Dark matter is one of the greatest mysteries in the universe.

Scientists believe it makes up most of the mass in the cosmos, yet they have never seen it directly.

A new study led by Associate Professor Wen Yin from Tokyo Metropolitan University has used advanced technology to take a fresh look at dark matter, setting new limits on how long it can exist before it decays.

Their findings, published in Physical Review Letters, bring us closer to understanding this invisible substance.

What is dark matter?

For over a century, astronomers have noticed something strange: galaxies spin faster than expected, as if hidden mass is pulling them together.

This unseen material is called dark matter. Scientists suspect it exists, but they don’t know exactly what it is made of or how to detect it.

One idea is that dark matter particles might slowly decay over time, giving off faint light. If researchers can spot this light, they might be able to confirm the existence of dark matter.

How scientists looked for dark matter decay

Professor Yin’s team observed two distant galaxies, Leo V and Tucana II, using the Magellan Clay Telescope in Chile.

They focused on the near-infrared part of the light spectrum because some dark matter models predict that decaying dark matter would emit light in this range.

However, detecting this faint signal is difficult because infrared light is filled with “noise” from other sources, such as:

• Zodiacal light – sunlight scattering off dust in space.
• Atmospheric glow – light from Earth’s atmosphere heated by the Sun.

To overcome this challenge, the team used a special spectrograph called WINERED, which can separate light from dark matter decay from background light. This high-precision tool allowed them to analyze the infrared light with great accuracy.

What they found

After four hours of observation, the team did not detect any dark matter decay signals. While this might seem disappointing, it actually helped set new limits on dark matter’s lifetime.

Their data suggests that if axion-like particles (a possible dark matter candidate) exist, they last at least 10 to the power of 25 to 26 seconds—that’s 10 to 100 million times the age of the universe!

This study not only sets the most precise limit yet on dark matter’s lifetime but also shows how new infrared technology can help in the search for this elusive substance.

Even though dark matter remains undiscovered, small anomalies in the data hint that more research could lead to actual detection in the future.

The hunt for dark matter continues, and with more observations and improved techniques, we may soon uncover the missing piece of our universe.

Source: KSR.