14 DAY TRIAL // The Universe is a vast and mysterious place. That's obviously a huge cliche, but it doesn't make it less true. There's plenty about it that we know, but there's a lot more that we don't. Even the things we think we know, we're not sure about. Still, slowly, the Universe's mysteries are being unraveled, though often leading to more mysteries.
One of these are blazars, a mysterious source of highly-energetic gamma ray radiation that is believed to emanate from galactic cores (active galactic nuclei), similar to quasars.
Just like quasars, it is believed that blazars are the result of material falling into and being attracted by the supermassive black holes at the center of most galaxies.
Compared to quasars, blazars are much more energetic and emit gamma ray bursts that just happen to be directed straight at Earth.
These bursts don't last long, so keeping track of blazars or discovering the ones that aren't shooting a jet of radiation straight at us is hard.
But researchers are now trying to tie in blazars to infrared light emissions from active galactic nuclei (AGN).
Infrared light from these sources comes from the dust in the AGN that gets heated up by the X-ray or gamma ray bursts.
As such, the infrared light emanates in all directions, meaning we can see it from Earth even if the gamma ray burst that generates the heat is pointed in another direction.
The researchers found that blazars emit infrared light of a very particular color. As such, they believe that AGNs that show up in this color in infrared are in fact blazars, even if no gamma ray light from them reaches us at the moment.
They had the opportunity to put the theory to the test when one gamma ray source became active recently. The team looked to see if the infrared light from that region was consistent with their expectations and they found that it was.
However, this is strange as the region doesn't emit any radio waves and doesn't vary like a blazar.
This left astronomers with two explanations, either the infrared source is not the same as the gamma ray one, or this is a new type of blazar unlike any we've discovered so far. The findings are published in this week's Astrophysical Journal Letters.
There are only a few known gamma ray sources, about 1,873, and we know little about a third of them. The team found that about half to the mysterious gamma ray sources emitted infrared light of the color associated with blazars.