There are two kinds of
matter in the universe. There is dark matter, which is invisible to us. It is
known only because of its gravitational effects on a grand scale. And there is
ordinary matter, which we are all familiar with; it makes up gases, dust,
stars, planets, and earthly things like cake batter and camping gear.
Scientists have
estimated that ordinary matter makes up only 15% of all matter. But they have
struggled to document where all of the matter is located, since only about half
of it is accounted for. Now, with the help of powerful bursts of radio waves
emanating from 69 locations in the cosmos, researchers have found the “missing”
matter.
It was primarily hiding
as thinly distributed gas spread out in the vast expanses between galaxies and
was detected because of the effect the matter has on the radio waves traveling
through space. This tenuous gas is the intergalactic medium, a sort of fog
between galaxies.
Scientists had
previously determined the total amount of ordinary matter using a calculation
involving light observed that was left over from the Big Bang. But they could
not actually find half of this matter.
Researchers found that
a smaller slice of the missing matter resides in the halos of diffuse material
surrounding galaxies, including our Milky Way.
Ordinary matter is
composed of baryons, which are the subatomic particles needed by protons and
neutrons to build atoms. Dark matter, on the other hand, is a mysterious
substance. Scientists do not know what new particle or substance makes up dark
matter.
How did so much
ordinary matter end up in the middle of nowhere? Vast amounts of gas are
ejected from galaxies when massive stars explode as supernovas of when
supermassive black holes inside galaxies “burp,” expelling material after
consuming stars or gas.
If the universe were a
more boring place, or the laws of physics were different, ordinary matter would
all fall into galaxies, cool down and form stars until every proton and neutron
were a part of a star.
Thus, these violent
processes throw ordinary matter across immense distances and consign it to the
cosmic wilderness. This gas is not in its usual state; it is in the form of
plasma, with its electrons and protons separated.
The missing ordinary
matter was detected and measured by using phenomena called fast radio bursts,
or FRBs. These are powerful pulses of radio waves emanating from faraway points
in the universe. Their exact cause remains mysterious, but a leading hypothesis
is that they are produced by highly magnetized neutron stars, which are compact
stellar embers left over after a massive star dies in a supernova explosion.
As light in the radio
wave frequencies travels from the source to Earth, it becomes dispersed into
different wavelengths, just like a prism turns sunlight into a rainbow. The
degree of dispersion depends on how much matter is in the light’s path. This
provides the mechanism for pinpointing and measuring matter where it otherwise
would remain unfound.
Scientists used radio
waves traveling from 69 FRBs. Of these, 39 were discovered using a network of
110 telescopes located at Caltech’s Owens Valley Radio Observatory near Bishop,
California, which is called the Deep Synoptic Array. The remaining 30 FRBs were
discovered using other telescopes.
The FRBs were located
at distances up to 9.1 billion light-years from Earth, which is the farthest of
these on record. A light-year is the distance light travels in a year (5.9
trillion miles/9.5 trillion km).
With all the ordinary
matter accounted for, researchers were able to determine its distribution.
About 76% resides in intergalactic space, approximately 15% in galaxy halos,
with the remaining 9% concentrated within galaxies as stars or gas.
Now they can move on to
other mysteries regarding ordinary matter. And beyond that, they still don’t
know the nature of dark matter.
https://www.msn.com/en-us/news/technology/astronomers-locate-universe-s-missing-matter/ar-AA1GPaMp?ocid=hpmsn&cvid=c615a1d5e8e948159c93cc31030732f0&ei=41
