Researchers from the Weizmann Institute assisted in confirming the data
See another news on the subject: For the first time, gravitational waves and light waves were discovered from the same event - the merger of two neutron stars
An international research team was recently able to observe, for the first time, the collision and merger of two neutron stars. Many scientists from different countries in the world, including scientists from the Weizmann Institute, managed to analyze the collision data. The merger was discovered at the same time by three detectors that were built especially for this purpose: two in the USA, calledLego", and one, called "Virgo", operating in Italy. The observation will deepen the understanding of events of this type, which are considered the most violent in the universe. Among other things, the observation may help to understand the way in which uranium, iodine, gold and other heavy elements were formed.
The discovery of the neutron star merger was observed on August 17, and after completing the data analysis, the scientists published their findings in the scientific journals Astrophysical Journal, Nature, Science, and in other leading journals.
About two years ago, the "LIGO" detectors already made another sensational discovery: they allowed scientists to observe gravitational waves for the first time. These waves, whose existence was predicted by Albert Einstein, were created by the collision of two huge black holes, and took more than a billion years to reach the Earth. Following this discovery, it was announced at the beginning of October that the 2017 Nobel Prize in Physics would be awarded for "a decisive contribution to the construction of the LIGO detector and the observation of gravitational waves".
Our findings indicate, among other things, that every atom of iodine on Earth, including the iodine we use to disinfect wounds, came in the distant past from the merger of neutron stars."
The merger between the two neutron stars took place in the relatively "recent" past: "only" about a hundred million years ago. But especially important is the fact that this merger provided scientists with more information than the merger between the black holes. "When two black holes collide, all that can be detected are gravitational waves, because everything else is swallowed in," saysProf. Avishai Gal-Yam From the Department of Particle Physics and Astrophysics at the Weizmann Institute of Science. "On the other hand, neutron stars 'weigh' less than black holes. Therefore, when they collide and merge, part of the radiation and mass is emitted - and then they can be detected, at the same time as the gravitational waves."
Gravitational waves are sensed by the detector for only a fraction of a second, but the rest of the radiation from the merger of the neutron stars arrives over several days. This radiation came in more familiar forms, including X-rays ("x-rays"), gamma radiation, as well as radiation in the ultraviolet, infrared, and visible light wavelengths. "Many telescopes noticed this radiation, which appeared as a new point in the sky, but at first we were not sure that this point was really the merger of the stars discovered by the detectors "Ligo" and "Virgo", says Prof. Eran Ofek, also from the Department of Particle Physics and Astrophysics at the Weizmann Institute of Science.
Researchers around the world, including Prof. Ofek's group, deciphered the information about the merger and came to the conclusion that the spot was indeed the "optical signature" of the neutron star merger that the detectors discovered. Prof. Ofek and other scientists determined that the amount of material emitted was approximately one hundredth of the mass of the sun and that this material flew through space at a speed of about a quarter of the speed of light. "This is the first time that such a large amount of matter has been observed in such rapid motion," says Prof. Ofek.
This is the first time that such a large amount of matter has been observed in such rapid motion."
Prof. Gal-Yam and other scientists analyzed the radiation, and their findings provided evidence that the merger of the stars led to the formation of heavy elements. Much is known about the formation of light elements, but the origin of heavy elements has been a mystery until now. Because the nuclei of these elements contain many neutrons, one theory proposed that they originate from merging neutron stars: these stars are packed with neutrons, and their collision can cause fast collisions between neutrons, which may lead to the formation of heavy elements. "This theory has existed for at least 50 years, and only now, finally, can we strengthen the evidence that this is indeed what happened," says Prof. Gal-Yam. "Each element in nature absorbs and emits light in a different part of the spectrum, and thus, using a technology called spectroscopy, we were able to determine which elements emitted the radiation observed following the merger of the stars."
The scientists were able to identify relatively rare heavy elements, such as tellurium, but also more common ones, such as cesium and iodine. "Our findings indicate, among other things, that every atom of iodine on Earth, including the iodine we use to disinfect wounds, arrived in the distant past from the merger of neutron stars," says Prof. Gal-Yam. He adds that the origins of heavier elements such as uranium and gold may also be in neutron star mergers, but for reasons that are not clear at the moment, these elements have not been identified in the current merger.
Prof. Ofek and Prof. Gal-Yam are part of extensive international scientific collaborations that have dealt with deciphering data from neutron star mergers. The results of these analyzes may later lead to further discoveries about the origins of heavy elements, and provide answers to open questions about the nature of gravity, and the explosions in which stars "die".
See more on the subject on the science website:
- Einstein - the man who started to take us out of the matrix: there are gravitational waves!
- Nobel Prize in Physics for the discovery of gravitational waves
- "The winners of the Nobel Prize in Physics were themselves surprised by the strength of the signal of the first gravitational wave event"
- A collaboration between three observatories resulted in another discovery of gravitational waves
- A new detector will determine the origin of gravitational waves
- A third gravitational wave event has been discovered; Confirms the existence of a new type of black holes
- Proof of Einstein's theory of general relativity: "The discovery of gravitational waves opens a new window to the universe"
