Strange radio bursts from a faraway galaxy pinpointed by astronomers

5 Jan 2017

The radio signals, captured by radio telescopes in New Mexico, originated in a dwarf galaxy 3bn light years away. Image: solarseven/Shutterstock

The origin of mysterious cosmic radio bursts from a faraway galaxy has been pinpointed by astronomers using radio telescopes.

Known as fast radio bursts (FRBs), the phenomena were first discovered in 2007 in archived data from the radio telescope in Parkes Observatory, Australia, when astronomers were searching for new examples of magnetised neutron stars called pulsars.

In all, 18 have been discovered, with the oldest dating as far back as 2001.

The location of the radio signals, also known as flashes or sizzles, have been difficult to pinpoint due to their brevity.

Various theories on the causes of the signals range from black holes to extra-terrestrial intelligence.

A cosmic event

Now, astronomers who have based their research on a network of powerful telescopes, have managed to capture an FRB that is broadcasting from a dwarf galaxy 3bn light years away.

The discovery was described in papers in Nature and the Astrophysical Journal Letters.

The astronomers relied on the Karl G Jansky Very Large Array (VLA), a collection of 27 radio telescopes in New Mexico that are spread out in a Y shape to make their discovery.

This enabled them to capture the repeating FRB and then identify what galaxy it came from, and how fast the galaxy was moving away from Earth, using its spectrum of light.

The astronomers, led by Sami Chatterjee, an astronomer at Cornell University, said in their paper: “Our precise localisation reveals that FRB-121102 originates within 100 milliarcseconds of a faint 180-microJansky persistent radio source with a continuum spectrum that is consistent with non-thermal emission, and a faint (25th magnitude) optical counterpart.”

“The flux density of the persistent radio source varies by around 10pc on day timescales, and very long baseline radio interferometry yields an angular size of less than 1.7 milliarcseconds.

“Our observations are inconsistent with the fast radio burst having a galactic origin or its source being located within a prominent star-forming galaxy. Instead, the source appears to be co-located with a low-luminosity active galactic nucleus or a previously unknown type of extragalactic source.”

Now that the astrophysicists have discovered the location of the source of the radio bursts, it will make it easier for them to understand their origins.

One of the things the scientists are keen to understand is how powerful the signals were originally and how much space junk – gas and plasma – they had to travel through, and for how long, before the telescopes on earth captured them.

So far, there has been no single explanation for their origin; they could be a black hole being ripped apart, or a collision of neutron stars, or possibly a sign that there is life out there.

John Kennedy is a journalist who served as editor of Silicon Republic for 17 years