Mystery flares: Edmonton astronomer stumped by his own discovery

For Edmonton astronomer Gregory Sivakoff, the sight of never-before-seen explosions in space was the find of a lifetime.

In two galaxies not so far away, researchers have uncovered two mysterious objects that erupt with powerful X-rays.

“These are very rare phenomena,” said Sivakoff, a University of Alberta researcher who co-authored a recently published study on the galactic anomalies.

“We’ve never seen anything that flares this brightly and repeats like this.”

The discovery, obtained with data from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton Observatory, may represent a whole new kind of explosive event.

What the heck are they? 

The research team, made up of scientists from 10 international institutions, detected seven of the massive energy flares within two stars after looking at over a decade’s worth of archived data from the observatories.

“We were looking at nearby galaxies and trying to understand whether any of these were very variable, whether there were any bright spots in these galaxies which would just ‘wow’ us,” Sivakoff said in an interview with CBC Radio’s Edmonton AM.

“We didn’t just find one, we found two. We looked through over 70 galaxies.”

The mysterious sources regularly emit X-rays, but also spontaneously flare up, becoming about 100 times brighter within a minute.

But unlike supernovas, which are destroyed and collapse under the power of huge surges in energy, these two sources flare intensely to the verge of exploding, only to simmer back to baseline within an hour.

They repeat the process every few days, in an oddly unpredictable pattern.

‘Astrophysics can be complicated’

The source of all those radioactive flares remains a mystery, Sivakoff said.

“In science, when you discover something, you’re really excited, and you have to announce it to the world but you don’t quite know what it is. But we have a few ideas.

“Astrophysics can be complicated, which is why I call it astronomy before I talk to people.”

The sporadic surges are “so darn bright” and rapid, Sivakoff says they can likely only be explained by the presence of two things: black holes and neutron stars.

“For a neutron star, imagine if you took the mass of the sun and compacted it down to the size of Edmonton. It’s very dense, very strange. Black holes go even farther and they collapse down to a single point,”  Sivakoff said. 

“You can get a lot of energy from these type of sources.” 

‘They’re chowing down’

The flares are likely caused by matter from a nearby star falling into black holes or neutron stars. And the researchers believe when the objects aren’t flaring up, they slowly suck up material around them into large discs.

“We think there is a nearby star and it’s feeding these black holes and these neutron stars and its feeding them at a pretty good rate, so they’re chowing down.”

“But all of a sudden, something happens, and the food comes down the chute faster.”

Future research with ultraviolet and radio wavelengths might help investigate the source of these strange, newly discovered phenomena.

Although the flares remain a mystery for now, Sivakoff hopes that they will one day serve as important predictors of changes in the universe.

“[In astrophysics] you have these patterns, an unexplained phenomena. Sometimes for years they remain unexplained,” said Sivakoff.

“But then we understand the physics and it becomes a tool.” 

“And I think that’s what this will likely be. I’m really excited to be involved in this because I think this is the beginning of something big.”