The China Space Station Telescope (CSST), also known as Xuntian, is a next generation space observatory due for launch this year. It’s designed to operate alongside China’s Tiangong space station but will function completely independently in orbit, occasionally docking for maintenance and upgrades. It has a 2 meter aperture mirror, five instruments and is only slightly smaller than the Hubble Space Telescope but has a field of view 17500 deg, that’s 300 times larger than Hubble. Due to its larger field of view and high resolution, it will be able to study large scale structure of the cosmos while Hubble was far better at studying individual galaxies, stars and planets.
The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis (Credit : NASA)
In a recent paper published by Yan Gong from Chinese Academy of Sciences and team, they examine CSST’s capabilities for exploring the properties of dark energy and dark, modified gravity theories, and other key cosmological topics. They plan to achieve this by measuring the Universe’s dark matter distribution and expansion history through observations of weak gravitational lensing, galaxy clusters, type Ia supernovae (SNe Ia), and baryonic acoustic oscillations (BAO – regular, periodic fluctuations in the density of visible baryonic matter.)
Galaxy cluster Abell 2218 and its gravitational lenses. This image was taken by Hubble in 1999 (Credit : NASA)
The analysis of the capabilities of CSST against the teams objectives shows that they will be able to measure dark energy’s equation of state (a mathematical description of how dark energy behaves as the universe expands) with better than 5% accuracy, potentially reaching ~1%. This precision can determine whether dark energy is simply the cosmological constant or something that evolves dynamically, like a scalar field. It will also be able to distinguish between cold or warm dark matter and precisely measure dark matter particle mass (such as axions), which will help laboratory efforts to detect dark matter particles.
CSST is expected to be able to make significant advances in a number of cosmological investigations in addition to its analysis of dark matter. Other areas for study include strong gravitational lensing events, two-dimensional BAO measurements and the Alcock-Paczynski effect which is an illusion affecting the determination of the depth of galaxy clusters using redshift measurements and an incorrect value for Hubble’s constant.
The influence of dark matter across the Cosmos
The telescope will also work with other advanced instruments, such as Europe’s Euclid telescope, future Cosmic Microwave Background experiments, time-domain telescopes that detect transient phenomena, radio telescopes like FAST and MeerKAT for 21cm signal detection. With numerous advanced instruments scheduled to begin operations in the coming years, the field of cosmology looks set for an era of discovery and breakthrough.
Source : Future Cosmology: New Physics and Opportunity from the China Space Station Telescope (CSST)