A fundamental ideology in the field of cosmology that everything looks the same if you look over large distances is found not to be true. With the help of Chandra X-ray Observatory and ESA’s XMM-Newton, NASA is challenging this ideology.
“One of the pillars of cosmology – the study of the history and fate of the entire universe – is that the universe is ‘isotropic,’ meaning the same in all directions,” said Konstantinos Migkas of the University of Bonn in Germany, who led the new study. “Our work shows there may be cracks in that pillar.”
Generally, it is agreed that the universe is ever-expanding since the big bang and thought it to be expanding uniformly in all the directions. Scientists previously had made studies over the same topic and had produced possible evidence saying our universe is not isotropic.
However, the latest tests arrived at this by studying the x-ray luminosity of the star clusters at the far end of our universe. This method is independent of cosmological quantities.
The team also compared this work with studies from other groups that have found indications of a lack of isotropy using different techniques. They found good agreement on the direction of the lowest expansion rate.
For the universe, not being the same in all directions, one reason could be the presence of dark energy (this is the force which drives the expansion of the universe) itself is not uniform. In other words, x-rays may reveal that dark energy is stronger in some parts of the universe.
A paper describing these results will appear in the April 2020 issue of the journal Astronomy and Astrophysics and is available online. In addition to Migkas, Schellenberger and Reiprich, the authors of this paper are Florian Pacaud and Miriam Elizabeth Ramos-Ceja (University of Bonn), and Lorenzo Lovisari (CfA).
NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.
– Anirudh
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