(CNN) — Astronomers have detected a mysterious fast and repeating radio burst emanating from a dwarf galaxy 3 billion light-years away.
The cosmic object is peculiar when compared to other radio burst detections in recent years, according to new research.
Las fast Radio Bursts, or FRB, are millisecond-long bursts of radio waves in space. Individual radio bursts are emitted once and are not repeated. But fast repeating radio bursts are known to send out short, vigorous radio waves multiple times.
Astronomers have been able to trace some radio bursts back to their home galaxies, but have not yet determined the actual cause of the pulses. Learning more regarding where these bright, intense radio emissions come from might help scientists understand what causes them.
This image, taken by the Karl G. Jansky Very Large Array, shows object FRB 190520 when it is active (in red).
Astronomers detected the object, dubbed FRB 190520, when it emitted a burst of radio waves on May 20, 2019. The researchers used the 500-meter-aperture FAST radio telescope in China and discovered the burst in the telescope’s data. in November 2019. Astronomers carried out follow-up observations and noticed something unusual: The object was releasing frequent and repeated bursts of radio waves.
In 2020, the team used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) astronomical observatory to locate the origin of the burst before focusing on it using the Subaru Telescope in Hawaii. Subaru’s visible-light observations showed that the burst came from the outskirts of a distant dwarf galaxy.
And study detailing the findings was published Wednesday in the academic journal Nature.
two of its kind
The VLA observations also revealed that the celestial object was constantly emitting weaker radio waves between repeated bursts. This is very similar to another known fast repeating radio burst: FRB 121102, discovered in 2016.
The initial detection and subsequent tracking of FRB 121102 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 that astronomers were able to know the distance and environment of these mysterious objects.
“Now we have to explain this double mystery and why FRBs and persistent radio sources are sometimes found together,” said study co-author Casey Law, a radio astronomy staff scientist at the California Institute of Technology. “Is it common when FRBs are young? Or perhaps the object causing the outbursts is a huge black hole that is messily gobbling up a neighboring star? Theorists now have much more detail to work with and the scope for explanation is widening.” reduce”.
Currently, less than 5% of the hundreds of identified fast radio bursts are known to be repeating, and only a few are regularly active.
But FRB 190520 is the only continuously active radio burst, 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 from the FAST Operations Center. Meanwhile, FRB 121102, “the earliest known famous repeater, can go dark for months,” Li said.
new questions
Recent discoveries raise more questions, and now astronomers are wondering if there might be two types of fast radio bursts.
“Are those that repeat different from those that don’t? And persistent radio emission, is it common?” said study co-author Kshitij Aggarwal, who participated in the study as a doctoral student at the University of Virginia. Western, in a statement.
It is possible that there are different mechanisms that cause radio bursts, or that what causes them behaves differently during different stages of their development.
Previously, scientists hypothesized that fast radio bursts are caused by the dense remnants left behind following a supernova, called neutron stars, or by neutron stars with incredibly strong magnetic fields called magnetars.
This is an artist’s concept of a neutron star with an ultrastrong magnetic field, called a magnetar, that emits radio waves (shown in red).
FRB 190520 is considered a possible “newborn” object because it was found in a dense environment, Law said. That environment may be caused by material released by a supernova, which led to the creation of a neutron star. Because this material disperses over time, FRB 190520’s bursts may decrease as it ages.
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 in a few years,” Li says.
Law is excited regarding 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 might see in other galaxies: growing supermassive black holes and star-forming activity,” Law said. “Now we say that it can no longer be categorized as one or the other! There is a new possibility and we need to take it into account when studying the populations of radio sources in the universe.”