Astronomers detect 1,652 rapid radio bursts from source in distant dwarf galaxy

Astronomers using the new Five Hundred Meter Aperture Spherical Radio Telescope (FAST) have detected 1,652 independent burst events from source FRB 121102 – which is located some 3 billion light years away in the constellation Auriga – on a period of only 47 days.

Since rapid radio bursts (FRBs) were first discovered in 2007, astronomers around the world have turned to powerful radio telescopes like FAST to trace the bursts and search for clues as to their origin and production.

The source that powers most FRBs is widely believed to be magnetars, incredibly dense neutron stars that have the strongest magnetic fields in the Universe.

And while scientists gain clarity on what produces FRBs, the exact location where they occur is still a mystery.

“There are two active models of where FRBs come from,” said Dr. Bing Zhang, an astronomer in the Department of Physics and Astronomy at the University of Nevada.

“One could be that they originate in magnetospheres, or in the strong magnetic field of a magnetar. Another theory is that FRBs form from relativistic shocks outside the magnetosphere moving at the speed of light.

The new results pose great challenges to this latest model, ”he said.

“The bursts are too frequent and – given that this episode alone represents 3.8% of the energy available from a magnetar – it is too much energy for the second model to work.”

FRB 121102 was first detected in 2012 by astronomers using the Arecibo Observatory radio telescope.

Two years later, they discovered that FRB 121102 was a recurring source, and a year later, they located it in a dwarf galaxy some 3 billion light years away.

“From this source, 1,652 rapid radio bursts are a surprising number,” said Dr. Shami Chatterjee, an astronomer at the Cornell Center for Astrophysics and Planetary Science and the Department of Astronomy at Cornell University.

“Until now, astronomers were talking about a handful of bursts – a few, then maybe 10 and maybe 25. But now they’re talking about over 1,600 bursts over 47 days. It is really dramatic.

The bursts were measured by FAST over a total of 59.5 hours over 47 days from August 29 to October 29, 2019.

“During its most active phase, FRB 121102 consisted of 122 bursts measured over an hour-long period, the highest repetition rate ever observed for an FRB,” said Dr. Pei Wang, astronomer at the Astronomical Observatories. nationals of the Chinese Academy of Sciences. .

“Whatever is producing these bursts, it must be incredibly energetic,” noted Dr. Chatterjee.

“Having a large number of bursts on any given day, we still cannot identify its period,” said Professor James Cordes, an astronomer at the Cornell Center for Astrophysics and Planetary Science and the Department of Astronomy at Cornell University.

“We know that a rotating object like a pulsar – which has a lighthouse-like beam – has a specific period. But this FRB is more of a puzzle.

“There could be a neutron star involved, but we have no indication of a periodicity. This deepens the mystery.

An article on the results has been published in the journal Nature.

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D. Li et al. 2021. A bimodal burst energy distribution from a repetitive fast radio burst source. Nature 598, 267-271; doi: 10.1038 / s41586-021-03878-5