Astronomers have decided to test the applicability of the general theory of relativity in one of the most exotic corners of the universe. In conditions of extreme gravity theory has withstood the centenary.
Astronomers were able to test the applicability of the general theory of relativity in such extreme conditions, which did not create the world, and the universe is not easy to find. Such a laboratory for them has become a very exotic object – a binary system consisting of a massive neutron star spinning wildly around the white dwarf.
neutron star PSR J0348 +0432 is the remnant of a supernova explosion. It is twice as heavy as the Sun, although spans a total of 20 kilometers.
The force of gravity on the surface of more than 300 billion times greater than the force of gravity, and the substance in its center is compressed to a density such that the volume of a cube with a piece of sugar weighs more than a billion tons.
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Her companion white dwarf – a dim it much easier to balance the star, which in the past threw the atmosphere and slowly cools down.
applicability of the general theory of relativity has been repeatedly tested beyond Earth, but if it works in a super strong gravity, such as those present in the vicinity of massive neutron stars, was a mystery. At the moment, theorists developed several alternative theories of gravity, which differ from the predictions of general relativity could occur only in extremely strong gravitational fields.
That is why an international team of scientists led by John Antoniadis of the Institute for Radio Astronomy, the Max Planck in Bonn for testing general relativity has chosen a unique system of PSR J0348 +0432. The neutron star at the center of this pair is a pulsar: Because of its magnetization it sends into space strictly periodic signals that the world record by radio telescopes. According to the predictions of general relativity, such a massive and close system, emitting gravitational waves must gradually lose energy: the white dwarf must be close to a neutron star and spinning faster and faster.
These evolutionary changes and predicted a different theory of General Relativity and competing theories of gravity.
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Observations made on several ground-based radio telescopes revealed a slowdown in pairs, and the general theory of relativity has resisted. “Our radio observations were so accurate that we were able to measure the deceleration of the orbital period in 8 millionths of a second in a year, exactly as predicted by Einstein’s theory,” – said Paulo Freire, one of the co-authors of a paper published in the journal Science .
about the details of their participation in the verification of predictions of Einstein “Gazeta.ru” said a direct participant in this work, a research fellow at the Netherlands Institute for Radio Astronomy, Vladislav Kondratiev.
– How would you have formulated the main conclusion of this article? It lies in the fact that numerous studies on different telescopes possible to measure the change of the orbital period (and there accuracy – millionths of a second), and the obtained value with the accuracy coincided with the predictions of general relativity? That is another “Eyshnteyn was right»?
– Yes, that’s right. First, it is worth noting that the mass of the pulsar is about two solar masses. Such massive neutron stars can further restrict the set of possible equations of state of neutron star (mass dependence of the radius), that is closer to an understanding of the behavior of neutron matter inside the star.
While this is only the second massive (with a mass of about two solar masses), a neutron star with a very well-defined mass (accuracy – 2%). But the main thing, of course, is that unlike other binary systems with our double pulsar system is very compact. This makes the system a relativistic, in which the effects of general relativity or other alternative theories should exhibit much stronger. And the resulting reduction of the measurement of the orbital period due to the emission of gravitational waves in a strong gravitational field have shown that general relativity is correct within the error.
– What was your participation in this study?
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– I was directly involved in the view of the sky in search of pulsar radio telescope in Green Bank in 2007, conducting surveillance and making post-processing of data, along with my other colleagues. In this review (GBT 350 MHz Drift-Scan survey) we have found 31 new pulsars, including 7 millisecond, and the results were published late last year in two studies. One of these millisecond pulsars was J0348, a binary pulsar and a low-mass white dwarf. In subsequent regular timing observations of radio and optical observations with the VLT and Apache I did not participate, but, of course, along with other colleagues discussed the results, preparing the publication.
– you are a member of the project ASTRON. Can you tell me more about it?
– ASTRON – the official name of the Institute for Radio Astronomy in Holland (Netherlands Institute for Radio Astronomy, ASTRON, www.astron.nl). Since 2009 I work there researcher in astronomy group engaged in the study of pulsars. ASTRON got its name in the late 80′s, and before that was originally called SRZM and directly involved in the design and management of telescopes. ASTRON and is now one of the leaders in the development and design of new tools for astronomy. Until recently (10-15 years), astronomers directly in the state was a little bit, but with the development of the project LOFAR (Low-Frequency Array) astronomical group increased significantly (about 30 people – staff, researchers, students). WSRT and LOFAR telescopes are operated by ASTRON.
– How can you compare the conditions for doing science in Russia and in the Netherlands?
– Objectively, I can not compare the situation in the Netherlands with the current situation in Russia, because it does not work in Russia for several years, although, of course, communication support, but do not know the current situation from the inside. But, based on past experience, compliance with wage students, graduate students, researchers believe the normal standard of living is very important. All things being equal in the material sense, if the science is interesting, the greater the likelihood that a student would go to graduate school. The second important point which may in some way connected with the first, is that science in Russia (speaking of “science”, I mean more specifically astronomy and radio astronomy, I do not know the situation well in other areas) revolves largely in its own juice. Extensive cooperation with other groups in the world of small, sparse attendance at conferences. Even in the case where there is a mutual desire to take a foreigner to work in, say, as a postdoc, it in fact turns out to be impossible because of the paper bureaucracy.
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