Artist’s rendering of ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun. Some of the matter falling into the hole gets beamed back into space along the axis of the spinning disk’s rotation. Credit: ESO/M. Kornmesser
Quasar. One of the coolest words ever. It’s really shorthand for “quasi stellar radio source”. When radio telescopes were developed in the latter half of the 20th century, astronomers eagerly used them to find new objects in the sky, many invisible in visible light. One of the things they found were these star-like objects glowing brightly in radio waves but appearing only as undistinguished stars in optical telescopes.
Further study revealed they were extremely distant – billions of light years – as far as the most remote galaxies. For such a tiny object to shine across such vast distances, it must be powered by something extraordinary.
We now know that quasars are galaxies with very active supermassive black holes at their centers. Matter falling a black hole gets spun into a whilring disk, releasing tremendous amounts of energy before it finally goes “down the drain” for good. Some the incandescent matter beams back into space in long jets perpendicular to the disk.
This artist’s impression shows the mysterious alignments between the spin axes of quasars and the large-scale structures that they inhabit that observations with ESO’s Very Large Telescope have revealed. These alignments are over billions of light-years and are the largest known in the universe. The large-scale structure is shown in blue and quasars are marked in white with the rotation axes of their black holes indicated with a line. This picture is for illustration only and does not depict the real distribution of galaxies and quasars. Credit: ESO/M. Kornmesser
Today, according to a news announcement by the European Southern Observatory (ESO), a European research team has found that the rotation axes of the central supermassive black holes in a sample of 93 quasars are parallel to each other over distances of billions of light-years. The team has also found that the rotation axes of these quasars tend to be aligned with the vast structures in the cosmic web in which they reside. We see the 93 quasars at a time when the universe was just a third of its current age.
Admittedly, these sounds like pretty obscure stuff, but why should these objects that are not only far from us but billions of light years from each other, be connected? It’s such an intriguing mystery, but before we look at why, let’s stop to examine the large scale structure of the universe.
This simulation, created by the Millennium Simulation Project, represents a 2 billion- light-year-wide chunk of the universe and more than 20 million galaxies. The purple strands represent dark matter around which normal matter (the bright yellow clumps of galaxies) has clustered into filaments of billions of galaxies surrounded by empty voids of space. Credit: Millenium Simulation Project
When we sit back and take in the really, really big picture, the billions of galaxies out there are arranged in dense filaments and strands resembling a pile of spaghetti or neurons in the human brain. The strands in turn are clustered about the still-mysterious dark matter, of which there’s far more of than the bright stuff like stars and galaxies. To refresh your memory, the universe is composed of 73% dark energy, 23% dark matter and only 4% bright matter.
Large pockets of relatively galaxy-free space called cosmic voids lie betwixt and between the strands. The entire texture strikingly shown in the simulation (and visible on smaller scales in maps and photos) is linked to dark matter, which though invisible, is both plentiful and makes its presence known through gravity. Dark matter forms the backbone for all the beautiful galaxies we see in our telescopes and in photos taken by the Hubble. It’s the coral reef and the galaxies are the fish, crabs and all the rest.
Artist concept of a supermassive black hole powering a quasar. Black holes that form from the collapse of a star during a supernova explosion are only a few miles across. Supermassive ones, built up over billions of years from matter straying too close the hole’s event horizon, are the size of the solar system. Our Milky Way harbors such a supermassive black hole, but it’s currently not active like those seen in quasars. Credit: Wiki
The new VLT results indicate that the rotation axes of the quasars tend to be parallel to the large-scale structures in which they find themselves. So, if the quasars are located in one of the spaghetti noodle, then the spins of the central black holes will point along the axis of that noodle. The researchers estimate that the probability that these alignments as simply the result of chance is less than 1%.
Take a journey through the large-scale structure of the universe in this video version of the photo above.
By the way, the research team, led by Damien Hutsemékers from the University of Liège in Belgium, could not see the rotation axes directly but inferred them by measuring the polarization (light waves vibrating in a preferred direction) of the quasars’ light.
So the “why” of these spooky alignments is this: we don’t know … yet:
“The alignments in the new data, on scales even bigger than current predictions from simulations, may be a hint that there is a missing ingredient in our current models of the cosmos,” concludes Dominique Sluse.
Are they following the dictates of the unseen dark matter? Hmmm … questions as always. This is the beauty of going where no one has ventured before.