BEIJING, 30 November (BelTA - Xinhua) - China's Dark Matter Particle Explorer (DAMPE) has detected unexpected and mysterious signals in its measurement of high-energy cosmic rays, which might bring scientists a step closer to shedding light on invisible dark matter.
The satellite, also called Wukong, or Monkey King, has measured more than 3.5 billion cosmic ray particles with the highest energy up to 100 tera-electron-volts (TeV for short, corresponding to 1 trillion times the energy of visible light), including 20 million electrons and positrons, with unprecedentedly high energy resolution.
"DAMPE has opened a new window for observing the high-energy universe, unveiling new physical phenomena beyond our current understanding," said Chang Jin, chief scientist of DAMPE and vice director of the Purple Mountain Observatory of the Chinese Academy of Sciences (CAS).
"This is the first time a space experiment has reported a detailed and precise electron and positron spectrum up to about 5 TeV. In this energy range, we found some unexpected and interesting features. We have detected a spectral break at 0.9 TeV and a possible spike at 1.4 TeV," said Chang.
Dark matter, which cannot be seen or touched, is one of the great mysteries of science. Scientists calculate that normal matter, such as galaxies, stars, trees, rocks and atoms, accounts for only about 5 percent of the universe. However, about 26.8 percent of the universe is dark matter and 68.3 percent dark energy.
China sent DAMPE into an orbit of about 500 kilometers above the earth on December 17, 2015, to look for evidence of the annihilation or decay of dark matter particles in space.
DAMPE has the widest energy range coverage and the highest energy resolution of all the dark matter probes currently in space. Based on the satellite's data, scientists drew the cosmic ray electron and positron spectrum.
Fan Yizhong, deputy chief designer of the scientific application system of DAMPE, said, "The spike at 1.4 TeV on the spectrum is very unusual. The signals might have originated from either dark matter or pulsars. Even if they were from pulsars, it would be quite a strange astrophysical phenomenon that nobody had known before."
"However, the data of the strange signal are still not enough. We need to collect more data to make sure it's real," Chang said.
Researchers have ruled out the possibility that the unusual signals are caused by a malfunction of the satellite's detectors. Independent analyses from five different teams all came to the same conclusion, said Chang.
