Radio waves detected in explosion from dwarf galaxy billions of light years away

Astronomers have discovered a mysterious, repeating fast radio burst from a dwarf galaxy 3 billion light-years away.

The cosmic object is distinctive compared to other detections from radio bursts in recent years, according to new research.

Watch the video above to see the first time a high-speed radio blast was traced to its source

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Fast radio bursts, or FRBs, are bursts of radio waves in the space of milliseconds.

Individual radio bursts broadcast once and are not repeated. But repeating high-speed radio bursts are known to emit short, energetic radio waves multiple times.

Astronomers have been able to trace some radio bursts back to their own galaxies, but they have yet to determine the actual cause of the pulses.

By learning about the origin of these bright, intense radio emissions, scientists can understand what causes them.

Astronomers discovered the object, called FRB 190520, when it emitted a burst of radio waves on May 20, 2019.

The researchers used the 500-meter Aperture Spherical Radio Telescope (FAST) in China and discovered the burst in the telescope data in November 2019.

When they conducted follow-up observations, the astronomers noticed something unusual: The object gave off frequent, repetitive bursts of radio waves.

An artistic concept of a neutron star with an ultra-strong magnetic field called a magnetar, which emits radio waves (in red). Credit: Bill SaxtonNRAO/AU/NSF

In 2020, the team used the Karl G. Jansky Very Large Array (VLA) of National Science Foundation telescopes to locate the burst’s origin before zeroing it using the Subaru Telescope in Hawaii.

Subaru’s visible light observations showed that the eruption came from the edge of a distant dwarf galaxy.

A study detailing the findings was published in the log Nature on Wednesday.

Two of a Kind

The VLA observations also revealed that the celestial body continuously emitted weaker radio waves between the repeating bursts.

That’s very similar to just one other known repetitive fast radio burst: FRB 121102, discovered in 2016.

The initial detection and subsequent detection of FRB 121102 back to the starting point in a small dwarf galaxy more than 3 billion light-years away was a breakthrough in astronomy.

It was the first time astronomers could learn the distance and environment of these mysterious objects.

This image, taken by the Karl G. Jansky Very Large Array, shows the object FRB 190520 when it is active (in red). Credit: NRAO, Bill SaxtonNSF, AUI, CFHT

“Now we really need to explain this twin mystery and why FRBs and persistent radio sources are sometimes found together,” said Casey Law, co-author and staff scientist at the California Institute of Technology in radio astronomy.

“Is it common when FRBs are young? Or maybe the object making the outbursts is a huge black hole that is slovenly eating a neighboring star?

“Theorists now have much more detail to work with and the space for explanation is narrowing.”

Currently, less than 5 percent of the hundreds of identified fast radio bursts are known to recur, and only a few of them are active on a regular basis.

But FRB 190520 is the only persistently active one, meaning it’s never “turned off” since it was discovered, said study author and National Astronomical Observatories of China and lead scientist Di Li of the radio division of the FAST Operation Center.

Meanwhile, FRB 121102, “the first known famous repeater, could be disabled for months,” Li said.

New questions for FRBs

The latest findings raise more questions as astronomers now wonder whether there are two types of fast radio bursts.

“Are those who repeat different from those who don’t? What about the ongoing radio emission – is that common?” a study co-author involved in the study as a doctoral student at West Virginia University, Kshitij Aggarwal, said in a statement.

It’s possible that there are different mechanisms causing the radio bursts, or that whatever produces them behaves differently during different stages of evolution.

Previously, scientists have hypothesized that fast radio bursts are caused by the dense remnants left over after a supernova, called a neutron star, or neutron stars with incredibly strong magnetic fields called magnetars.

FRB 190520 was considered a possible “newborn” object because it was in a dense environment, Law said.

That environment could be caused by material released during a supernova, creating a neutron star.

Since this material scatters over time, FRB 190520’s bursts may decrease with age.

In the future, Li wants to discover more fast radio bursts.

“A coherent picture of the origin and evolution of FRBs is likely to emerge within a few years,” Li said.

Law is excited about the implications of having a new class of radio wave sources.

“For decades, astronomers thought there were basically two types of radio sources that we could see in other galaxies: accreting supermassive black holes and star-forming activity,” Law said.

“Now we say it can’t be either/or categorization anymore!”

“There’s a newbie in town and we need to take that into account when studying populations of radio resources in the universe.”

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