China fully commissioned the world's largest radio telescope

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China fully commissioned the world's largest radio telescope
China fully commissioned the world's largest radio telescope
Anonim

The PRC has finally commissioned the world's largest and most sensitive single radio telescope. He promises to reveal many secrets of the universe.

The birth of a giant

This is the FAST tool. This is an abbreviation of the phrase Five hundred meter Aperture Spherical Telescope, that is, "Spherical radio telescope with a five hundred meter aperture." This is a huge "plate" 500 meters in diameter, located in a natural karst depression.

FAST holds a world record in area, overtaking such large-scale instruments as the American Arecibo (300 meters in diameter) and the Russian BSA (200 400 meters in diameter). And since the sensitivity of a radio telescope is directly proportional to its area, FAST is also the most sensitive in the world. In other words, it is capable of detecting extremely dim objects.

At the same time, FAST receives radiation in a huge wavelength range: from 10 centimeters to 4.3 meters. Thus, it covers a significant part of the range of radio waves transmitted by the earth's atmosphere: from fractions of a millimeter to the first tens of meters.

The telescope mirror consists of 4,500 individual cells. This structure allows you to finely adjust its shape, compensating for various deformations.

The construction of the facility began in 2011. Test observations have been carried out since 2016. And a few days ago, the telescope was finally put into operation. According to Xinhua news agency, all technical indicators of the telescope have reached or exceeded the planned level.

According to the Universe Today publication, in 2020-2024 FAST will review the entire sky area available to it. Numerous quasars, radio galaxies, neutron stars, cosmic masers and so on will fall into his field of view.

In this case, half of the telescope observation time will be spent on the survey, and the other half will be allocated for other tasks. Let's tell you more about them.

Maps of matter in the universe

Almost 80% of the atomic nuclei in the Universe are in the intergalactic gas, another 10% - in the interstellar gas. That is, the task of making a map of the distribution of atoms in the Universe is basically reduced to mapping the intergalactic gas. The latter is 75% hydrogen and 23% helium well mixed with it.

Fortunately for astronomers, hydrogen atoms emit radio waves 21 centimeters long. Therefore, extreme sensitivity will allow FAST to build large-scale maps of the distribution of matter in a large part of the observed space.

Such information will allow checking the expansion models of the Universe and the theory of gravity, clarifying the concept of dark energy, and possibly even finding additional dimensions.

FAST will build more detailed maps for the Local Group of Galaxies. Among other things, this will allow us to test our ideas about the nature of dark matter.

Let us explain. It is believed that it is dark matter that has gathered under the influence of its own gravity in the embryos of modern galaxies. Its attraction accumulated gas around these clumps, from which stars were subsequently formed.

This is where the problem lies. According to the model of cold dark matter (the most popular among specialists), several thousand galaxies should have formed in the Local Group. Only about twenty are observed. Where are the others?

There is a hypothesis that everything else is dark galaxies. This is the name of hypothetical galaxies in which stars do not form at all due to the too low density of matter. Such systems consist only of dark matter and gas attracted by its gravity, mainly hydrogen.

So far, dark galaxies are only the fruit of theoretical constructions. Found only a few systems extremely poor in stars. However, the FAST sensitivity should be sufficient to detect legions of these ghost galaxies in the Local Group. Just a few minutes of signal accumulation will be enough to find a cloud of atomic hydrogen with a mass of ten thousand suns.

If observations show that there are no dark galaxies in the Local Group in the required quantity, scientists will have to reconsider their ideas about the nature of dark matter.

Image
Image

The giant telescope mirror is set in a natural karst depression.

Photo by EPA.

Space beacons

FAST is expected to help discover many radio pulsars. "Vesti. Nauka" (nauka.vesti.ru) told about them in detail. Recall that these are neutron stars that emit radio waves in a narrow beam.

According to theoretical estimates, there are about a billion neutron stars in the Galaxy, including up to 200,000 active pulsars. At the same time, observers are still aware of only about three thousand of these amazing objects.

Even in the test observation mode, which FAST has been in since 2016, he helped discover 102 new pulsars. This is more than all research teams from Europe and the United States found on all instruments over the same period.

Experts believe that a year of full-fledged operation will be enough for the new telescope to discover about a thousand new neutron stars.

Lasers and molecules

Another intriguing class of objects of observation is space masers, that is, natural radio lasers. The mechanism of operation of masers in the Milky Way is more or less clear to specialists, although here too many details need to be clarified. But the extremely powerful megamasers that flash in the nuclei of other galaxies are practically Terra Incognita. Although these objects have been known for about 40 years, astronomers still do not know what processes are driving them.

Scientists hope FAST will help shed light on this mystery as well. In particular, it has a chance to become the first telescope to detect a methanol-based megamaser (so far, this molecule has manifested itself only in more modest masers).

By the way, about molecules. Spectral lines of 14 molecules fall within the range of the telescope. In particular, the tremendous sensitivity of the instrument will make it possible to search for complex organics in the Galaxy. Such observations should provide invaluable information about the exotic chemistry of the interstellar medium. It is in her, perhaps, that the key to the origin of life is hidden.

Together with the whole East

Finally, FAST can become the basis for a large-scale network of radio telescopes operating as a single instrument (radio interferometer). Such systems provide tremendous resolution (the ability to distinguish fine details). For example, it was such a network that allowed the long-awaited image of a black hole to be obtained in 2019.

Usually, in such a scheme, a large main telescope is highlighted, and the rest work as auxiliary elements. In this case, all the tools should be located, simply speaking, on one side of the globe.

In the case of "portraying" a black hole, the first violin was played by the ALMA instrument located in Chile. Therefore, only telescopes of the Western Hemisphere could be included in the network.

FAST may become the center of an interferometer that will integrate Chinese, Indian, Japanese and Russian radio telescopes. Instruments from Eastern Europe can also connect to it. The new large-scale interferometric system can also bring many amazing discoveries to mankind.

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