Behind the dense gas clouds of the Milky Way Center there could be a previously unknown galaxy. Picture: Nasa
Read aloud American researchers suspect behind the center of the Milky Way a twin of our galaxy. This twin galaxy could hide behind dense gas clouds blocking the view beyond the Milky Way Center, speculate astronomers Avi Loeb and Ramesh Narayan of the Harvard-Smithsonian Center for Astrophysics in Cambridge, USA. A twin galaxy similar in size to the Milky Way and three million light-years away could perform a sufficient gravitational pull to explain the motion of our galaxy. The researchers calculated the movement of our Milky Way towards the so-called cosmic background radiation. This radiation is to a certain extent the reverberation of the Big Bang, hits the Milky Way evenly from all sides and allows the exact determination of the Milky Way movement. In addition, the researchers calculated how strongly galaxies with distances of up to 400 million light-years affect the movement of the Milky Way.

But the known galaxies in the area can not quite explain the direction and speed of the Milky Way movement, the researchers realized. Therefore, they assumed that there could be another galaxy or even entire galaxy systems in the hidden area behind the center of the Milky Way galaxy. The researchers therefore calculated the mass and distance of these hypothetical star systems in order to reconcile the Milky Way movement on the basis of the galaxy distribution and the background radiation.

According to the calculations, behind the center of the Milky Way galaxy could be a similarly large galaxy only three million light-years away. Alternatively galaxy clusters in 70 million light-years distance would be conceivable. However, other astronomers such as Brent Tully of the University of Hawaii in Honolulu believe that a twin system to explain the Milky Way movement is not necessary. Far beyond the galaxies considered by the researchers Loeb and Narayan, there are still large galaxy clusters, such as the Shapley supercluster 650 million light-years away, which also attract the Milky Way. If there were star systems just beyond the Milky Way, astronomers would have discovered them long ago, Tully says.

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