January 5, 2017
In a first, scientists trace cosmic radio burst to tiny galaxy
Ever since they were first discovered in 2007, Fast Radio Bursts (FRBs) have baffled astronomers, but now, a new study has revealed one source of the signals – a distant galaxy more than 3 billion light years away.
FRB are strong, quick bursts of radio waves. Their briefness and mysterious origins have confounded astronomers and the new research, published in the journal Nature, sheds significant light on what may be causing them."I don't exaggerate when I say there are more theories for what these could be than there are observed bursts," study author Shami Chatterjee, from Cornell University, told the BBC.
Discovered in 2007 in archived data from 2001, FRBs were discovered using single-dish radio telescopes that cannot pinpoint the sources' locations with sufficient precision to help describe the flashes.
To further investigate the phenomena, researchers utilized a multiple-antenna radio telescope known as the Karl G Jansky Very Large Array (VLA) in New Mexico, which had adequate resolution to figure out the positioning of a flash referred to as FRB 121102. Unlike most other FRBs, this event discovered 2012 has recurred multiple times.
"When we reported last year that one of these objects was repeating, that - in one go - knocked out about half of those models, because for this one source, at least, we knew it couldn't be explosive. It had to be something where the engine that produced this survived for the next flash,” Chatterjee said.
Detecting Fast Radio Bursts
Over the course of six months in 2016, the VLA detected nine bursts from FRB 121102. "We now know that this particular burst comes from a dwarf galaxy more than three billion light-years from Earth," Chatterjee said.
The size of the distance and the fact that we can still detect these signals shows the significant power of these flashes.
"That simple fact is a huge advance in our understanding of these events,” the Cornell astronomer said.
The team was also able to observe a regular, prolonged source of fainter radio emission in the same area. The flashes and the continual source must be within 100 light-years of one another, and researchers said they are probably either coming from the same object or physically connected with each other.
"This persistent radio source could be an active galactic nucleus (AGN) at the centre of a galaxy that's feeding (consuming matter from its surroundings), sending out jets, and these sizzles we see are little bits of plasma being vaporized in the jets," Chatterjee said. "That's not the interpretation we favor. The one we favor is that maybe it's a baby magnetar - a neutron star with a massive magnetic field - and it's got a nebula surrounding it that's powered by the energy being lost by this object. Every once in a while, we're getting a flash from this baby magnetar."
Despite this promising development, more research will be needed to figure out if all FRBs are caused by the same source or if they can have different sources.
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