Strange alignment: A group of black holes points to galaxies' beginnings
A group of supermassive black holes in a distant region of space are all shooting radio emissions in the same direction, despite having no way to transmit information.
Credit: Prof Russ Taylor/Royal Astronomical Society
Black holes became a little more inexplicable this week.
On Monday, researchers from South Africa published findings of a region in the universe called ELAIS-N1, where 64 supermassive black holes are all emitting radio jets in the same direction.
Radio jets, emissions of radio waves from the black holes thought to be at the centers of some galaxies, are familiar to scientists. But what is new and unusual are the number of black holes apparently in sync and the distance between them. Scientists have never seen so many black holes over such a large region all sending radio emissions in the same direction.
"This is not obviously expected based on our current understanding of cosmology," Romeel Dave, an astrophysicist with the University of the Western Cape, but not connected with the research, said in the press release. "It’s a bizarre finding."
The findings were unintentional. The South African scientists from the University of Cape Town and the University of the Western Cape had intended to map faint radio emissions with the help of the South African MeerKAT radio telescope and the soon-to-be-built Square Kilometre Array, which, when completed, will be the world's most powerful radio telescope.
But that plan soon gave way to a three-year survey using deep radio imaging to map the radio emissions of ELAIS-NI. The team also ended up using the Giant Metrewave Radio Telescope in India, which detected the odd black hole alignment via radio wave emissions.
What they found prompted a fresh set of questions – and theories – about black holes.
To get so many radio jets emitting in the same direction, all of the galaxies would need to be spinning in the same direction, Prof. Andrew Russ Taylor, lead author of the study, explained in the press release.
That would require a unifying force directing the spin of all the galaxies, but the ones found in the study are so far apart, they cannot possibly be currently influencing each other.
One plausible answer is that they were brought into alignment by a force older and stronger than more recently formed black holes. "This spin alignment must have occurred during the formation of the galaxies in the early universe," Dr. Taylor said.
But what force shaped the landscape of the early universe remains unclear.
The team of scientists came up with a number of possible explanations, ranging from cosmic magnetic fields to cosmic strings. But the anomaly found by the study has never been predicted before and presents a fresh challenge to astrophysicists, especially those theorizing about the early universe.
So far in 2016, researchers have discovered black holes that challenge several conventions of scientists' understanding of the cosmos. In early January, for example, scientists developed a new method for finding medium- and small-sized black holes by tracking "space storms," The Christian Science Monitor reported. But the discovery raised questions about whether the intermediate-sized black holes were hard to find, or just rare.
In April, another discovery muddied the picture around how and where black holes form, when an average-sized galaxy group was found to contain the largest black hole ever recorded. Previous research had suggested the largest black holes only formed in very dense galaxy clusters.
It doesn't appear that black holes are becoming any simpler to understand, but the more that scientists learn, the more intriguing the universe becomes.
"We’re beginning to understand how the large-scale structure of the universe came about, starting from the Big Bang and growing as a result of disturbances in the early universe, to what we have today," Taylor noted, "and that helps us explore what the universe of tomorrow will be like."