In the past ten years, astrophysics provides some of the most visible scientific breakthroughs. From the identification of super-massive black hole at the center of the Milky Way to the establishment of accurate cosmology, from the discovery of exoplanets to the detection of gravitational wave signal from the merger of compact objects, over and over again, our Universe proves that it is indeed the final frontier of physical exploration. In the next decade, a series of ground-based and space imaging surveys will, once again, reshape the landscape of astrophysics and cosmology.
Together, these surveys will provide increasingly deep images with much improved spatial and temporal resolution that will depict an unprecedentedly profound and vivid Universe. Meanwhile, such a large dataset also brings numerous challenges to astrophysical research. One of the most outstanding challenges is the lack of sufficient spectroscopic follow-up capability on the ground. The spectrum of an object is its beacon in the cosmic flow, the fingerprint of its physical nature, and the password toward understanding its origin. Only through spectroscopic observation can we generate a 3-dimension map of our Universe, estimate the age of a remote galaxy, analysis the chemical composition of a nearby star, measure the accretion of a super-massive black-hole, and identify the nature of a rare transient object.
Since 2000, the Sloan Digital Sky Survey (SDSS) has repeatedly demonstrated the unlimited scientific potential of large-scale "spectroscopic census." The Galactic survey performed by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has presented us with the largest-ever spectroscopic database of Milky Way stars. Moreover, the ongoing survey of the Dark Energy Spectroscopic Instrument will constrain our cosmological model using the baryon acoustic oscillations (BAO) signature with unparalleled accuracy. However, despite these efforts, future goals of astrophysics and cosmology put forward much more demanding requirements for the next generation spectroscopic survey: large aperture telescope becomes.
The MUltiplexed Survey Telescope (MUST) is born to tackle these challenges. Under the current design, the first-generation survey instrument of MUST will excel in the pursue of a wide range of unique missions, including but not limited to:
- Map the distributions of galaxies to higher redshift and smaller physical scale. Taking advantage of such a detailed 3D map, we will study the distribution of dark matter and interrogate the nature of dark energy.
- Investigate the rising and fall of star formation in galaxies in the last 10 Gyrs, understand the star-formation and mass-assembly history of different populations of galaxies.
- Utilize the galaxies within galaxy clusters or groups to portray the most massive dark matter halos in our Universe and use this unique cosmological probe to trace the evolution of dark energy and exam the theory of gravity.
- Provides the most complete and thorough high-resolution spectroscopic census of our neighbors in the Milky Way. Establish a detailed chemical and kinematic archive to facilitate the search of Earth 2.0.
- Observe an unprecedented large sample of stars in the Milky Way's stellar halo or satellite dwarf galaxies to reconstruct our own Galaxy's early history and probe the nature of dark matter through its small scale structure.
- Measure the accretion rate and mass of super-massive black holes (SMBHs) in a galaxy sample that is one order of magnitude larger than the existing one. Improve our understanding of the growth of SMBH and its impact on galaxy evolution.
- Efficiently confirm and follow-up the rare and valuable transient targets such as the electromagnetic counterparts of gravitational wave events, the tidal disruption events, and the high-redshift Type Ia supernovae.