A team of astrophysicists from the University of Oklahoma (USA) has discovered for the first time in history a population of planets beyond the Milky Way using microlenses . Thanks to this astronomical phenomenon, they were able to detect objects in extragalactic galaxies ranging from the mass of the Moon to the mass of other large planets such as Jupiter.
Given how difficult it is to find exoplanets even within our Milky Way, this is a major milestone that researchers have achieved thanks to the clever use of gravitational microlenses.
The technique, first predicted by Albert Einstein’s theory of general relativity, has been used to find exoplanets within the Milky Way, and is the only known way to find the smallest and most distant planets, which are thousands of years away. light of the Earth.
So far, 53 exoplanets have been detected within the Milky Way with this method. However, until this study, there had been no evidence of planets in other galaxies.
For this study, researchers Xinyu Dai and Eduardo Guerras used NASA’s Chandra X-ray Observatory at the Smithsonian Astrophysical Observatory. They studied a quasar 6 billion light-years away called RX J1131-1231 , one of the best gravitational lensing quasars in the sky, finding that there were peculiar energy shifts in the quasar’s light that could only be explained by planets. of the galaxy that project the quasar.
After calculating the microlensing models at the University of Oklahoma Supercomputing Center for Education and Research, it turned out that these signatures corresponded to around 2,000 planets with masses ranging from that of our Moon to Jupiter, among the stars of the galaxy. .
“This is the first time that someone has discovered planets outside of our galaxy. These small planets are the best candidate for the signature that we observed in this study using the microlensing technique. We analyzed the high frequency of the signature by modeling the data to determine mass. We are very excited about this discovery, “says Dai.
“Of course, we have not seen the planets directly, and it is unlikely that there is life there, but being able to detect them is an incredible testament to the power of microlensing, not to mention the evidence that there are planets in other galaxies,” continues the astrophysicist.
Logically our common sense tells us that there must be a very important range of planets out there, but having the scientific evidence that this is the case is going one step further.
“This is an example of how powerful extragalactic microlensing techniques can be,” said Guerras.
The galaxy in question is 3.8 billion light-years away, and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine. “However, we can study them, reveal their presence and even have an idea of their masses,” says Guerras.
Reference: Xinyu Dai, Eduardo Guerras. Probing Planets in Extragalactic Galaxies Using Quasar Microlensing . The Astrophysical Journal , 2018; 853 (2): L27 DOI: 10.3847 / 2041-8213 / aaa5fb
Image credit: Oklahom University
