We might have finally seen dark matter
What's the story
A recent study has claimed to provide the first direct evidence of dark matter, a mysterious and invisible substance that is believed to make up 27% of the universe. The research was led by Professor Tomonori Totani from the University of Tokyo, who found gamma rays emanating from the center of our Milky Way galaxy. The discovery could be a major breakthrough in understanding this elusive cosmic component.
Cosmic enigma
Dark matter: A century-old cosmic mystery
The concept of dark matter was first introduced in the 1930s by Swiss astronomer Fritz Zwicky. He observed that distant galaxies were rotating faster than their mass would allow, leading to the hypothesis of this invisible substance. Dark matter doesn't emit or absorb light but has an unseen gravitational effect on surrounding galaxies. Despite searches using ground-based detectors, space telescopes, and machines like the Large Hadron Collider near Geneva, no direct evidence of dark matter particles has been found yet.
Particle hypothesis
The WIMP theory and gamma-ray detection
One theory suggests that dark matter is made up of weakly interacting massive particles (WIMPs). These are heavier than protons but interact very little with normal matter. When two WIMPs collide, they can annihilate each other and release other particles along with a burst of gamma rays. To look for possible dark matter signals, Prof. Totani analyzed data from NASA's Fermi Gamma-ray Space Telescope, which detects the most energetic photons in the electromagnetic spectrum.
Potential discovery
Gamma rays hint at dark matter's presence
Totani found a pattern of gamma rays that seemed to match the shape of the dark matter halo extending from the center of our galaxy. If confirmed, this would indicate that dark matter is made up of elementary particles 500 times more massive than protons. However, further research is needed to rule out any other astrophysical processes or background emissions that could explain these signals.
Caution advised
Further research needed for confirmation
Professor Totani stressed that the "decisive factor" would be detecting the gamma rays with the same spectrum from other regions of space, like dwarf galaxies. However, Professor Justin Read from the University of Surrey noted that the absence of significant signals from such galaxies argues against Totani having seen gamma rays emitted from dark matter particle annihilation. The study has been published in the Journal of Cosmology and Astroparticle Physics.