MAY 09, 2019 6:20 AM PDT

Astronomers Baffled by the Strange Glow at the Center of Milky Way

Gamma-ray radiation is assigned with false purple color in this image of the galactic center (NASA/FGST)Since 2009, astrophysicists have been puzzled about an excess of gamma ray appearing at the center of the Milky Way. The next decade witnessed a dramatic "tug of war" between two competing hypotheses that were proposed to explain this bizarre phenomenon.

The story started back in 2009, when cosmologist Dan Hooper at the University of Chicago first saw a mysterious gamma-ray glow at the center of the Milky Way, based on analyses conducted on the images captured by NASA’s Fermi Gamma-ray Space Telescope. The telescope is on board of a spacecraft launched in 2008 into low Earth orbit, in order to perform gamma ray astronomy observations. Hooper and his co-worker thought that the "aura" was the result of dark matter annihilation

Dark matter is an elusive entity that is believed to make up 27% of the universe's matter-energy continuum (in contrast, normal matter only constitutes 5%) and capable of bending the paths of stars with its gravitational pull. Astronomers have long suspected that our galaxy sits inside a giant pool of dark matter.

Fermi Gamma-ray Space Telescope (NASA)According to the hypothesis of Hooper and his student, dark matter should also be capable of colliding with each other and releasing high-energy photonic particles such as gamma ray, which contradicts with the commonly accepted idea that they interact exclusively through gravitational force. While some agreed with the dark mattter explanation, others looked somewhere else for answers.

In 2015, two studies reexamined the data from Fermi telescopes and found graininess within the glow. If dark matter was behind the massive gamma ray at the galactic center, the spread of photonic energy should have appeared even without any bright spots. Therefore, the authors behind these two works suggested that instead, a large population of pulsars is likely the cause of the glow.

First discovered by astrophysicist Jocelyn Bell Burnell, pulsars are highly magnetized, dying stars with ten times or more the mass of our sun. They emit an intensive pulse of electromagnetic radiation, with an interval ranging from milliseconds to seconds.

Just as the pulsar theory was gaining momentum and the dark matter theory slowly slipped away, the debate took a bewildering turn: the authors in one of the 2015 studies walked back their earlier conclusion: a flawed technique they used in the study might have misidentified dark matter as pulsars.

What's more, a recent report from the International Space Station’s Alpha Magnetic Spectrometer experiment gave the dark matter theory a leg-up: the levels of antiprotons in the galactic center, an indication of the remnant of dark matter collisions, is higher than expected.

This finding not only puts the dark matter theory in a more advantageou spot, but also is seen by some as the first indirect prove of dark matter.

Hints of Dark Matter from Milky Way's Center Revealed by Gamma-Ray Map (Space.com)

Source: the Daily Galaxy

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
NOV 21, 2019
Chemistry & Physics
NOV 21, 2019
Pharmacist Who Debunked False Vit C Claim Honored by the Maddox Prize
"Sense about Science" is a UK-based NGO that promotes the public understanding of science. Every year the organization gives the John Maddox Priz...
NOV 22, 2019
Chemistry & Physics
NOV 22, 2019
Scientists Observed the Root Cause of Lithium Batteries Failures in Real Time
Lithium batteries have high energy storage capacity, but sometimes they have unexpected failures and can even cause a fire. A team of scientists at the Dep...
DEC 12, 2019
Chemistry & Physics
DEC 12, 2019
Self-learning, Light-responsive Robot Inspired by Pavlov's Dog
Russian physiologist Ivan Pavlov famously trained the canines in his experiments to salivate in response to the sound of a metronome, which was a showcase...
DEC 30, 2019
Chemistry & Physics
DEC 30, 2019
New Cobalt-free Electrochemistry to "Clean Up" Battery Manufacturing Practice
The rise of portable devices and electric vehicles (EVs) are changing the way we live and work. But the use of lithium-ion batteries, which are essential f...
JAN 26, 2020
Space & Astronomy
JAN 26, 2020
How Much Do You Know About the Planet Mercury?
Mercury is the solar system’s smallest planet, and it’s also the one residing closest to the Sun. But while Mercury is commonly shrugged off as...
FEB 10, 2020
Space & Astronomy
FEB 10, 2020
Learn How NASA Suppresses the Loud Sounds of a Rocket Launch
When a large chemical rocket’s engines ignite, they produce thousands, if not millions, of pounds of thrust. This much power is necessary to loft the...
Loading Comments...