19 Apr. (EUROPE PRESS) –
It has been confirmed that the intrinsic alignments of galaxies have characteristics that allow them to be a powerful probe of dark matter and dark energy on a cosmological scale.
By collecting evidence that the distribution of galaxies more than tens of millions of light-years away is subject to the gravitational effects of dark matter, an international team with the participation of Kyoto University succeeded in proving the general theory of gravity at large spatial scales. He analyzed the positions and orientations of galaxies, acquired from archived data of 1.2 million galaxy observations.
With the help of available 3D position information for each galaxy, the resulting statistical analysis quantitatively characterized the degree to which the orientation of distant galaxies is aligned. The work is published in The Astrophysical Journal Letters.
“These alignments, which are mainly produced by interactions with nearby objects, have been considered as systematic noise in the measurement of weak lensing,” says lead author Atsushi Taruya of Kyoto University’s Yukawa Institute for Theoretical Physics.
“We have also successfully measured the rate at which the galaxy distribution gradually becomes denser due to gravity, which is consistent with the general theory of relativity”, says Teppei Okumura of the Academia Sinica’s Institute of Astronomy and Astrophysics.
“Our research verified general relativity in the distant universe, but the nature of dark energy or the origin of cosmic acceleration remains unresolved,” adds Okumura.
The archived data, obtained from the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey, consists of three galaxy samples selected for their brightness and distance. In addition, the 3D positions and shape information of each galaxy helped measure the magnitude of the alignment relative to distant galaxies.
The team’s model results corroborated the theoretical calculations and gave Taruya and Okumura strong evidence that the orientations of these galaxies are related to each other, making a stronger case for general relativity on a cosmological scale.
“Current efforts, such as the Subaru Telescope project, they will provide extremely high-quality, high-precision observational data. These will spearhead groundbreaking cosmological research using intrinsic alignments to shed light on the nature of dark energy,” Taruya said.
