image: A 3-D map of the universe spanning 12 to 14.5 billion light years. view more
Credit: NAOJ; Partial data supplied by: CFHT, SDSS
An international team led by Japanese researchers has made a 3D map of 3000 galaxies 13 billion light years from Earth, and found that Einstein's general theory of relativity is still valid.
Since it was discovered in the late 1990s that the universe is expanding at an accelerated rate, scientists have been trying to explain why. The mysterious dark energy could be driving acceleration, or Einstein's theory of general relativity, which says gravity warps space and time, could be breaking down.
To test Einstein's theory, a team of researchers led by Kavli Institute for the Physics and Mathematics (Kavli IPMU) Project Researcher Teppei Okumura, Kavli IPMU Project Assistant Professor Chiaki Hikage, University of Tokyo Department of Astronomy Professor Tomonori Totani, and together with Tohoku University Astronomical Institute Associate Professor Masayuki Akiyama and Kyoto University Department of Astronomy Associate Professor Fumihide Iwamuro and Professor Kouji Ohta, used FastSound Survey data on more than 3000 distant galaxies to analyze their velocities and clustering.
Their results indicated that even far into the universe, general relativity is valid, giving further support that the expansion of the universe could be explained by a cosmological constant, as proposed by Einstein in his theory of general relativity.
"We tested the theory of general relativity further than anyone else ever has. It's a privilege to be able to publish our results 100 years after Einstein proposed his theory," said Okumura.
"Having started this project 12 years ago it gives me great pleasure to finally see this result come out," said Karl Glazebrook, Professor at Swinburne University of Technology, who proposed the survey.
No one has been able to analyze galaxies more than 10 billion light years away, but the team managed to break this barrier thanks to the FMOS (Fiber Multi-Object Spectrograph) on the Subaru Telescope, which can analyze galaxies 12.4 to 14.7 billion light years away. The Prime Focus Spectrograph, currently under construction, is expected to be able to study galaxies even further away.
Details of this study were published online on April 27 in the Publications of the Astronomical Society of Japan.
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Journal
Publications of the Astronomical Society of Japan