Unlocking the Mystery: Why Dark Matter Remains Stable and What It Means for Our Universe

The quest to understand Dark Matter is still on. For over sixty years, researchers have observed and studied this mysterious substance, which makes up about 85% of the Universe’s mass. While no one has pinpointed the exact particle yet, recent studies are shedding light on its nature. For example, a team from Tokyo Metropolitan University, led by Associate Professor Wen Yin, has developed a new method to estimate how long Dark Matter lasts, moving us closer to solving this puzzle.

Wen Yin worked with researchers from various institutions, including Kyoto Sangyo University and the National Astronomical Observatory of Japan. Their findings were published in the journal Physical Review Letters.

The concept of Dark Matter first appeared in relation to Einstein’s Theory of General Relativity. This theory explains how mass influences the shape of spacetime. However, when scientists observed distant galaxies, they found that their spinning speeds didn’t match the mass that we could see. This mismatch suggested that there must be hidden mass, or Dark Matter, that we cannot detect with our eyes.

Scientists define Dark Matter as a type of mass that only interacts with regular matter through gravity, not through other forces. This makes it hard to study, as researchers aren’t sure exactly what Dark Matter is. Potential candidates include weakly interacting massive particles (WIMPs) and axion-like particles (ALPs). Recent research has used a mix of models and observations to learn more about Dark Matter’s properties.

In their latest study, Yin’s team used the 6.5-meter Magellan Clay Telescope in Chile. They focused on two dwarf galaxies, Leo V and Tucana II, to look for signs of ALPs. These particles are theorized to decay and emit light in the near-infrared spectrum. However, observing this light is tricky due to noise from sources like zodiacal light and interstellar dust.

To tackle this challenge, the team employed a new technique targeting a specific decay process that produces radiation in a narrow band. They used the WINERED instrument on the Magellan Telescope to gather precise data from the dwarf galaxies.

The results showed no signs of decay, allowing the researchers to establish the upper limits on how often these decay events happen. They estimated that the lifetime of ALPs could be between ten million and a hundred million times the current age of the Universe. This sets a new record for the lifespan of Dark Matter and offers exciting leads for future research.

The investigation into Dark Matter is far from over. With new methods and tools, scientists are slowly unraveling its secrets.