The first discovery of a planet outside the solar system has become a real scientific achievement. The first open exoplanets were discovered using ground-based observatories, so at first their number was few. But with the launch of new, more powerful space telescopes, such as Kepler, the number of open worlds began to grow rapidly. By February this year, scientists confirmed the discovery of 3,728 exoplanets located in 2,794 systems, of which 622 have more than one planet.
More recently, astronomers have reported a new achievement. Astrophysicists from the University of Oklahoma (USA) for the first time in history conducted observations of planets located in another galaxy. Using the predictive method described in Einstein's general theory of relativity, a team of scientists discovered evidence of planets in a galaxy about 3.8 billion light-years away from us.
An article describing the details of the discovery and called "Probing other galaxies using the quasar microlensing ", was recently published in the journal Astrophysical Journal Letters. The research supervisors were Candidate of Sciences Sinu Dai and Professor Eduardo Gerras from the Department of Physics and Astronomy of the University of Oklahoma.
A method of gravitational microlensing was used to study astrophysics, where a massive astronomical object like a star appears as a lens, using its gravitational fields changes the direction and focuses the propagation of electromagnetic radiation, just as a conventional lens changes the direction of the light beam. Gravitational microlensing is reduced in scale by the method of gravitational lensing. In the latter, lenses are already much larger objects like galaxies or even clusters of galaxies that change the direction of light of the observed object behind the lens. Both variants are used in the transit method for detecting planets. When the planet passes by the star relative to the observer (that is, it transits), the light of the star changes accordingly, and thus scientists can determine the presence of the planet.
In addition to the microlensing method, which allows to determine the presence of objects located only at really very large distances from us (we are talking about billions of light years), the researchers used data from the space X-ray observatory Chandra to study the quasar RX J1131-1231. First of all, scientists were interested in the microlensing properties of a supermassive black hole located near this quasar.
In addition, to calculate the microlensing models used, scientists also used the computing power of a supercomputer. In the data analysis, the researchers found energy shifts that could be explained by the presence of approximately 2000 unconnected planets located between the quasar and the Earth, with masses varying from the mass of the moon and to Jupiter.
The image of the gravitational lens of the galaxy RX J1131-1231 with lenticular galaxy in the center and four images of the quasar, located on the background. The researchers suggest that in this image in the center of the elliptical galaxy are trillions of planets
"We are very pleased with this discovery. For the first time, the planets were discovered outside of our galaxy. It is the presence of planets that can best explain the signatures that we observed in the study using the microlensing method. With the help of data modeling and high-frequency analysis of these signatures, we tried to find out a lot of their sources, "commented Sinyu Dai in a published press release.
With the microlensing method, scientists have already discovered 53 planets within the Milky Way, when astronomers managed to detect signs of the presence of planets in other galaxies. As in the case of exoplanets that are located outside the solar system, scientists until now were not sure that planets can be found in other galaxies. This discovery brings the study of space beyond the solar system to a truly new level.
Eduardo Gerras notes that the discovery was made possible through the significant development in recent years of both modeling techniques and hardware.
"This is an example of how effective our methods of analyzing extragalactic microlensing data can be. This galaxy is located about 3.8 billion light-years from us, and we do not have any possibility to observe these planets directly. Even the best of our telescopes are not capable of this. This can only be imagined in science fiction. Nevertheless, we are really able to conduct their study, confirming not only their existence, but even assuming their masses. "
In the coming years, several new and most modern observatories should open and earn at once, which will make even more amazing discoveries. Space Telescope James Webb, European extremely large telescope, Colossus telescope – these are just a few names from the list.