A brief history of China's involvement with the SKAO
The Ministry of Science and Technology of China (MOST) started to take part in the pre-construction phase of the SKA project in September 2012 on behalf of the Chinese government. China was then involved in the international negotiations to establish the SKAO as an intergovernmental organisation and was one of the signatories of the SKAO Convention at a ceremony in Rome in March 2019. In April 2021, the Standing Committee of the National People’s Congress ratified the Convention and in June 2021, China became a full member of the SKAO Council.
Under the leadership of MOST, the National Remote Sensing Centre of China (NRSCC) has been hosting the SKA China Office, responsible for managing the National SKA Programme of China to deliver on China’s commitments to the SKAO, taking part in the governance of the Observatory, delivering the agreed contributions and organising and coordinating SKA-related research and development activities.
Chinese industry and the science community in the country have taken part in the engineering design and development work of several SKA international design consortia, including leading the Dish consortium, and the early research work of multiple SKA science working groups.
China SKA Development Report (China SKA White Paper)
In August 2021, China held a critical meeting to review the country’s involvement in the project in the past decade. Following that meeting, a report was published detailing the development of China’s participation in the SKA project going forward, including the guiding principle and policy measures necessary to organise and coordinate the Chinese community to take part in the SKAO. This marked the start of a new phase of the country’s involvement in the Observatory.
The report starts with an introduction of Chinese government’s guiding principles to take part in the project, and is followed by a detailed explanation of China's participation in the project in terms of science objectives, engineering technology and talent development. The report also lists the policies and measures for implementation.
Chinese SKA Science Projects
After an extensive evaluation and review over past decade, ten projects have been selected by the Chinese SKA community as the priority SKA science cases, including the detection of epoch of reionization, testing gravity with pulsars, detection of nanoherts gravitational waves with pulsar timing, FRBs, etcs. Toward achieving these ambitious science goals with the future SKA telescopes, a dedicated state funding scheme has recently been established and will be secured before the operation of the SKA telescopes to refine the science projects and maintain a sustainable development of science teams.
1. Deep Imaging of the Eoch of Reionization
With its unprecedentedly high sensitivity and angular resolution, SKA1-low will be the unique radio telescope in the world for tomographic imaging of the ionized structures in the epoch of reionization (EoR). The Chinese EoR team, led by Dr. Cathie Zheng at Shanghai Astronomical Observatory, will focus on a deep observation of 1000 hours integration time in one targeted area of 20 square degrees in frequency range of 100-200 MHz. A number of state-of-art techniques and algorithms will be developed to control and reduce various systematic errors such as inaccurate calibration, instrument artifacts, poor sky modeling, confusion limits, etc.
2. Pulsar Searching, Timing and Testing Fundamental Laws of Physics
The high sensitivity observations of pulsars including searching and timing with SKA1 will enable us to test the fundamental laws of electromagnetic, weak, strong, and gravitational interactions under extreme physical condition. In particular, a routine observation of pulsar time array with SKA can help to build the nanohertz gravitational wave observatory. The Chinese pulsar team, led by Dr. Kejia Lee in Peking University, will demonstrate the feasibility with Chinese SKA pathfinder FAST before the operation of SKA1.
3. Neutral Hydrogen Survey and Cosmology
The high precision observation of neutral hydrogen (HI) by the SKA1-mid telescope will map the large scale structures, providing key information for the resolution of fundamental problems in modern cosmology, including the nature of dark energy and dark matter, the origin of the Universe, as well as gaining new insights on galaxy formation and evolution. The Chinese cosmology team will test the key techniques of HI galaxy and intensity mapping observation and calibration by using the Chinese SKA pathfinder Tianlai experiment, and develop new methods and algorithms of HI data analysis before the delivery of SKA1.
4. Cosmic Magnetic Field
The broadband polarization survey with SKA1 will obtain rotation measures of 2-3 million extragalactic sources, which will enable us to understand the cosmic magnetic fields of pc to Mpc scales. The Chinese comic magnetic field research team will focus on the magnetic fields in the Milky Way Galaxy, AGNs and cosmic large-scale structures by using polarization observations from FAST and other SKA pathfinders, and aim to construct the 3D picture of magnetic fields in the Universe with SKA1 and future full SKA.
5. The Milky Way and Interstellar Medium
The high sensitivity and resolution of SKA will enable us to map the Milky Way in unprecedented details in both emission and absorption, by tracing neutral hydrogen clouds, star formation regions, HII regions, and supernova remnants. The Chinese ISM team will further study the life cycle of the interstellar medium: how diffuse atomic clouds evolve to molecular clouds, to stars, and finally to remnants of dead stars.
6. Bursts in the Universe
Our research with SKA1 will target on precisely localizing the numerous fast radio bursts (FRRs), and then use FRBS to map out the plasma content along their propagation path, trace the cosmic evolutionary history, and probe fundamental physical processes under strong gravity/magnetic field, or even new physics. Thanks to its unprecedentedly high sensitivity, SKA1 will greatly help extend the detection horizon of FRBs. The feasibility of detecting high-redshift FRBs will be demonstrated using the Chinese SKA pathfinder FAST in advance.
7. Active Galactic Nuclei (AGN) Feedback and Black Hole
The Chinese research team will make use of the high sensitivity and angular resolution of SKA1 to observe outflows launched from low-luminosity AGNs and their interaction with the interstellar medium in the host galaxies, and neutral hydrogen in galaxies with various AGN activity. The latter includes the total mass, spatial distribution, and velocity field. Combining observations and numerical simulations, the Chinese team will be able to significantly deepen our understanding of the role of AGN feedback played in galaxy evolution.
8. Galaxy dynamics and galaxy evolution
For the first time, SKA1 will be able to provide neutral hydrogen images with high spatial resolutions comparable to that of optical telescopes. The Chinese research team will make use of SKA1 and its pathfinders to conduct deep neutral hydrogen imaging observations of a large sample of galaxies in order to systematically study the distribution and dynamic structures of cold gas in different types of galaxies, understand the effects of environments on galaxy evolution, provide observational constraints on galaxy evolution models, and reveal the role of neutral hydrogen in formation and evolution of galaxies.
9. Origin of life
SKA1-low1 would provide an unprecedented opportunity to investigate the origin of life (OoL). The Chinese OoL team will quantify the physical and chemical conditions of the site for OoL through numerical simulations and experimental studies, and assess the feasibility of FAST as the pathfinder of SKA1 in detecting exoplanet magnetic field and searching for signals from extraterrestrial intelligence.
10. Origin of ultra-high-energy cosmic rays
The SKA1-low will provide a unique opportunity to study cosmic rays (CR) with high precision using radio measurements, allowing us to address the puzzling problem of the transition from Galactic to extragalactic CRs. The Chinese CR team has been carried out a prototype experiment for the radio detection of high-energy CRs such as GRAND, developing algorithms for identifying and reconstructing inclined air showers induced by CRs. The team will also search for Askaryan radio pulses with FAST, which can be one of the most challenging projects for SKA.
Since 2013, a dozen Chinese universities, companies and research institutes have taken part in the engineering design and development work of seven international design consortia, including Dish (DSH), Low-Frequency Aperture Array (LFAA), Mid-Frequency Aperture Array (MFAA), Science Data Processor (SDP), Signal and Data Transport (SaDT), Wideband Single Pixel Feeds (WBSPF) and Phase Array Feeds (PAF). This allowed the community to deepen and broaden their expertise in a number of keay areas, relevant beyond the astronomy sector.
In the construction phase, Chinese industry will lead the construction of the SKA Dish structures and will contribute to the development of other new technologies used in the SKA project, such as signal processing, frequency synchronization and science data processing.
Pathfinder Telescope: FAST
The Five-hundred-meter Aperture Spherical radio Telescope (FAST), located in a karst depression in Guizhou, is the world’s largest single-dish radio telescope, with a receiving area equivalent to 30 football fields. Its scientific goals include:
- Detect neutral hydrogen to the edge of the universe, reconstruct the images of the early universe;
- Discover pulsar, establish a pulsar timing array, and participate in pulsar navigation and gravitational wave detection in the future;
- Join the International Very-Long-Baseline Interferometry Network to obtain hyperfine structures of celestial bodies;
- Perform high resolution radio spectral survey. Detect weak space signals;
- Participate in the search for extraterrestrial intelligence.
- Case Study – Forming the next generation of astronomers through SKA Summer Schools
SKA summer schools have been organised in several SKAO member states to equip university students studying astrophysics and related fields with skills in key areas. These schools are helping students become skilled researchers in a competitive international research landscape, ensuring they get access to SKA precursor and pathfinder facilities and eventually the SKA telescopes.
In China, such week-long training sessions have been running roughly annually since 2013 with the support of the Ministry of Science and Technology, the SKA China Office, and the Chinese Academy of Sciences, attracting about 100 students and junior researchers from across the country each time.
Since 2013, a total of over 700 students, with a number from remote provinces, have benefitted from such training, being taught the basics about radio astronomy and SKA as well as skills including data processing, imaging and VLBI. Some students have gone on to become successful researchers themselves, taking part in National SKA Program of China and leading major science cases.
In 2021 the first hybrid school saw a total of 50 students on site and more than 200 online, both domestic and overseas, from 56 higher education institutions, practice VLBI data processing, imaging and calibration techniques using SKA related demo software systems.
- Case Study – 2019 SKA Shanghai Meeting
At the end of November, some 250 engineers and scientists from around the globe gathered in the city of Shanghai, China for a momentous occasion: after six years of hard work, the sixth and final all-hands meeting on SKA engineering design was held, shortly before the full SKA system review was due to take place.
Co-hosted by the SKA Organisation and China’s Ministry of Science and Technology, the four-day meeting was attended by experts from 19 countries, including those working at precursor, pathfinder and peer facilities.
Traditionally focused on engineering and design, the meeting’s scope extended beyond engineering. As the design phase of was coming to an end, engineers, scientists, policymakers and other experts attending the meeting took the opportunity to take a look ahead, discussing procurement, commissioning, and operations of the SKA telescopes. Find out more here: Final SKA Engineering Design Meeting Kicks Off in Shanghai