Astronomers have detected a mysterious and fast burst of radio emitted from a dwarf galaxy located 3 billion light-years away.
The cosmic object is distinct when compared to other radio burst detections in recent years, according to new research.
Fast radio bursts, or FRBs, are millisecond bursts of radio waves in space. Individual radio bursts are emitted once and are not repeated.
But repeating fast radio bursts is known to send out short, energetic radio waves multiple times.
Scientists have been able to trace some radio bursts back to their home galaxies, but have yet to determine the real cause of the pulsations. Learning more about the origin of these intense and bright radio emissions can help researchers understand what causes them.
Astronomers detected the object, called FRB 190520, when it released a burst of radio waves on May 20, 2019. The researchers used the Five-hundred-meter Aperture Spherical Radio Telescope, or FAST, in China and discovered the explosion in the telescope’s data. in November 2019.
When they performed follow-up observations, the astronomers noticed something unusual – the object was releasing frequent, repeated bursts of radio waves.
In 2020, the team used the National Science Foundation’s Karl G. Jansky Very Large Array, or VLA, of telescopes to pinpoint the origin of the explosion before focusing on it using the Subaru Telescope in Hawaii. Subaru’s observations in visible light showed that the explosion came from the outskirts of a distant dwarf galaxy.
A study detailing the findings published in the journal Nature on Wednesday (8).
Two types of bursts
The VLA observations also revealed that the celestial object constantly released weaker radio waves between repeated bursts. This is very similar to just one other known rapid and repeated radio burst: FRB 121102, discovered in 2016.
The initial detection and subsequent tracking of FRB 121102 back to its point of origin in a small dwarf galaxy more than 3 billion light-years away was a breakthrough in astronomy. It was the first time astronomers had been able to learn about the distance and environment of these mysterious objects.
“Now, we actually need to explain this double mystery and why FRBs and persistent radio sources are sometimes found together,” said study co-author Casey Law, a scientist on the radio astronomy team at the California Institute of Technology.
“Is it more frequent when FRBs are young? Or maybe the object making the explosions is a massive black hole that is eating a neighboring star? Theorists have a lot more detail to work with now and the scope for explanation is shrinking.”
Currently, less than 5% of the hundreds of identified fast radio bursts are known to recur and only a few of them are regularly active.
But FRB 190520 is the only one persistently active, meaning it has never “turned off” since it was discovered, said study author Di Li, chief scientist at the radio division of the National Astronomical Observatories of China and the FAST Operations Center. .
Meanwhile, FRB 121102, “the first known famous repeater, can shut down for months,” Li said.
new questions
The latest findings raise more questions because now astronomers are wondering whether there might be two types of fast radio bursts.
“Are those that repeat themselves different from those that do not? What about persistent radio emission — is this common?” asked study co-author Kshitij Aggarwal, who was involved in the research as a doctoral student at West Virginia University, in a statement.
It is possible that there are different mechanisms that cause the radio bursts, or that whatever produces them is behaving differently during various stages of evolution.
Previously, scientists 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 is being considered a possible “newborn” object because it was located in a dense environment, Law said. This environment could be caused by material released by a supernova, which resulted in the creation of a neutron star.
As this material spreads out over time, the bursts from FRB 190520 may diminish as it ages.
Going forward, Li wants to discover more fast radio bursts.
“A clearer picture of the origin and evolution of FRBs will likely emerge in just a few years,” Li said.
Law is excited about the implications of having a new class of radio wave sources.
“For decades, astronomers thought that there were basically two types of radio sources that we could see in other galaxies: supermassive black holes and star-forming activity,” Law said.
“Now we’re saying it can’t be an ‘either this or that’ categorization anymore! There is something new here and we should consider this when studying populations of radio sources in the universe.”
Source: CNN Brasil
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