Astronomers have found a key connection between quasars separated by billions of light years, a hint that at its largest scale the universe may not be as homogeneous as current theories predict.

Using Europe’s Very Large Telescope in Chile, scientists looked at the polarization or angle of light coming from 93 distant quasars, which are galaxies that host very active, supermassive black holes. The black holes — regions so dense with matter than not even light can escape their gravitational hold — are surrounded by hot, spinning discs of matter that occasionally jet out along the axes of rotation.

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A larger sample is needed before scientists can make a definitive link to a larger-scale structure, but the chance that the alignment is a fluke is less than 1 percent.

The alignment could be tied to the black holes’ mass and/or how they evolved. Or it could be related to long-ago collisions and mergers of the host quasar galaxies, according to astrophysicist Damien Hutsemekers, with the University of Liege in Belgium.

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“If alignments of quasar axes with structures can explain the polarization alignments which occur on very large scales, this may challenge the cosmological principle which says that the universe is homogeneous and isotropic on very large scales,” Hutsemekers wrote in an email to Discovery News.

The research appears this week in Astronomy & Astrophysics.