"We went back in time, came very close to the first galaxies, which we believe formed approximately 200 to 300 million years after the Big Bang," RIA Novosti quoted one of the authors of the work, Garth Illingworth, as saying. The unique object turned out to be UDFj-39546284 - a record-breaking distant galaxy, which was distinguished by a relatively low rate of star formation. 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.
"That's amazing growth over a period that's only 1% of the current age of the universe," says Illingworth. According to scientists, these data are consistent with the hierarchical picture of galaxy formation, according to which galaxies grow and merge under the influence of the gravity of dark matter. The galaxy found by scientists is much smaller and lighter than modern spiral galaxies. So, our galaxy is about 100 times more massive.
The search for more and more distant space objects helps astronomers look 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 universe was only 480 million years old.
The main indicator of the distance to distant galaxies is the redshift - the shift of lines in the spectrum due to the Doppler effect. The greater the redshift, the farther the space object, because 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 the development of astronomy, the exact measurement of redshift is an extremely difficult task. "Until the redshift is measured using spectroscopic methods, it remains just a candidate, although a good candidate," astrophysicist Sergei Popov of the Sternberg Astronomical Institute commented on the discovery.
If the redshift indicators of an open galaxy really turn 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 about 600 million years ago.
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 was, apparently, the most distant event recorded by the 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 from the dying star traveled to Earth for 13.14 billion years.
The results of this study are published in the scientific journal Astrophysical Journal.
The discovered phenomenon has received the designation GRB 090429B. The letters GRB are an abbreviation for the words gamma-ray burst - a burst of gamma radiation - as astronomers designate 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.
"Probably, it was a huge star, with a mass of 30 times more than our Sun," - said the leader of the research team, Dr. Antonino Cucchiara of the University of California at Berkeley.
Image caption The Swift satellite is a joint project between NASA and ESA“While we do not have sufficient data to attribute this star to the so-called Population III stars, 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 flares 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 with other telescopes and determine the distance to the gamma-ray burst.
Launched in 2004, the Swift satellite has the ability to quickly, less than a minute, optical and X-ray identification of 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 radiation.
Race for antiquity
Astronomers are now competing in who will fix 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 aboard by American astronauts in 2009.
How does a gamma-ray burst (GB) occur?
NASA scientists studying images taken by the Hubble telescope have already observed galaxies that are about 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 evolved.
Particular attention is drawn to the stars of the first generation. These bright blue variables originated from molecular clouds that formed early on shortly after the Big Bang.
These huge pulsating stars had a very short and turbulent cycle of development - only a few million years, giving rise to heavy elements during their death.
Their harsh ultraviolet radiation led to the reionization of the surrounding nebulae, which consisted mainly of hydrogen, stripping electrons from atoms, which in turn generated that extremely rarefied intergalactic plasma that surrounds the current generation of stars in our galaxy.
GRB 090429B is unlikely to be one of the very first stars in the universe, says Dr. Kukkiara. It is likely that even before that there were several generations of stars, about which we still do not know anything.
British and Italian engineers took part in the creation of the Swift orbital telescope. On board is a British X-ray camera that captures 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 observed space object in the universe from us, astronomers have said. This object is a galaxy MACS0647-JD, which is located 13.3 billion light years from Earth.
The universe itself, according to scientists, is 13.7 billion years old, so the light from this galaxy that we can see today is its light from the very beginning of the formation of the cosmos.
Scientists observe object with NASA space telescopes Hubble and "Spitzer", as well as 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 the so-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:
“Lenses like this can magnify the light of an object so much that no human-made telescope can do it., - He speaks Marc Postman, an astronomer at the Space Telescope Science Institute in Baltimore. - Without such a magnification, one must make a titanic effort to see such a distant galaxy."
The new distant galaxy is very small, much smaller than our Milky Way. scientists said. This object, judging by the light that has come down to us, is very young, it came to us from an era when the Universe itself was at the earliest stage of its development. She was only 420 million years old, which is 3 percent of her current age.
A 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 MACS0647-JD eventually merged with other small galaxies to form a larger one.
Cosmic merger of galaxies
"This object is possibly one of the many building blocks of some larger galaxy, the researchers say. - Over the next 13 billion years, it could go through tens, 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 that held the title of the most distant observable galaxy was the galaxy SXDF-NB1006-2, which is located at a distance of 12.91 billion light years from Earth. This object was seen with telescopes Subaru and "Kek" in Hawaii.
Studying the most distant galaxies can show us objects billions of light-years away, but even with perfect technology, the space gap between the most distant galaxy and the Big Bang will remain huge.
When we peer into the Universe, we see light everywhere, at all distances that our telescopes can only see. But at some point we will run into limitations. One of them is superimposed by the cosmic structure that is forming in the Universe: we can only see stars, galaxies, etc., only if they emit light. Without it, our telescopes can't see anything. Another limitation when using forms of astronomy that are not limited to light is the limitation of how much of the universe has been available 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 CMB redshift in the range of 1000 when the largest redshift of any galaxy we've seen is 11?First, we must deal with what has been happening in our universe since the Big Bang.
The observable universe may stretch 46 billion light-years in all directions from our point of view, but there are certainly other parts of it that we cannot observe, and perhaps they are even infinite.
The whole set of what we know, see, observe and interact with is called the “observable Universe”. There are likely more regions of the universe beyond it, and over time we will be able to see more and more of these regions when light from distant objects finally reaches us after a cosmic journey of billions of years. We can see what we see (and more, not less) thanks 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.
Timeline of the history of the observable universe
What we see today is the result of these three factors, together with the original distribution of matter and energy, working 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, all we have to do is observe what it is today, measure all the parameters involved, 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, while difficult, are at least unambiguous. The output results in two equations, known as the Friedmann equations, and the problem of solving them is one that every student of cosmology faces directly. But we, frankly, managed to make some amazing measurements of the parameters of the Universe.
Looking towards the north pole of the Milky Way Galaxy, we can peer into the depths of space. Hundreds of thousands of galaxies are labeled in this image, and each pixel is a separate galaxy.
We know how fast it is expanding today. We know how dense matter is in any direction we look. We know how many structures are forming at all scales, from globular clusters to dwarf galaxies, from large galaxies to their groups, clusters and large-scale filamentary structures. We know how much normal matter, dark matter, dark energy, as well as 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 its rate of expansion at any point in its cosmic history.
Logarithmic plot of the size of the observable universe versus age
Today, our observable universe spans about 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 at us today, 13.8 billion years later. In principle, at this distance all the gravitational waves left over from cosmic inflation were generated - the state that preceded the Big Bang, set up the Universe and provided all the initial conditions.
The gravitational waves created by cosmic inflation are the oldest signal of all that mankind could, in principle, 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 in the Universe. When it was 380,000 years old, the residual radiation from the Big Bang stopped scattering free charged particles as they formed neutral atoms. And these photons, after the formation of atoms, continue to experience redshift along with the expansion of the Universe, and they can be seen today with a microwave or radio antenna / telescope. But due to the rapid expansion of the Universe in its 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 where the universe was 380,000 years later is 900 million light years!
The cold fluctuations (blue) in the CMB are not colder per se, but simply represent areas of increased gravitational pull due to increased matter density. The hot (red) regions are hotter because the radiation in these regions lives in a shallower gravity 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 of all the galaxies in the Universe we have discovered. Although simulations and calculations show that the very first stars could form in 50-100 million years from the beginning of the Universe, and the first galaxies in 200 million years, we have not yet looked that far back (although, it is hoped 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 - that's just 3% of its current age. However, this galaxy, GN-z11, is only 32 billion light-years away, about 14 billion light-years from the "edge" of the observable universe.
The most distant of all the discovered galaxies: GN-z11, photo from the GOODS-N observation made by the Hubble telescope.
The reason for this is that at the beginning, the rate of expansion dropped very rapidly over time. By the time the galaxy Gz-11 existed as we observed 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 1036 times faster, or 1,000,000,000,000,000,000,000,000,000,000,000,000 times faster than today. Over time, the rate of expansion of the universe has greatly decreased.
And for us it is very good! The balance between the primary rate of expansion and the total amount of energy in the universe in all its forms is perfectly maintained, up to the error of our observations. If the universe had had even a little more matter or radiation in its early stages, it would have collapsed back billions of years ago and we wouldn't be here. If there had been too little matter or radiation in the universe early on, it would have expanded so rapidly 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 humans. . The cosmic story that the Universe tells us is the story of the extraordinary balance by which we exist.
The intricate balance between the rate of expansion and the overall density of the universe is so delicate that even a 0.00000000001% deviation in either direction would make 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 old. This corresponds to a distance from us to them of 35-37 billion light years, and a distance from the farthest galaxy to the edge of the observable universe of 9-11 billion light years today. This is extremely far, and speaks to one surprising fact: the universe expanded extremely rapidly 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 happened, the rate of expansion has plummeted, and is slowing down as the 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: the 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 current age, the distances will have increased so much that we will no longer be able to see any galaxies except for members of our local group, even with a telescope equivalent to Hubble. Enjoy all that is visible today, the great variety of what is present on all cosmic scales. It won't last forever!
The Hubble Orbital Telescope, launched in 1990, has become the main instrument of earthlings, pushing 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 you can really 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 the laws known to us for a long time.
The "edge" visible today contains objects that emitted light only hundreds of millions of years after the Big Bang. In that era, 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
Universal ruler Redshift is the ratio of the magnitude of the shift of the spectral line to the long wavelength side, to the wavelength in the laboratory frame of reference.
For objects that emitted light at the dawn of the birth of the Universe, this shift is many times greater than the wavelength itself
The Universe is constantly expanding, and the farther an object observed on a large scale, the faster it moves away from us. Therefore, the most convenient measure of distance is the assessment of the reddening of an object caused by the Doppler effect. Until recently, the most distant galaxy corresponded to the redshift 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. UDFj-39546284 was spotted in 2009, just three months after the Hubble telescope was a wide-angle camera UDFj-39546284 is installed. The faint speck seen in the deep sky view is nothing more than a compact galaxy made up 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 could be found,” said Richard Bowens.
Manger of the UniverseThe galaxy whose light has 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, in the observed era, the young Universe experienced 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 pace at which stars were born tells us that if we look a little further, 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 at Santa Cruz.
Beyond the edgeHaving passed the line at z=10, the astronomers approached the “edge of the edge”. The first 500 million years (at z from 1000 to 10) after the Big Bang remain a white spot in the currently accepted hierarchical model of galaxy formation - from star clusters to elliptical and spiral galaxies. The galaxy UDFj-39546284 was discovered in the farthest infrared range that the instruments of the Hubble telescope can observe. To look further into the very early years of the universe, scientists hope with the help of the James Webb telescope.