Stellar orbital precession S2 fully coincides with general relativity, and Einstein wins again |

The S2 star that orbits the supermassive black hole Sagittarius A * in the center of the Milky Way is the astronomers’ favorite research object to verify Einstein; After nearly 30 years of monitoring, a new study found that the S2 star’s orbit has changed slightly, and Einstein’s sport and theories fit perfectly.

In the center of the Milky Way galaxy, hundreds of stars orbit around the supermassive black hole Sagittarius A *. For decades, scientists have been tracking the movement of stars. This is one of the best places to test Einstein’s general theory of relativity. Among them, the S2 star closest to a black hole is the most special, with an orbital period of approximately 16 years.

If according to Newton’s description of the gravitational field, the star S2 should travel in an elliptical orbit, and each cycle should follow exactly the same path as the previous orbit. However, modern data analysis shows that this is not the case. In contrast, the orbits of S2 stars change over time, as predicted by general relativity.

A team of researchers analyzed the 27-year-old S2 star data observed by the Very Large Telescope and confirmed for the first time that the star appeared in the Schwarzschild precession; Just like shaking the hula hoop, the path cannot stay on the same plane forever, but scrolling up and down is possible. This type of precession was first observed in Mercury’s orbit in orbit around the sun about a century ago, and new research now shows that even in the most extreme gravity environment, Einstein’s theory still holds.

▲ Schwarzschild’s precession of the S2 star.

Furthermore, the general relativity equation can also accurately predict orbital change, and the result of the calculation also precisely matches the actual observation value of S2.

This new article is not the first to use S2 stars to check general relativity. Astronomers have been observing this star closely since the 1990s. In 2018, research by the Max-Planck-Institut für extraterrestrische Physik (MPE) team confirmed that the S2 star is approaching Sagittarius’ red-shift data. A * are inconsistent with Newton’s prediction, but are completely consistent with the prediction of general relativity. The following year, another group of independent studies also confirmed these results.

Now, the Max Planck Institute for Extraterrestrial Physics continues to use observational data from 1992 to the end of 2019 for more than 300 measurements. The purpose is to detect whether the star also has a Schwarzschild precession as predicted by general relativity, and the result also shows that Ein Stan was successful again.

Astrophysicists Guy Perrin, Karine Perraut and others said that because the S2 star perfectly follows the prediction of general relativity, it means that we will be able to carry out how much invisible matter (such as dark matter or possibly small black holes) around Sagittarius A *. Strict constraints allow us to better understand the formation and evolution of supermassive black holes.

The new article was published in “Astronomy & Astrophysics” (Astronomy and Astrophysics).

(Source of the first image: European Southern Observatory)

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