General relativity in a radical binary star system consisting of two pulsars maintains a series of precision experiments.
In 16 years of experimentation, a team of international researchers from ten countries has tested Einstein’s general theory of relativity through rigorous experiments to date. The team, led by Michael Kramer of the Max Planck Institute for Radio Astronomy in Panel, studied two unique pairs of stars with extreme properties called two pulsars orbiting each other in a binary star system. Seven radio telescopes around the world were involved in the measurements. In the process, new relativistic effects appeared, which, although expected, were now seen for the first time. Einstein’s general theory of relativity agrees more than 99.99 percent with observations.
More than 100 years after Albert Einstein published his theory of gravity, scientists around the world have been constantly trying to point out the limits of general relativity. It would be an important finding to note any deviations from the predictions of this theory. This will open the window to new physics and go beyond our current theoretical understanding of the universe.
“We studied a two-star system with a very high density, which is a unique laboratory to test Einstein’s predictions in the presence of very strong gravitational fields,” said Michael Kramer, director of the Max Planck Institute for Radio Astronomy at Panel. “To our delight, we were able to measure the cornerstone of the general theory of relativity, that is, the energy radiation of gravitational waves, with 1000 times more accuracy than is currently possible by detectors on Earth.”
According to Kramer, the observations not only show better agreement with the theory, but also show previously unattainable consequences. Ingrid Stars of the University of British Columbia in Vancouver gives an example: “We followed the propagation of radio photons from Pulsar and studied their motion in the strong gravitational field of Pulsar associated with it.”
The researchers were the first to find that light was not only delayed but also deflected by a small angle of 0.04 degrees due to the strong curvature of space-time around the fellow. “Such a test has never been done before with such a strong space-time curve,” says Stairs.
Called the “Double Pulsar”, the cosmic laboratory was discovered in 2003 by team members. It consists of two pulsars – high-density burned star bodies that rotate rapidly on their axis and emit radioactivity in action. When the radiation cone of such a neutron star sweeps the Earth, it looks like a cosmic lighthouse and its radiation “beats”. Hence the name Pulsar.
The two pulsars orbit each other at a speed of one million kilometers per hour in just 147 minutes. A pulsar spins very fast 44 times per second. The sub is young and has a cycle duration of 2.8 seconds. The motion of two stars around each other can be used as an almost perfect laboratory for studying theories of gravity in extreme contexts.
Each of the pulsars is about 30 percent larger than our sun, but only 15 miles in diameter. “If objects like this move around each other so quickly, we can test seven predictions of general relativity,” says Dick Manchester of CSIRO, the National Science Institute in Australia. Thanks to the accuracy of the experiment, among other things, it was possible to measure the effect of the so-called time extension, which slows the clocks in gravitational fields.
“We have to use Einstein’s popular equation E = mc2 When examining the impact of electromagnetic radiation from a fast-rotating pulsar into orbit, ”says Manchester. “This radiation is equivalent to a mass loss of eight million tons per second.” It sounds like a lot, but it’s only a small fraction – three-quarters of a billionth of the total mass of Pulsar.
In addition, researchers have been able to demonstrate with precision a fraction of a million that the orbit changes its orientation. This is a relative effect known from Mercury’s orbit, but here it occurs 140,000 times more than the inner planet in our solar system. With this accuracy, the panel recognized that the effects of the pulsar’s rotation on the surrounding space-time must also be taken into account, as it pulls with the rotating pulsar.
This phenomenon is called lens tying effect or frame tracking. “In our experiment, the inner structure of the pulsar should look like a neutron star,” says Norbert Wex of the Max Planck Institute in Panel, another author of the study. Measurements made it possible for the first time to use a technique called pulsar timing to obtain accurate reports of the magnitude of a neutron star by accurately monitoring its rotation.
The process of pulsar time is determined by high-resolution imaging of its distance in conjunction with careful interferometric measurements of the pulsar system. The result is 2400 light years, with only eight percent error. According to Adam Teller of Swinburne University in Australia, the combination of different, complementary tracking techniques creates the value of the experiment. In addition to the aforementioned pulsar timing and interferometry, data on the effects of galaxy media were also taken into account.
“Our results are a good addition to other experimental experiments that test the force of gravity under different conditions or detect gravitational wave detection or various effects such as the phenomenon Horizon telescope,” says Palo Fryer from the Max Planck Institute of Radio Astronomy.
In the words of Michael Kramer, the measurements reached “unprecedented levels of accuracy.” The work shows how exactly such tests were carried out and what subtle effects should be taken into account. “Maybe one day we will actually see a departure from general relativity.”
NJ / HOR
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