Chinese scientists built a neutrino telescope 3,500 meters below the sea. What can they see?

Xinhua News Agency, Shanghai, January 8 (Reporters Dong Xue and Pan Xu) How do people understand the universe? In addition to visible light, there are also mysterious neutrinos. They hardly react with matter and can escape from dense celestial environments. They are a powerful tool for studying the extreme universe.

Xu Donglian, Tsung-Dao Lee Scholar at the Tsung-Dao Lee Institute of Shanghai Jiao Tong University and chief scientist of the project, said that the team is building a super-powerful neutrino telescope, Sea Bell, on the seabed to capture high-energy neutrinos to answer unsolved mysteries such as the origin of cosmic rays.

Academician Jing Yipeng, the project leader of the Hailing Telescope, introduces the project (Photo taken on October 10, 2023). Photo by Xinhua News Agency reporter Liu Ying

As a subatomic particle second only to photons in number, the birth of neutrinos is often related to extreme events in the universe, such as the Big Bang, supernova explosions, the merger of binary neutron stars, black hole explosions, etc. Among them, high-energy neutrinos mainly come from the collision of cosmic rays with dust and gas.

Xu Donglian introduced that the Hailing Telescope project will be launched at the end of 2022 and is expected to be completed around 2030. It is located in a deep-sea plain about 3.5 kilometers deep near the equator in my country's waters, with a diameter of about 4 kilometers and an area of ​​about 12 square kilometers. It consists of 1,200 cables and has a design life of 20 years.

Conceptual image of the Sea Bell Project. The array is arranged in a Penrose tessellation geometry, with about 1,200 vertical cables, each with about 20 optical modules, located about 3,500 meters below the ocean, with a monitoring volume of (4 x 4 x 0.5) cubic kilometers

Image source: Tsung-Dao Lee Institute, Shanghai Jiao Tong University

According to the design, these cables are anchored vertically on the seabed like giant seaweed, each about 700 meters long and 70 to 110 meters apart. Each cable carries about 20 optical detection spherical cabins, like a string of bells in the deep sea, waiting for the arrival of high-energy neutrinos.

It is worth mentioning that the way the Hailing Telescope "looks up" at the universe is different. It does not "look up" but "looks down". "The Hailing Telescope will use the entire earth as a shield to capture high-energy neutrinos penetrating from the opposite side of the earth, and realize 360-degree full-sky detection through the rotation of the earth," said Xu Donglian.

The team expects that within one year after the completion of the Sea Bell Telescope, it will be able to discover a stable neutrino source in the barred spiral galaxy NGC 1068 in the constellation Cetus, and discover neutrino bursts similar to the flare body TXS 0506+056. The black hole of this active galaxy is covered by a large amount of dust, and even high-energy photons cannot escape, but neutrinos escape.

Jing Yipeng, an academician of the Chinese Academy of Sciences and the project leader of the Heilongjiang Telescope, said that my country has a layout in multi-band telescopes, space gravitational wave and low-energy neutrino observatories. The Heilongjiang High-Energy Neutrino Telescope will fill an important gap in my country's multi-messenger astronomical observation network and promote and improve the construction of my country's multi-messenger astronomical observation network.