Astronomers “discovered” in another galaxy.
The first discovery of a planet located outside the Solar System was a real scientific achievement. The first discovered exoplanets were discovered with the help of ground-based observatories, so at first their number was small. But with the launch of new, more powerful space telescopes, such as Kepler, the number of open worlds began to skyrocket. By February this year, scientists had confirmed the discovery of 3,728 exoplanets located in 2,794 systems, 622 of which 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 found evidence of planets in a galaxy located about 3.8 billion light-years away.
A paper describing the details of the discovery, titled “Probing Other Galaxies using Quasar Microlensing,” was recently published in the Astrophysical Journal Letters. The study was led by PhD Candidate Xinyu Dai and Professor Eduardo Guerras from the Department of Physics and Astronomy at the University of Oklahoma.
For their research, astrophysicists used the method of gravitational microlensing, where the lens is some massive astronomical object like a star, which, with the help of its gravitational fields, changes the direction and focuses the propagation of electromagnetic radiation, just as an ordinary lens changes the direction of a light beam. Gravitational microlensing is a scaled-down method of gravitational lensing. In the latter, the lens is already much larger objects like galaxies or even clusters of galaxies, which change the direction of light of the observed object located behind the lens. Both options are used in the transit method of detecting planets. When a planet passes by a star relative to an observer (that is, it transits), the star’s light changes accordingly, and thus scientists can determine the presence of a planet.
In addition to the microlensing method, which allows us 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 Chandra Space X-ray Observatory to study the quasar RX J1131-1231. First of all, scientists were interested in the microlensing properties of a supermassive black hole located next to this quasar.
In addition, to calculate the microlensing models used, the scientists also used the computing power of a supercomputer. As part of the data analysis, the researchers found energy shifts that could be explained by the presence of approximately 2,000 unrelated planets located between the quasar and the Earth, with masses ranging from the mass of the Moon to Jupiter.
Image of the gravitational lens of the galaxy RX J1131-1231 with a lenticular galaxy in the center and four quasar images in the background. The researchers suggest that in this image, there are trillions of planets at the center of the elliptical galaxy.
“We are very happy about this discovery. For the first time, planets have been discovered outside our galaxy. It is the presence of planets that can best explain the signatures that we observed in the study using the microlensing method. Using data modeling and analysis of the high frequencies of these signatures, we tried to find out the mass of their sources, ” Xinyu Dai commented in a published press release.
Using the microlensing method, scientists have already discovered 53 planets inside the Milky Way, but this is the first time that astronomers have been able to detect signs of planets in other galaxies. As in the case of exoplanets located outside the Solar system, scientists up to this point were not sure that planets can be found in other galaxies. This discovery takes the exploration of space beyond the Solar System to a truly new level.
Eduardo Guerras notes that the discovery was made possible by the significant development in recent years of both modeling methods 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 away, and we have no way of observing these planets directly. Even our best telescopes can’t do that. This can only be imagined in science fiction. Nevertheless, we are really able to study them, confirming not only their existence, but even assuming their masses.”
In the coming years, several new and state-of-the-art observatories are expected to open and operate at once, which will allow even more amazing discoveries to be made. The James Webb Space Telescope, the European Extremely Large Telescope, and the Colossus Telescope are just a few of the names on the list.