- 4284 - RADIO WAVE BURSTS - Astronomers have discovered the most ancient "heartbeat" radio signal, and they want to use it to find the missing half of the universe's matter. The mysterious signal is a fast radio burst called “FRB 20220610A”. It was found 8,000,000,000 years into the universe's past, its light rhythmically pulsing from the heart of three merging galaxies.
------------------------- 4284 - RADIO WAVE BURSTS
- This the biggest
radio-wave explosion ever found could be used to weigh the universe. Astronomers have traced a mysterious radio
source to three merging galaxies 8 billion light-years away. Studying it could
help uncover the universe's missing matter.
Much of the universe is made of of matter that we can't see.
-
- As the fast radio
burst (FRB) is 1.5 times more ancient and distant than the previous record
holder, its light could be used to find an approximate weight to the
universe. Maybe even learn where half of
its matter went.
-
- If we count up the
amount of “normal matter” in the Universe, the atoms that we are all made of,
we find that more than half of what should be there today is missing. We think that the missing matter is hiding in
the space between galaxies, but it may just be so hot and diffuse that it's
impossible to see using normal techniques.
-
- Currently, there
are two ways to approximate the matter contained within our universe. The first
uses “gravitational lensing” to see how much matter warps the path of light
from distant galaxies through space; and the second looks at the universe's
first light from the “cosmic microwave background” remnant radiation from the
Big Bang that can reveal where matter clumped together at the dawn of the
universe and how it evolved over time.
-
- The problem is
that these methods disagree, creating a discrepancy called the “Sigma-8
tension” that threatens to tear standard theories of cosmology apart. Where the
missing matter could be isn't certain, but astronomers have a hunch it is
floating in intergalactic space in vast, diffuse clouds of gas and dust. But to
measure these clouds, astronomers need powerful sources of light.
-
- Fast radio bursts
are discharging more energy in a few milliseconds than the sun does in a year.
Astronomers have long puzzled over the source of these sudden, bright flashes.
But because FRBs erupt predominantly from galaxies millions or billions of
light-years away, and flare quickly, scientists have struggled to pin them
down.
-
- One known source
of FRBs is a “radio pulsar” or a “magnetar”, a highly magnetized,
rapidly-rotating husk of a dead star. Equipped with unusually strong magnetic
fields that are trillions of times more powerful than Earth's, the dead stars
spin in space, sweeping out beams of intense radio waves from their poles like
giant lighthouses.
-
- As FRB pulses move
through space, the matter they move through separates out the light pulse’s
different frequencies, producing a lag between the arrival of the high and low
frequencies in the signal. From the length of this delay, astronomers can
figure out how much matter the burst has moved through.
-
- The fascinating
patterns of 35 repeating fast radio bursts (FRBs) reveal new properties of
these mysterious blasts of deep-space radiation that appear and disappear in
milliseconds.
-
- Astronomers
watched 35 explosive outbursts from a rare repeating "fast radio
burst" as it shifted in frequency like a "cosmic slide whistle,"
blinking in a puzzling pattern never seen before. These millisecond-long flashes of light from
beyond the Milky Way are capable of producing as much energy in a few seconds
as the sun does in a year.
-
- FRBs are
believed to come from powerful objects like neutron stars with intense magnetic
fields, also called magnetars, or from cataclysmic events like stellar
collisions or the collapse of neutron stars to form black holes. Complicating
the FRB picture, a few FRBs are "repeaters" that flash from the same
spot in the sky more than once, while the majority burst once and then vanish.
-
- The SETI
Institute's Allen Telescope Array (ATA) was used to study the highly active
repeating FRB known as “FRB 20220912A”.
As they watched the FRB over 541 hours (nearly 23 days), the team saw
its bursts of radiation cover a wide range of frequencies in the radio wave
region of the electromagnetic spectrum, which eventually developed into a fascinating pattern that
astronomers had never seen before.
-
- This work provides
both confirmation of known FRB properties and the discovery of some new
ones. The bursts of radiation from FRB
20220912A shifted down in frequency, and when converted to notes played on a
xylophone, this shift sounded like a slide whistle's descending toot, a
behavior that scientists had never seen before from an FRB.
-
- This also helped
the team identify that there is a cutoff point for the brightness of bursts
from FRB 20220912A, revealing how much of the overall cosmic signal rate this
FRB is responsible for.
-
- This work proves
that new telescopes with unique capabilities, like the ATA, can provide a new
angle on outstanding mysteries in FRB science.
-
-
December 23, 2023
RADIO WAVE BURSTS 4284
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Wednesday, December 27, 2023 ---------------------------------
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