The general theory of relativity, formulated by Albert Einstein more than a century ago, has now been shown to work also in galaxies beyond the Milky Way, the European Southern Observatory (ESO) reported in a statement.
An international team of astronomers has combined data from the NASA Hubble Space Telescope with ESL’s Very Large Telescope in Chile and their results show that gravity behaves as predicted by Einstein in his Theory of General Relativity on a galactic scale .
The ESO 325-G004 galaxy was used for the study, which acts as a strong gravitational lens, distorting light coming from a distant galaxy behind it and creating an Einstein ring around its center.
Comparing the mass of ESO 325-G004 with the curvature of space around it, astronomers discovered that gravity at these scales of astronomical distances behaves as predicted by general relativity, which “rules out some alternative theories of gravity” , indicates the note.
Data from Chile’s Very Large Telescope (VLT) were used to measure how fast the ESO 325-G004 stars moved, which allowed scientists to infer how much mass there must be in the galaxy to keep the stars in orbit.
In addition, Hubble has observed an Einstein ring resulting from the distortion exerted by ESO 325-G004 in light from a distant galaxy.
“Observing the ring, the astronomers could measure how light (and, therefore, spacetime), are diverted by the enormous mass of ESO 325-G004,” the note details.
Einstein’s theory of general relativity predicts that objects deform space-time around them, causing any light that passes close to be deflected.
The study director Thomas Collet of the British University of Porstmouth indicated that thanks to the data of the VLT and Hubble, the force of gravity was measured in two different ways.
The result, he explained, “is just what general relativity predicts with an uncertainty of only nine percent.” This is the most accurate test of general relativity outside the Milky Way done to date, and using only one galaxy!”
General relativity has been put to the test with “exquisite precision” at scales of the Solar System before. However, such precise tests had not been made at larger astronomical scales. Testing the long-range properties of gravity is of vital importance to validate the current cosmological model.
These findings, the statement said, may have important implications for alternative gravity models to general relativity, which predict that the effects of gravity on the space-time curvature “depend on the scale”.
Thus, gravity should behave differently at the scale of great astronomical distances with respect to the smallest scales of the Solar System.
However, Collett and his team have discovered that this is unlikely to be the case, unless these differences only occur at scale distances of more than 6,000 light years.
Professor Bob Nichol, from the University of Porstmouth and a member of the team, said, on the other hand, “it is very satisfying to use the best telescopes in the world with the aim of challenging Einstein and finding out, in the end, how right he was”.