Tianlai experiment
{{Short description|A Chinese radio astronomy experiment aimed for observing neutral hydrogen and detecting dark energy}}
The Tianlai experiment ({{lang-zh|s=天籁}}) is a radio astronomy experiment run by the National Astronomical Observatories, Chinese Academy of Sciences (NAOC).Chen, Xuelei. "Radio detection of dark energy—the Tianlai project." Scientia Sinica Physica, Mechanica & Astronomica 41.12 (2011): 1358.CHEN, Xuelei, "THE TIANLAI PROJECT: A 21CM COSMOLOGY EXPERIMENT", International Journal of Modern Physics: Conference SeriesVol. 12, pp. 256-263 (2012) https://www.worldscientific.com/doi/abs/10.1142/S2010194512006459 Its aim is to develop the key techniques of intensity mapping observation for the redshifted 21cm line of neutral hydrogen, in order to probe the large-scale structure, and to detect and measure the dark energy using baryon acoustic oscillations (BAO). The experiment is currently at a pathfinder stage, two pathfinder interferometric imaging radio telescope arrays have been built for this experiment. These are the cylinder array and the dish array. In the full scale stage, the experiment is expected to measure the large scale structure, and use the BAO feature to detect the dark energy Xu, Yidong; Wang, Xin; Chen, Xuelei, Forecasts on the Dark Energy and Primordial Non-Gaussianity Observations with the Tianlai Cylinder Array, The Astrophysical Journal, Volume 798, Issue 1, article id. 40, 10 pp. (2015). https://arxiv.org/pdf/1410.7794.pdf
History
The "Key Technologies of Radio Detection of Dark Energy" research is funded in 2012. The NAOC team decided to choose this site in 2014, after surveying many sites in China.Wu, Fengquan, et al. "Site selection for the Tianlai experiment proceedings of the XXXIst URSI general assembly and scientific symposium to be held in Beijing, China (CIE), August 17–23, 2014." 2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS). IEEE, 2014. The first full observation took place in 2016.Das, Santanu, et al. "Progress in the construction and testing of the Tianlai radio interferometers." Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX. Vol. 10708. SPIE, 2018. https://arxiv.org/pdf/1806.04698.pdf Between 2020 and 2022, new digital backends are installed on both the dish array and cylinder array, enable them to search for fast radio burst.Yu, Zijie; Deng, Furen; Niu, Chenhui; Li, Jixia; Sun, Shijie; Wang, Weiyang; Wang, Yougang; Wu, Fengquan; Chen, Xuelei, Detection of a bright FRB with the Tianlai Cylinder Pathfinder Array https://www.astronomerstelegram.org/?read=15342Yu, Zijie; Deng, Furen; Niu, Chenhui; Li, Jixia; Sun, Shijie; Wang, Weiyang; Wang, Yougang; Wu, Fengquan; Chen, Xuelei, Detection of FRB 20220912A at 750 MHz with the Tianlai Dish Pathfinder Array https://www.astronomerstelegram.org/?read=15342
Location
The Tianlai arrays are located at (91°48′ E, 44°09′ N), the signal collected by these arrays are transmitted via optical fiber to the station house, which is about 6 km away in the Hongliuxia village of the Balikun County, Xinjiang, China.{{citation needed|date=June 2023}}
Status and plan
Cylinder Array: This includes three adjacent, north-south oriented parabolic cylinder reflectors, with dimension of 15 meter wide and 40 meter long. However, only the central section of about 12.4 meters of each cylinder are used at present. A total of 96 dual polarization feed units are installed, with 31, 32 and 33 respectively on the three cylinders, all with the same total length, but with spacing of 41.33 cm, 40 cm, 38.75 cm respectively.Li, J., Zuo, S., Wu, F. et al. The Tianlai Cylinder Pathfinder array: System functions and basic performance analysis. Sci. China Phys. Mech. Astron. 63, 129862 (2020). https://doi.org/10.1007/s11433-020-1594-8 This unequal spacing is designed to reduce grating lobes of the array
Zhang, Jiao, et al. "Sky reconstruction for the Tianlai cylinder array." Research in Astronomy and Astrophysics 16.10 (2016): 158. https://iopscience.iop.org/article/10.1088/1674-4527/16/10/158/pdf
The arrays are planned to carry out HI surveys and cross correlate with optical observations.Perdereau, Olivier; Ansari, Réza; Stebbins, Albert; Timbie, Peter T.; Chen, Xuelei search by orcid; Wu, Fengquan; Li, Jixia; Marriner, John P.; Tucker, Gregory S.; Cong, Yanping; Das, Santanu search by orcid; Li, Yichao; Liu, Yingfeng search by orcid; Magneville, Christophe; Peterson, Jeffrey B.; Phan, Anh; Robinthal, Lily; Sun, Shijie; Wang, Yougang search by orcid; Wu, Yanlin; Xu, Yidong search by orcid; Yu, Kaifeng; Yu, Zijie; Zhang, Jiao; Zhang, Juyong; Zuo, Shifan, The Tianlai dish array low-z surveys forecasts,
Monthly Notices of the Royal Astronomical Society, Volume 517, Issue 3, pp.4637-4655, https://doi.org/10.1093/mnras/stac2832
International collaboration
The Tianlai international collaboration have members from the US, France, and India. It has a weekly online meeting, and an annual collaboration meeting{{cite web | url=https://tianlai.bao.ac.cn/gallery.html | title=Tianlai Project | Gallery }}
Name
The word "Tianlai" literally means "heavenly sound" in Chinese. It is a concept which was first used by the ancient Chinese philosopher Zhuang Zhou, to mean a hidden rhythm of the nature. It is also often used to describe beautiful music. Here it refers to the acoustic oscillation of the Early UniverseChen, Xuelei. "The Tianlai Project: A 21-cm Intensity Mapping Experiment." AAPPS Bulletin 25.5 (2015). https://web.s.ebscohost.com/abstract?direct=true&profile=ehost&scope=site&authtype=crawler&jrnl=02182203&AN=110040725&h=Ut%2b%2fIIvd8QHAEUc9jYyS1zJXCJd4HGresJP5ps8xj817fYMgPPzewLzd6wwi7eydK%2fXNTMzD4os4XwSdki8oGQ%3d%3d&crl=c&resultNs=AdminWebAuth&resultLocal=ErrCrlNotAuth&crlhashurl=login.aspx%3fdirect%3dtrue%26profile%3dehost%26scope%3dsite%26authtype%3dcrawler%26jrnl%3d02182203%26AN%3d110040725
References
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{{{91°48′E, 44°09′N}|China}}
Category:Astronomical observatories in China
Category:Research institutes of the Chinese Academy of Sciences