A flash of luck helped astronomers solve the cosmic mystery: What causes powerful but fleeting rapid radio signals that occasionally come from the universe? Scientists have known about these energy pulses for 13 years and all were coming from outside our galaxy. Simply said, this made it impossible to trace them and find a cause, especially given the fact that they happen in the span of a few milliseconds only.
Then this April, a rare but much weaker explosion coming from our own Milky Way galaxy was spotted by two different telescopes: one set of hand-made antennas by a doctoral student from California, and the other a Canadian observatory for $20 million.
They tracked this rapid radio burst to a strange type of star called a magnetar that is 32,000 light-years from Earth, according to research published in the journal Nature.
Magnetars and Radio Signals from Space
This was not only the first rapid radio signal in space traced to a source but also the first burst of radio waves emitted within our own galaxy.
Astronomers say there may be other sources for these eruptions, but now they are sure of only one: the magnetars.
Magnetars are incredibly dense neutron stars, with 1.5 times the mass of the Sun, pressed into space the size of a small city. They have huge magnetic fields that contain huge amounts of energy, and sometimes X-rays and radio waves erupt from them.
The magnetic field around these magnetars “is so strong that all the atoms nearby are torn apart and strange aspects of fundamental physics can be seen,” said astronomer Casey Lowe of the California Institute of Technology, who is not part of the study.
According to astronomers, even the most powerful radio bursts in space, coming from outside our galaxy, are not dangerous to us. Still, radio signals that come from outside our galaxy and travel millions or billions of light-years are “tens of thousands to millions of times more powerful than anything we’ve found in our galaxy,” said co-author Daniele Micili, an astrophysicist at McGill and part of the Canadian team.
Scientists estimate that they are so common that they can occur more than 1,000 times a day outside our galaxy. But finding them is not easy. We need to observe the exact place in the exact millisecond. Unless we are very, very lucky, we will not see any of them. Although radio bursts are a common phenomenon outside the Milky Way, astronomers have no idea how often these eruptions occur in our galaxy.
Locating the source
The Canadian Observatory in British Columbia is a lot more sophisticated than similar institutes elsewhere and focuses on a much smaller part of the sky. Thanks to this, it was able to pinpoint the source next to the magnetar in the constellation Vulpecula.
Because the bursts affect all the space and matter they pass through, astronomers may be able to use them to understand invisible material between galaxies and “weigh” the universe.
Astronomers have had various theories about what causes these rapid radio signals in the form of bursts of radio waves in space, including extraterrestrial intelligence, and they point out that magnetars may not be the only answer, especially since there appear to be two types of fast radio bursts.
Some, such as the one seen in April, occur only once, while others re-occur frequently. Michili says his team tracked an outbreak that occurs every 16 days in a nearby galaxy and is making progress in approaching the source.
Some of these young magnetars are only a few decades old, and that’s what gives them enough energy to produce repetitive rapid radio bursts. According to the team of scientists, nobody believed that they would ever have such luck, and finding such a radio signal coming from our own galaxy is astonishing.