Black Holes Offer a New Surprise: They All Spin in the Same Direction

One of astronomy’s most secretive phenomena, black holes, has yielded yet another fascinating puzzle to astronomers — and in the process, offering what may be new insight into how the universe formed. A recent survey of a region of deep space has found that the powerful jets that are propelled by some supermassive black holes are uncannily aligned, all pointing in the same direction.

Using the Giant Metrewave Radio Telescope in India, researchers from South Africa’s University of Cape Town and University of the Western Cape surveyed a small, 1 degree portion of the sky, scanning for deep-space radio signals. The survey was originally intended to search for the faintest radio signals that could be detected, but in the process, they discovered the odd alignment of the relativistic jets of black holes.

These jets are the byproduct of material from a black hole’s accretion disk, having been drawn into the black hole’s gravity well: not all of the material is captured by the singularity’s event horizon, with some of this material missing it’s surface and being accelerated to just shy of the speed of light as it is pulled past. The spin of the black hole causes the material, now converted to a plasma by the powerful stresses it experiences, to be ejected in jets that are aligned with the singularity’s poles. Because of the force of the ejection, some of these jets can be between several thousand to hundreds of thousands of light-years long.

The parallel alignment that these jets exhibit can’t be because of black holes directly affecting one-another, since the same phenomenon is being seen in different galaxies, far, far away from one another. However, the study does offer a theory that may explain the odd phenomenon: "Since these black holes don’t know about each other, or have any way of exchanging information or influencing each other directly over such vast scales, this spin alignment must have occurred during the formation of the galaxies in the early universe," explains professor Andrew Russ Taylor, principal author of the study. Radio telescope arrays that will offer even greater sensitivity are currently under construction, and may help further our understanding of phenomena such as this.