that formed in the early stages shortly after the Big Bang.

These huge pulsating stars had a very short and rapid development cycle - only a few million years, generating heavy elements during their death.

Their harsh ultraviolet radiation led to the reionization of the surrounding nebulae, consisting mainly of hydrogen, stripping electrons from atoms, which in turn generated the extremely rarefied intergalactic plasma that surrounds the current generation of stars in our Galaxy.

According to Dr. Cucchiara, the gamma-ray burst GRB 090429B is unlikely to be one of the very first stars in the Universe. It is likely that even before this there were several generations of stars about which we still know nothing.

British and Italian engineers took part in the creation of the Swift orbital telescope. It carries a British X-ray camera that detects gamma-ray bursts, as well as components of an ultraviolet optical telescope.

The science

A newly discovered celestial object is vying for the title of the most distant observable space object in the Universe from us, astronomers reported. This object is a galaxy MACS0647-JD, which is located 13.3 billion light years from Earth.

The universe itself is believed to be 13.7 billion years old, so the light we see from this galaxy today is from the very beginning of the cosmos.

Scientists observe the object using NASA space telescopes "Hubble" And "Spitzer", and these observations were made possible with the help of a natural cosmic “magnifying lens”. This lens is actually a huge cluster of galaxies whose combined gravity warps space-time, producing what is called gravitational lens. When light from a distant galaxy passes through such a lens on its way to Earth, it is amplified.

Here's what a gravitational lens looks like:

“Such lenses can magnify the light of an object so much that no human-made telescope can do it.”, - speaks Marc Postman, an astronomer at the Space Telescope Science Institute in Baltimore. - Without such magnification, it takes a Herculean effort to see such a distant galaxy."

The new distant galaxy is very small, much smaller than our Milky Way- said the scientists. This object, judging by the light that has reached us, is very young; it came to us from an era when the Universe itself was at the very early stage of its development. It was only 420 million years old, which is 3 percent of its modern age.

The small galaxy is only 600 light years wide, but as you know, the Milky Way is much larger - 150 thousand light years wide. Astronomers believe that the galaxy MACS0647-JD eventually merged with other small galaxies to form a larger one.

Cosmic merger of galaxies

"This object may be one of many building blocks of some larger galaxy,- say the researchers. – Over the next 13 billion years, it could have undergone dozens, hundreds or even thousands of mergers with other galaxies or their fragments."

Astronomers continue to observe even more distant objects as their observing techniques and instruments improve. The previous object to hold the title of the most distant galaxy observed was galaxy SXDF-NB1006-2, which is located 12.91 billion light-years from Earth. This object was seen using telescopes "Subaru" And "Kek" in Hawaii.

The Hubble Orbital Telescope, launched in 1990, has become the main instrument of earthlings, expanding the visible boundaries of the Universe. The headlines “astronomers have found the most distant galaxy” have become familiar to the media and scientific publications, because it is indeed possible to find the most distant object at least every day. It may seem that such discoveries do not bring a qualitative breakthrough: the more powerful we take binoculars outside the city, the farther we see.

However, this analogy is not entirely appropriate here. Taking more powerful binoculars, we continue to see essentially the same objects - fields, rivers, forests, buildings. All this grows, moves, stands and does not fall according to laws long known to us.

The “edge” visible today contains objects that emitted light just hundreds of millions of years after the Big Bang. At that time, the Universe was just beginning to take shape. Therefore, when discovering the most distant galaxies, we try to understand not “what’s next?”, but “how did it all begin?”

Redshift

Universe line Redshift is the ratio of the magnitude of the shift of the spectral line to the longer wavelength side to the wavelength in the laboratory reference frame.

For objects that emitted light at the dawn of the Universe, this shift is several times greater than the wavelength itself

The Universe is constantly expanding, and the further an object is observed on a large scale, the faster it moves away from us. Therefore, the most convenient measure of distance is the assessment of the redness of an object caused by the Doppler effect. The most distant galaxy until recently corresponded to a redshift of z=8.6. She was born 600 million years after the Big Bang.

The period from 150 to 800 million years after the Big Bang refers to the so-called reionization period, when the first stars and galaxies ionized the intergalactic gas.

In a paper published in the journal Nature, astronomers led by Richard Bowens of Leiden University report the discovery of an even more distant galaxy with a redshift of about 10. The galaxy UDFj-39546284 was spotted in 2009, just three months after the Hubble telescope A wide-angle camera UDFj-39546284 is installed. The faint speck visible in the deep sky is nothing more than a compact galaxy consisting of young blue stars. The light we see from it is emitted just 480 million years after the Big Bang.

“These observations give us the best look at the earliest objects that have been found,” explained Richard Bowens.

The galaxy whose light reached us is too small and young to have a spiral shape or other features. Scientists have found that the galaxy was inhabited by stars 100-200 million years old. They were formed from gas collected around clumps of mysterious dark matter.

According to the researchers, during the observed era, the young Universe was experiencing a kind of baby boom: in the period from 480 to 650 million years after the Big Bang, the number of stars increased by one order of magnitude. “The frantic rate at which stars were being born tells us that if we look a little further back, we will see much more dramatic changes that occurred during the formation of the very first galaxies,” said Garth Illingworth of the University of California, Santa Cruz.

Having passed the z=10 mark, astronomers approached the “edge of the edge.” The first 500 million years (at z from 1000 to 10) after the Big Bang remain a blank spot in the hierarchical model of galaxy formation accepted today - from star clusters to elliptical and spiral galaxies. Galaxy UDFj-39546284 was discovered in the farthest infrared wavelengths visible to the Hubble telescope. Scientists hope to look further into the very early years of the Universe with the help of the James Webb Telescope.

“We went back in time, came very close to the first galaxies, which we believe formed about 200 - 300 million years after the Big Bang,” RIA Novosti quotes one of the authors of the work, Garth Illingworth. The unique object turned out to be UDFj-39546284 - a record-breaking distant galaxy that was distinguished by a relatively low rate of star formation. A comparison of data about it with information about other relatively closer and “older” galaxies showed that the rate of star formation in galaxies has increased tenfold in just 170 million years.

"This is amazing growth over a period that is only 1% of the current age of the universe," says Illingworth. According to scientists, these data are consistent with a hierarchical picture of galaxy formation, in which galaxies grow and merge under the influence of the gravity of dark matter. The galaxy discovered by scientists is much smaller and lighter than modern spiral galaxies. So, our Galaxy is about 100 times more massive.

The search for increasingly distant cosmic objects is helping astronomers peer into the distant past of the Universe. Because the speed of light is finite, we see distant galaxies as they were in the distant past. Astronomers observe the UDFj-39546284 galaxy as it was when the age of the Universe was only 480 million years.

The main indicator of the distance to distant galaxies is the red shift - a shift of lines in the spectrum due to the Doppler effect. The greater the redshift, the farther away the cosmic object is, since with distance, according to Hubble's law, the escape velocity of galaxies increases. According to the authors of the discovery of the most distant galaxy, its redshift may be 10.3. However, these data are not final, since at the present stage of development of astronomy, accurately measuring the redshift is an extremely difficult task. “Until the redshift is measured using spectroscopic methods, it remains just a candidate, albeit a good candidate,” astrophysicist Sergei Popov from the Sternberg Astronomical Institute commented on the discovery.

If the redshift of the open galaxy really turns out to be in the region of 9 - 10, then the object will be recognized as the most ancient in the Universe. In the meantime, this title was held by the galaxy UDFy-38135539, located 13 billion light years from Earth. It was discovered in October 2010 by astronomers from the European Southern Observatory (ESO). The redshift of this galaxy turned out to be 8.5549, and we see it as it was approximately 600 million years ago.

Studying the most distant galaxies may reveal objects billions of light years away, but even with perfect technology, the spatial gap between the most distant galaxy and the Big Bang will remain vast.

Looking into the Universe, we see light everywhere, at all distances that our telescopes can look at. But at some point we will come across limitations. One of them is imposed by the cosmic structure that forms in the Universe: we can only see stars, galaxies, etc., only if they emit light. Without this, our telescopes cannot see anything. Another limitation when using forms of astronomy other than light is the limit on how much of the Universe has been accessible to us since the Big Bang. These two quantities may not be related to each other, and it is on this topic that our reader asks us a question:

Why is the redshift of the CMB in the range of 1000, although the highest redshift of any galaxy we have seen is 11?

The entire set of what we know, see, observe, and interact with is called the “observable universe.” There are likely even more regions of the Universe beyond, and over time we will be able to see more and more of these regions as light from distant objects finally reaches us after a journey of billions of years through space. We can see what we see (and more, not less) due to a combination of three factors:

• A finite amount of time has passed since the Big Bang, 13.8 billion years.


• The speed of light, the maximum speed for any signal or particle moving through the Universe, is finite and constant.


• The very fabric of space has been stretching and expanding since the Big Bang.

What we see today is the result of these three factors, together with the original distribution of matter and energy operating according to the laws of physics throughout the history of the Universe. If we want to know what the Universe was like at any early point in time, we just need to observe what it is like today, measure all the related parameters, and calculate what it was like in the past. To do this we will need a lot of observations and measurements, but Einstein's equations, although so difficult, are at least unambiguous. The resulting results result in two equations, known as the Friedmann equations, and every student of cosmology faces the task of solving them directly. But, to be honest, we were able to make some amazing measurements of the parameters of the Universe.

By looking towards the north pole of the Milky Way Galaxy, we can peer into the depths of space. This image contains hundreds of thousands of galaxies, and each pixel is a different galaxy.

We know how fast it is expanding today. We know what the density of matter is in any direction we look. We know how many structures form at all scales, from globular clusters to dwarf galaxies, from large galaxies to galaxy groups, clusters and large-scale filamentary structures. We know how much normal matter, dark matter, dark energy, and also smaller components such as neutrinos, radiation, and even black holes are in the Universe. And only from this information, extrapolating back in time, can we calculate both the size of the Universe and the rate of its expansion at any moment in its cosmic history.

Logarithmic graph of the size of the observable Universe versus age

Today, our observable Universe extends approximately 46.1 billion light years in all directions from our point of view. At this distance is the starting point of an imaginary particle that set off at the moment of the Big Bang and, traveling at the speed of light, would arrive to us today, 13.8 billion years later. In principle, at this distance all the gravitational waves left over from cosmic inflation - the condition that preceded the Big Bang, set up the Universe and provided all the initial conditions - were generated.

Gravitational waves created by cosmic inflation are the oldest signal that humanity could possibly detect. They were born at the end of cosmic inflation and at the very beginning of the hot Big Bang.

But there are other signals left in the Universe. When it was 380,000 years old, residual radiation from the Big Bang stopped scattering from free charged particles as they formed neutral atoms. And these photons, after forming atoms, continue to be redshifted along with the expansion of the Universe, and can be seen today using a microwave or radio antenna/telescope. But due to the rapid rate of expansion of the Universe in the early stages, the "surface" that "glows" to us with this residual light - the cosmic microwave background - is only 45.2 billion light years away. The distance from the beginning of the Universe to the place where the Universe was after 380,000 years is equal to 900 million light years!

Cold fluctuations (blue) in the CMB are not colder per se, but simply represent areas of increased gravitational pull due to increased density of matter. Hot (red) regions are hotter because the radiation in these regions lives in a shallower gravitational well. Over time, denser regions are more likely to grow into stars, galaxies and clusters, while less dense regions are less likely to do so.

It will be a long time before we find the most distant galaxy in the Universe that we have discovered. Although simulations and calculations show that the very first stars could have formed 50-100 million years after the beginning of the Universe, and the first galaxies after 200 million years, we have not yet looked that far back (although there is hope that after the launch next year James Webb Space Telescope, we can do it!). Today, the cosmic record is held by the galaxy shown below, which existed when the Universe was 400 million years old - this is only 3% of its current age. However, this galaxy, GN-z11, is located only 32 billion light-years away: that's about 14 billion light-years from the “edge” of the observable Universe.

The most distant galaxy discovered: GN-z11, photo from the GOODS-N observation carried out by the Hubble telescope.

The reason for this is that in the beginning the rate of expansion dropped very quickly over time. By the time galaxy Gz-11 existed as we see it, the Universe was expanding 20 times faster than it is today. When the CMB was emitted, the Universe was expanding 20,000 times faster than it is today. At the time of the Big Bang, as far as we know, the Universe was expanding 10 36 times faster, or 1,000,000,000,000,000,000,000,000,000,000,000,000 times faster than it is today. Over time, the rate of expansion of the Universe has greatly decreased.

And this is very good for us! The balance between the primary expansion rate and the total amount of energy in the Universe in all its forms is perfectly maintained, up to the error of our observations. If there had been even a little more matter or radiation in the universe early on, it would have collapsed back billions of years ago and we wouldn't exist. If there was too little matter or radiation in the universe early on, it would expand so quickly that particles would not be able to meet each other to even form atoms, let alone more complex structures such as galaxies, stars, planets and people . The cosmic story that the Universe tells us is a story of extreme balance, thanks to which we exist.

The intricate balance between the rate of expansion and the overall density of the Universe is so delicate that even a deviation of 0.00000000001% in either direction would render the Universe completely uninhabitable for any life, stars or even planets at any given time.

If our best current theories are correct, then the first true galaxies should have formed between 120 and 210 million years ago. This corresponds to a distance from us to them of 35-37 billion light years, and a distance from the most distant galaxy to the edge of the observable Universe of 9-11 billion light years today. This is extremely far away, and speaks to one surprising fact: the Universe expanded extremely quickly in the early stages, and today it is expanding much more slowly. 1% of the age of the Universe is responsible for 20% of its total expansion!

The history of the Universe is full of fantastic events, but since inflation ended and the Big Bang occurred, the rate of expansion has fallen rapidly, and is slowing down as density continues to decrease.

The expansion of the Universe stretches the wavelength of light (and is responsible for the redshift we see), and the large speed of this expansion is responsible for the large distance between the microwave background and the most distant galaxy. But the size of the Universe today reveals something else astonishing: incredible effects that have occurred over time. Over time, the Universe will continue to expand more and more, and by the time it is ten times its age today, the distances will have increased so much that we will no longer be able to see any galaxies except members of our local group, even with a telescope equivalent to Hubble. Enjoy all that is visible today, the great diversity of what is present on all cosmic scales. It won't last forever!