Bright Radio Bursts Delve Into Universe’s Hidden Matter

Fast radio bursts, abbreviated FRBs, are mysterious flashes of radio waves that come from outside our Milky Way galaxy.
A team of scientists,  led by the combined efforts of Caltech  scholar Vikram Ravi and Curtin University research fellow Ryan Shannon,
has now observed the most luminous radio burst to date, called FRB 150807.

Astronomers still are in the dark about what kinds of events or objects produce FRBs,
the discovery is a big step for astronomers to understand the spread out,
dim web of material that exists between galaxies, named the cosmic web.

“Because Fast Radio Bursts like the one we discovered occur billions of light-years away,
they help us study the universe between us and them,” says Ravi.
“Nearly half of all visible matter is thought to be thinly spread throughout intergalactic space.
Although this matter is not normally visible to telescopes, it can be studied using FRBs.”

When Fast Radio Bursts travel through space, they pass through intergalactic material and are distorted,
similar to the blinking of a star because its light is distorted by Earth’s atmosphere.
By observing them, astronomers can learn details about the regions of the universe from
which the bursts traveled on their way to Earth.

FRB 150807 appears to only be slightly distorted by  the material within its host galaxy,
which shows that the intergalactic space in this direction is no more unstable than theorists originally predicted.
This gives us the first direct insight into turbulence in intergalactic space.

The researchers observed FRB 150807 while monitoring a nearby pulsar
in the Milky Way using the Parkes radio telescope in Australia.
“Thanks to a real-time detection system developed by the Swinburne University of Technology,
we found that although the FRB is a million times further away than the pulsar,
the magnetic fields in their directions appear identical,” says Ryan Shannon,
research fellow , and co-lead author of the study.
This contradicts some claims about FRBs being produced in dense environments with strong magnetic fields.
This result provides a measure  in the space between galaxies to determine the strength of the magnetic field , an important step
in determining how cosmic magnetic fields are produced.
Most Fast Radio Bursts have been detected with telescopes that observe large areas of the sky, however they are with poor resolution.
This increases the difficulity  of finding  the exact location of a given burst. The large  brightness of FRB 150807 allowed Ravi
and his team to localize it much more accurately, making it the best-localized FRB to date.

In February 2017, indentifying the locations of those radio bursts will become far easier for astronomers with the commissioning
of the Deep Synoptic Array prototype, an array of 10 radio dishes at Caltech’s Owens Valley Radio Observatory in California.

“We estimate that there are between 2,000 and 10,000 FRBs occurring in the sky every day,”. Ravi says.
“One in 10 of these are as bright as FRB 150807, and the Deep Synoptic Array prototype will be able to pinpoint their
locations to individual galaxies. Measuring the distances to these galaxies enables us to use FRBs to weigh the tenuous
intergalactic material.”

The Deep Synoptic Array prototype, is being constructed by the
Jet Propulsion Laboratory (JPL) and Caltech and gets its funds by the National Aeronautics and Space Administration through the
JPL President’s and Director’s Fund Program.


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