Chinese scientists want to build a powerful telescope to find dark matter
- The ambitious project – known as VLAST – aims to achieve 10 times the sensitivity of Nasa’s Fermi Large Area Telescope
- Researchers say it could go into orbit by the end of this decade, but it still needs government approval
Chinese scientists want to build a next-generation space observatory that could put them in a leading position in the search for dark matter – if it works out.
The ambitious Very Large Area gamma-ray Space Telescope, or VLAST, is still in the early research and development phase. But the aim is to achieve 10 times the sensitivity of Nasa’s Fermi Large Area Telescope – currently the most sensitive gamma-ray telescope in the world.
The telescope could go into orbit by the end of this decade if it gets the green light from the Chinese government soon, according to researchers involved in the proposal to build it.
Gamma rays are the highest-energy form of light. They help scientists to see into the extreme universe to observe things like rapidly spinning neutron stars and super dense black holes. They are also indirect proof of dark matter, which makes up most of the matter in the cosmos but has eluded scientists for decades.
Astronomers believe that dark matter must exist to provide the gravitational pull needed to hold galaxies and galaxy clusters together. Hypothetically, when dark matter particles collide they decay or annihilate each other, and at the same time produce gamma rays which can be detected by telescopes.
To look for traces of dark matter particles, VLAST will monitor the cosmic gamma-ray spectrum between 0.3 giga-electron volts and 20 tera-electron volts with unprecedented energy resolution, the researchers said in a paper outlining the plan, published in the Chinese journal Acta Astronomica Sinica on May 26.
They said VLAST would also zoom in on our galactic centre to examine a puzzling surplus of gamma-ray radiation, which could be explained with the presence of self-annihilating dark matter.
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The paper was written by researchers from the Purple Mountain Observatory in Nanjing, the University of Science and Technology of China in Hefei, and the Institute of Modern Physics in Lanzhou.
Aside from the hunt for dark matter, the scientists also plan to use VLAST to explore hot topics in high-energy astronomy – including gamma-ray bursts, X-ray binary stars, and the origin of cosmic rays.
Based on its preliminary design, VLAST will consist of three types of detectors. They would first distinguish gamma-ray photons from other particles coming into the telescope, and then precisely measure the energy and trajectory of the gamma-ray photons.
The detectors are expected to have a combined weight of 16 tonnes – much heavier than an average space telescope.
“We would need a Long March 5 rocket to send it into orbit,” the paper’s lead author, Fan Yizhong from the Purple Mountain Observatory, said in an online talk in October.
The team has been working to develop key technologies for the project. “From electronics to the detectors and the satellite platform, it’s been really challenging,” Fan said during the talk, organised by the International Space Science Institute in Beijing.
“We’ll need at least 10 years to get ready – if the government decides to fund us.”
The researchers submitted their VLAST proposal to the Chinese Academy of Sciences in March and are awaiting a decision, according to the paper.
Chinese satellite ‘breakthrough’ in search for dark matter
Scientists around the world have been searching for dark matter in three ways: indirect detection; creating dark matter particles in a powerful particle collider like the Large Hadron Collider in Europe; and direct detection, such as through the PandaX experiment in an underground laboratory in China.
On the indirect detection path, China’s first dark matter probe, the Dark Matter Particle Explorer – also known as Wukong or the Monkey King – has been operating in low-Earth orbit for more than six years.
A collaboration between China, Switzerland and Italy – led by researchers from the Purple Mountain Observatory – its results include detecting a spectral break at around 0.9 tera-electron volts, which helped shed light on the annihilation or decay of dark matter particles.
