Radio burst detected in dwarf galaxy

Astronomers have detected a mysterious, fast, repeating radio burst emanating from a dwarf galaxy located three billion light-years away.

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

Fast Radio Bursts, or FRBs, are millisecond-long bursts of radio waves in space. Individual radio bursts transmit once and do not repeat.

But repeating fast radio bursts are known to send short, energetic radio waves multiple times.

This image, captured by the Karl G. Jansky Very Large Array, shows object FRB 190520 when active (in red).
This image, captured by the Karl G. Jansky Very Large Array, shows object FRB 190520 when active (in red). (CNN)

Astronomers have been able to trace some radio bursts back to their home galaxies, but have yet to determine the actual cause of the pulses. Knowing more about the origin of these bright and intense radio emissions could help scientists understand what causes them.

Astronomers detected the object, named FRB 190520, when it emitted a burst of radio waves on May 20, 2019. Researchers used the Five Hundred Meter Aperture Spherical Radio Telescope, or FAST, in China, and have discovered the burst in the telescope. November 2019 data.

When making follow-up observations, the astronomers noticed something unusual – the object was emitting frequent and repeated bursts of radio waves.

In 2020, the team used the Karl G. Jansky Very Large Array, or VLA, of National Science Foundation Telescopes to identify the origin of the burst before focusing on it using the Subaru Telescope in Hawaii. .

Subaru’s visible-light observations showed that the burst originated from the outskirts of a distant dwarf galaxy.

A study detailing the findings published in the journal Nature on Wednesday.

VLA observations also revealed that the celestial object was constantly releasing weaker radio waves between repeated bursts. It’s very similar to only one other known repeating fast radio burst: FRB 121102, discovered in 2016.

The initial detection and subsequent tracing of FRB 121102 to its point of origin in a small dwarf galaxy more than three billion light-years away was a breakthrough in astronomy. It was the first time astronomers could learn more about the distance and surroundings of these mysterious objects.

“Now we actually need to explain this double mystery and why FRBs and persistent radio sources sometimes end up together,” said study co-author Casey Law, a radio astronomy researcher at the California Institute of Technology.

“Is this common when FRBs are young? Or maybe the object making the bursts is a massive black hole devouring a nearby star in a haphazard fashion? Theorists have a lot more details to work out now and the scope of explanation narrows.”

This is an artist's concept of a neutron star with an ultra-strong magnetic field, called a magnetar, emitting radio waves (in red).
This is an artist’s concept of a neutron star with an ultra-strong magnetic field, called a magnetar, emitting radio waves (in red). (CNN)

Currently, less than five percent of the hundreds of identified fast radio bursts repeat themselves and only a few of them are regularly active.

But FRB 190520 is the only persistently active one, meaning it has never “gone out” since its discovery, said study author Di Li, chief scientist of the Observatories’ radio division. National Astronomical Institutes of China and the FAST Operation Center.

Meanwhile, FRB 121102, “the first known famous repeater, may die out for months,” Li said.

The latest findings raise more questions as astronomers now wonder if there could be two types of fast radio bursts.

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

It is possible that there are different mechanisms that cause radio bursts, or that what produces them behaves differently during different evolutionary stages.

Previously, scientists had speculated that fast radio bursts were caused by the dense remnants of a supernova, called a neutron star, or neutron stars with incredibly strong magnetic fields called magnetars.

FRB 190520 is considered a possible “newborn” object because it was located in a dense environment, Law said. This environment may be caused by materials released by a supernova, which resulted in the creation of a neutron star. As this material disperses over time, the splinters of FRB 190520 may decrease as it ages.

In the future, Li wants to experience faster radio bursts.

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

NASA’s new telescope captures ‘unprecedented’ detail

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 we could see in other galaxies: accretion of supermassive black holes and star-forming activity,” he said. Law.

“Now we’re saying that can’t be an either/or categorization anymore! There’s a new kid in town and we should take that into account when we study the populations of radio sources in the universe.”

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