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Physics + MathPhysics & Math

Quasars Show 'Spooky' Alignment Across Billions of Light Years

A new study suggests that quasars’ rotation axes are aligned with one another despite that they're separated by billions of light-years.

ByAllison EckNOVA NextNOVA Next
Cosmologists are studying galaxy and quasar alignment (depicted here by an artist) to understand how the universe makes order out of chaos.

When the universe was one-third its current age, distant cosmic phenomena called quasars spewed light in all directions.

Today, that light has made it to Earth—and cosmologists that are studying it to understand how the universe makes order out of chaos.

A quasar is a compact region that surrounds a supermassive black hole in the center of a large galaxy. While scientists suspect that most large galaxies have quasars, not all of them are active. The distinction between active and inactive has to do with angular momentum: if the matter surrounding the black hole has some angular momentum, then it will avoid falling directly into the black hole and will instead collect into what’s known as an “accretion disc” around the circumference. The accretion disc is what causes quasars’ intense luminosity and high energy output. A quasar can also be activated if galaxies merge and the black hole gets a new supply of matter.

While galaxies all have nuclei—active quasars or not—galaxies themselves are not evenly distributed throughout the universe, even across distances spanning billions of light-years. Instead, galaxies form cosmic “webs” that weave around huge chambers of darkness. Shimmering filaments thread galaxies together, and brighter parts of those filaments are home to large galaxy clusters. Previous studies have shown that galaxies seem to spin on axes parallel to whatever filament hosts them. That discovery alone was surprising enough to scientists. But a new study assessing quasar alignment takes this “spooky” effect even further.

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Here’s Xaq Rzetelny, writing for ArsTechnica:

The study, which makes use of observations from the Very Large Telescope taken in March, examines 93 extremely bright yet distant quasars (because of their distance, we see the light the quasars produced when the Universe was only a third of its age). “The first odd thing we noticed was that some of the quasars’ rotation axes were aligned with each other—despite the fact that these quasars are separated by billions of light-years,” Damien Hutsemékers, the paper’s lead author, told ESO . That led them to wonder if the quasars were aligned not just with each other but with their filaments. To test their hypothesis, the researchers examined the quasars’ polarization.

The polarization angle of the light—the direction light waves oscillate—coming from the quasar is either parallel or perpendicular to the quasar’s accretion disk (the ring of gas and energy formed as matter falling into the black hole gives rise to frictional heating). So knowing the polarization angle of the quasar’s light enables scientists to deduce the orientation of the quasar’s rotation axis, as well. Of the 93 quasars the team examined, 19 demonstrated a significantly polarized signal, meaning the team was able to calculate their orientation with respect to the overall filament.

What they found is that all 19 quasars are, most likely, spinning parallel to their filaments (though that doesn’t necessarily mean the quasar rotation is aligned with its galaxy’s rotation). But since galaxies are similarly aligned to their respective filaments, astrophysicists suspect that there’s less than a 1% chance of this result being completely random. In other words, some common mechanism is putting these celestial objects in place. That missing factor, they say, could be instrumental in helping us grasp how our universe was built.

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Photo Credit: ESO/M. Kornmesser