Mysterious Fast Radio Bursts Could Reveal Hidden Galactic Matter

Fast bursts of radio waves that originate millions to billions of light-years away from Earth could be used as probes to study the hard-to-see diffuse gas halos surrounding nearby galaxies.

New research shows that these pulses called fast radio bursts (FRBs), which are slow as they pass through the gas surrounding the galaxies between their source and the Earth. This also has the effect of scattering their radio frequencies.

Using this to study galactic gas halos, researchers at the California Institute of Technology (Caltech) have found twice as much material as previously believed in these envelopes that envelop galaxies. This has implications for how these collections of stars and planets evolve over large periods of time.

Related: Discovery of second repeating fast radio burst raises new questions

Astronomers examined a sample of 474 distant FRBs with the Canadian Hydrogen Intensity Mapping Experiment (CARILLON) confirming that 24 FRBs intercepted by galactic halos were indeed slowed down compared to others that made it to Earth without incident. Thus, this effect can be used to probe the material through which the FRB passes.

“Our study shows that FRBs can act as skewers of all matter between our radio telescopes and the source of the radio waves,” said Liam Connor, Tolman postdoctoral fellow in astronomy at Caltech. statement (opens in a new tab). “We used fast radio bursts to shine a light through the halos of galaxies near the Milky Way and measure their hidden matter.”

Using FRBs farther outside our galaxy to study the huge pools of gas that surround other galaxies has already revealed a surprise. Astronomers have found that there is more material in the gas halos than previously believed, about twice as much as predicted by theoretical models.

“These gas reservoirs are huge,” Connor said. “If the human eye could see the spherical halo that surrounds the nearby Andromeda galaxy, the halo would appear a thousand times larger than the moon.”

Because these gas halo are remnants of the same material that is used to form stars and planets, further investigation of them could lead to a better understanding of how galaxies evolve over time periods of billions of years.

Related: Scientists detect strange ‘fast radio burst’ in our own Milky Way

An artist’s illustration shows the 300,000 light-year-wide halo of gas surrounding the Milky Way. (Image credit: NASA/CXC/M.Weiss; NASA/CXC/Ohio State/A.Gupta et al.)

Although researchers are currently uncertain of the origin of FRBs, first detected in 2007, they believe that these pulses of electromagnetic radiation lasting from a fraction of a millisecond to a few milliseconds are emitted by stars. fast-rotating magnetic dies called magnetars.

Evidence of this connection was provided in 2020 when Caltech’s Survey for Transient Astronomical Radio Emission 2 (STARE2) instrument was paired with CHIME to detect a massive FRB. erupting in the Milky Way.

Since their discovery in 2007, hundreds of FRBs have been observed and these revelations should continue to arrive thanks, in part, to Caltech’s 110-dish. Deep Synoptic Network (opens in a new tab)or DSA-110.

The project has already identified several FRBs and traced them back to the galaxies from which they originated. Caltech scientists plan to build an even larger array of telescopes over the next few years, which will include 2,000 dishes. Called DSA-2000, the project will be the most powerful radio observatory ever built and will be able to detect and identify thousands of FRBs and their sources each year.

“This is just the beginning,” said Vikram Ravi, assistant professor of astronomy at Caltech. “As we discover more FRBs, our techniques can be applied to study individual halos of different sizes and in different environments, addressing the unsolved problem of how matter is distributed in the universe.”

The team’s research has been published (opens in a new tab) in the journal Nature Astronomy.

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