It turns out that the Milky Way appears to be surprisingly lighter than expected.
It’s been more than a decade since scientists have puzzled over so-called fast radio bursts (FRBs), but apparently, they could be the key to discovering something about the Milky Way. These bright flashes of ultra-short radio waves streak across the sky all day long, but surprisingly few know about them. Their origin is still unknown to experts, which is why they have attracted so much attention.
Although they remain a mystery today, new observations of this strange phenomenon could help astronomers learn more about our own galaxy. Through new research, astronomers at Caltech presented a measurement of the Milky Way’s mass using an FRB, and it turns out that the Milky Way appears to be surprisingly lighter than expected.
[Photo: NASA, ESA and B. Holwerda (University of Louisville)]
Fast Radio Bursts (FRB)
Fast radio bursts are bright and powerful emitters of radio waves lasting from a fraction of a millisecond to a few milliseconds, which are capable of producing the equivalent of the Sun’s annual energy output. They are a high-energy astrophysical phenomenon of unknown origin, although some research suggests that they originate in magnetars, which are neutron stars with extremely powerful magnetic fields.
How Is It Possible to Weigh the Milky Way?
A team of Caltech astronomers built an observatory called the Deep Synoptic Array (DSA), a collection of 110 radio antennas located in the Owens Valley in Central California, to make more precise measurements of FRBs.
The team aimed to pinpoint the precise location in the sky of each FRB they observe, so they could help figure out where these flashes originate, a task that required very detailed resolution, something like detecting a dime on the surface of the Moon.
To detect the extremely short bursts, the computers in the array must process 24 gigabytes of data per second; in other words, it would be like watching 28,000 movies from a streaming platform at the same time. The localization capability is important because, by finding out what the FRB environments are like, we will be able to tell something about their origins.
What’s interesting is that these observations not only give astronomers information about FRBs but also reveal the invisible matter that surrounds them. It turns out that more than 80% of the bacinic matter is invisible, highly scattered, and therefore difficult for telescopes to see.
Today, “the DSA is now the world’s leading instrument for this purpose,” said Vikram Ravi at the press conference at the 241st meeting of the American Astronomical Society. For last year alone, in its first year of operation, the DSA-110 helped astronomers discover 30 FRBs with precise locations.
[Photo: NASA/CXC/M.Weiss/Ohio State/A Gupta et al]
How Much Does the Milky Way Weigh?
As radio waves travel from distant galaxies to our antennas on Earth, certain frequencies of the waves will be delayed, an indicator of how much matter is between the observer and the FRB. The DSA data revealed that the Milky Way has much less regular matter than expected. Whereas most of the universe is made up of 16% regular matter and 84% dark matter. In this sense, the Milky Way has less than 10% regular matter and more than 90% dark matter.
“These results strongly support the scenarios predicted by galaxy formation simulations in which feedback processes eject matter from galaxy halos,” Ravi said. “These processes are fundamental to galaxy formation, and matter cycles in and out of galaxies,” he concluded.
Story originally published in Spanish in Ecoosfera