Dark matter and dark energy have been likened by scientists to "two dark clouds in the physical sky of the 21st century." Dark matter has both "through the wall" and "invisibility", which is not only invisible to the human eye, but also can not be captured by astronomical telescopes and electromagnetic means. To explore them, more advanced observation equipment and more sophisticated experimental techniques are needed.
The Wide-Field Survey Telescope (MUST) project was born. Recently, the "fifth generation Wide Field spectral survey telescope key technology design verification and development" project launch and implementation plan demonstration meeting was held in Jiangyin, Jiangsu Province. Tsinghua University, leading the top astronomical units within and outside the United Nations, will deploy the world's first new-generation spectral survey telescope.
So, what exactly is the configuration of MUST? What are its characteristics compared with other superior telescopes at home and abroad? How will it observe dark matter and solve its mysteries?
Archaeology on the Galactic Frontier
Industry experts believe that the current discovery of cosmology and the future exploration of dark energy and dark matter, the fifth generation of wide-field spectral survey telescope is urgently needed.
Astronomy is an extremely equipment-dependent discipline, and the performance of the telescope largely determines the level of research. The designed MUST optical aperture is up to 6.5 meters, and it can simultaneously observe the medium and high resolution spectra of at least 20,000 objects, covering a wide spectral range of 0.36-1.0 microns. Within a decade, MUST is expected to make major fundamental and original breakthroughs in cutting-edge areas such as dark energy, dark matter, gravitational wave cosmology, and galaxy formation.
CAI Zheng, project manager of MUST and deputy director of the Department of Astronomy at Tsinghua University, told Science and Technology Daily that in the Milky Way and neighboring universe, the star spectral survey conducted by MUST will help people carry out "archaeological" research on the "frontier" of the Milky Way, reveal the history of the formation of stars in the Milky Way, and conduct a more detailed "census" of the galaxy group.
Specifically, the core scientific goal of MUST is to obtain more accurate cosmological models to explore the evolution of dark energy and the nature of dark matter. It will conduct a high-redshift large-scale structure cosmological survey to better explore the origin and evolution of dark energy, the era of cosmic inflation, and the mass of neutrinos.
At the same time, MUST will also use galaxy surveys to better characterize the physical relationship between galaxies and dark matter halos, and explore the nature of dark matter through different observational probes. MUST will also conduct an unprecedented large-scale survey of galaxies and black holes to help better understand galaxy formation in different environments, the co-evolution of galaxy-supermassive black holes, and obtain a physical picture of the cosmic ecosystem.
CAI Zheng said that compared with the telescopes that have been built at home and abroad, MUST has the characteristics of large aperture, large field of view, high spectral resolution and high efficiency in dark matter research. As the fifth generation spectral survey telescope, it can observe more celestial bodies at the same time, improving observation efficiency and scientific output.
"MUST, when completed, will be the last unfinished piece of the puzzle for a medium-sized ground-based telescope. "Compared with the world's highest performance telescope, its comprehensive sky survey capability will be increased by more than 10 times, and it is expected to achieve world-class results." CAI Zheng said.
Characterizing the dynamic universe in new dimensions
MUST's optical system has superior imaging quality, like bright "big eyes" probing deep space. How will it work?
According to Huang Song, MUST project scientist, MUST will measure the spectrum of galaxies with high redshift on the cosmological scale for the first time through the redshift survey of galaxies and quasars on a very large scale, and obtain the three-dimensional structure of the early universe.
In addition, it will conduct small-scale and flexible spectral surveys to obtain more accurate galaxy-dark matter halo physical correlation models, improve the constraints of the small-scale structure of the nearby universe on the nature of dark matter, provide high-precision redshift data support for supernova cosmology and gravitational lensing cosmology, and explore new cosmological constraints, including local velocity surveys. To better realize the mission of the fifth generation of cosmological spectral survey telescope.
The superior performance of MUST will also support richer and more flexible scientific exploration, such as advancing the observational study of galaxy formation and evolution, and building more accurate models of the structure and evolution of the Milky Way. In addition, it can assist in time domain astronomy, opening up the spectral time domain as a new observational parameter space, and discovering unknown new areas of physics.
"MUST is a large scientific device and platform that meets the strategic needs of national basic science development, meets the requirements of the fifth generation of cosmological spectral survey, is expected to produce breakthrough results on a series of major key scientific issues, and can systematically continue to carry out strategic, forward-looking and comprehensive research, and will strive to carry out the first large-scale time domain spectral survey."
This will not only depict the dynamic universe in new dimensions, but will also enhance synergies with other multi-form deep space exploration projects." Guo Liquan, head of mechanical system of MUST project, introduced.
The reporter learned that the reason why MUST can effectively carry out the fifth phase of the cosmological spectral survey is because researchers have broken through a series of key technical problems. According to Guo Liquan, the researchers solved the contradiction between wide band coverage, high energy utilization, and medium and high spectral resolution by designing a multi-channel spectrometer.
At the same time, the band is divided into multiple channels by a chromatic mirror, and each channel is independently designed with dispersion elements, spectral imaging and photodetectors. The dispersion elements are designed with the latest transmission gratings or ion beam etched gratings and custom-designed according to the shining wavelength and spectral resolution requirements of each channel to achieve the highest grating diffraction efficiency in a compact spatial structure. The integrated design of the project solves the problem of system installation and testing in high altitude areas.The first light is expected in 2030
"It is expected that the first light will be achieved by 2030." "It is expected to make significant progress in cosmological research and the observation of dark matter and dark energy," said Huang Lei, director of the Institute of Laser and Photon Technology at Tsinghua University's Department of Precision Instrumentation and chief engineer of the MUST project.
Huang Lei analysis, MUST both multi-target spectrum and imaging spectrum two functions, is the world's largest spectral survey telescope, its powerful spectrum acquisition ability will have a profound impact on the basic parameters of cosmology, the universe's primary inflation, the nature of dark matter, dark energy evolution, time domain astronomy (such as gravitational wave electromagnetic counterpart), galaxy formation, exoplanets and extraterrestrial life and other fields. These scientific problems are the major problems in astronomy and physics at present, and they are also problems that the international astronomical community is striving to solve, and may be solved in the next 10-20 years.
In addition, the spectral measurement of the radial velocity of the stars in the Milky Way by MUST can improve the measurement accuracy of the distribution of dark matter in the local universe, and also contribute to a better understanding of the physical phenomena generated by dark matter at small scales.
Specifically, the Milky Way Disk Star Survey conducted by MUST gives high-precision measurements of the density and velocity distribution of dark matter in the Milky Way near our solar system. At the same time, the radial velocity survey of the large number of galactic halo stars located at the galactic boundary can further help to measure the shape of the galactic halo and give a more accurate limit on the total dark matter halo mass of the Milky Way.
Huang Lei said that considering the flexibility and durability of the MUST spectral survey, it is expected to become a powerful "dark matter observatory", obtain a large amount of dark matter related data, and together with other different types of dark matter experiments and observations, in the next 20 years to make an important contribution to the answer to the question "what is dark matter?"
