X-ray light pulses out in rings from a neutron star in the Circinus X-1 star system.
Credit: NASA's Chandra X-ray Observatory
SDSU astrophysicist Fridolin Weber will present his research on “Big Bang matter” at this year’s Albert W. Johnson lecture.
Every atom in every molecule of your body was born in a single
spectacular, 2000-billion-degree Kelvin explosion some 13.8 billion
years ago. But the Big Bang also produced exotic forms of matter that
lasted only fleeting seconds before blinking out of existence. Fridolin Weber
searches the universe for these elusive particles that can only exist
in extreme astronomical conditions, such as inside the hearts of
super-dense neutron stars. The San Diego State University theoretical
astrophysicist will present findings from his galactic hunt on Friday,
April 7, at the annual Albert W. Johnson Lecture.
“It’s kind of mind-boggling. If things had happened just a little differently in the early universe, we wouldn’t be here.”
Weber’s quarry is the quark, an elementary particle that constitutes
matter’s most fundamental building block. Quarks are bound up in
composite particles like protons and neutrons and are generally not
found in nature by themselves. The exception is inside neutron stars,
which are incredibly dense remnants of massive stars blown apart by
supernova explosions. Composed primarily of neutrons, they are only 24
kilometers (15 miles) or so in diameter, yet are twice as massive as our
sun.
That amount of mass packed into a relatively miniscule
area creates extraordinary density at the star’s core, squeezing atomic
nuclei so tightly that fundamental particles like quarks can exist
freely. It’s the closest parallel to conditions immediately after the
Big Bang that we know of in our universe.
“We want to understand
what happened in the moments and minutes after that gigantic
explosion,” Weber said. “We turn to neutron stars to see if we can
detect the astrophysical signature of this ‘Big Bang matter.’”
Weber
and his colleagues trawl data from enormous radio telescopes scattered
around the world. They’re looking for distortions in radio waves emitted
by stars that are characteristic of neutron stars’ unusually high
temperatures. Right now, astrophysicists know of about 2,000 neutron
stars in the sky, but Weber expects that number to grow to more than
30,000 in the coming years as telescopes and computing technology
improve.
Just because you’ve found a neutron star doesn’t mean
you’ve found quarks, though. Once a good candidate is located, Weber
looks for a secondary pattern.
A neutron star is a magnetically
charged sphere that radiates energy over time, causing it to “spin
down,” like a spinning figure skater with outstretched arms. At the same
time, the star is becoming denser and denser. Finally, the theory goes,
the density will become so great that the atomic nuclei within the
star’s core will break apart, forming quarks. This briefly makes the
star “spin up” again—the figure skater pulling in her arms—before the
quarks dissipate and the star resumes spinning down. Astrophysicists
like Weber can detect this “spin down, spin up, then spin down again”
pattern, allowing them to indirectly rewind the universe to its very
beginning.
“These quarks would exist as plasma, which would have existed in the first couple of minutes after the Big Bang,” he said.
It’s
easy to get lost in the fine-grained data and details needed to study
complex astrophysics, but when Weber steps back from all that and
considers the connection every single molecule in the universe shares
with that single celestial moment, he’s humbled.
“It’s kind of
mind-boggling,” he said. “If things had happened just a little
differently in the early universe, we wouldn’t be here."
Weber’s
lecture, “Searching for Big Bang Matter in Stars,” will take place at 3
p.m. on Friday in Storm Hall West, Room 11. For more information, visit
the Albert W. Johnson University Research Lectureship website.