Contributing to a Range of Research and Development by Observing Light, Emitted When Air Absorbs Gamma Rays Coming from the Universe
Fujitsu delivered a Cherenkov Telescope Array (CTA) controller system that can observe with a level of sensitivity nearly 10 times that of existing gamma ray telescopes to the Institute for Cosmic Ray Research (ICRR), University of Tokyo,
While ancient astronomy only studied visible light, present-day astronomy also covers long wavelength radio waves and short wavelength gamma rays. Observing a wide range of electromagnetic waves in addition to visible light makes it possible to explore the Universe more deeply.
It is said that gamma rays bring knowledge regarding the origin and evolution of the Universe because they radiate straight from sources.
Although most gamma rays coming from space are blocked by the atmosphere, light known as Cherenkov light is emitted when gamma rays hit the atmosphere. Cherenkov light spreads in the direction of incoming gamma rays, in a cone shape. Managing several Cherenkov telescopes in an integrated manner and performing analysis enables a more accurate, sensitive observation to be carried out.
Such astronomical facilities are being developed in a joint effort between 33 countries around the world. The one that is now under construction is known as the CTA project. To observe such light flashes accurately, the influence of artificial light must be eliminated and telescopes must be installed at a high altitude near the outer atmosphere where Cherenkov light occurs.
CTA will be constructed at the summit of a 2,200-meter high mountain on La Palma, one of Spain's Canary Islands in the northern hemisphere (northern site), and in the desert of Paranal, Chile, in the southern hemisphere (southern site) in order to observe the entire sky. The construction of the northern site is now underway. CTA will be partially operating within this year and fully operating, including the southern site, in 2025.
Analyzing Images of Cherenkov Light with 57 Servers. Fujitsu Servers Work Reliably in Harsh Environments
The CTA northern site consists of four large-aperture telescopes (LST: 23 meters in diameter) and five medium-aperture telescopes (MST: 12 meters in diameter) (to be expanded to 15 MSTs in the future). As the name Cherenkov Telescope Array suggests, it analyzes images with a combination of telescopes that observe Cherenkov light, thereby increasing sensitivity and accuracy.
Unifying images from several telescopes requires a tremendous amount of computational power. The Fujitsu system that we delivered this time batch processes all observation data obtained at the CTA northern site. High rates of data are stored in a high-capacity storage server with an effective capacity of 3 PB and are then processed by 57 servers (which deliver 61 TFLOPS of performance with 1,824 cores). This makes it possible to analyze doses of incoming gamma rays and estimate their directions and energy in real time.
Apart from performance, another key point is that this system also enables stable, continuous operation even under severe conditions unique to uplands, including large temperature fluctuations between day and night.
CTA is an international joint project, for which Japan is working as CTA-Japan. Japan is mainly contributing in the areas of optics and image analysis and the Fujitsu system plays a crucial role of undertaking all image processing for the northern site.
Fujitsu has provided controller systems for massive radio telescopes, optical-infrared telescopes and neutrino observation to research institutions and other organizations before. With the new addition of CTA controller system, we will continue to leverage ICT and contribute to resolving mysteries of the Universe that have not been unraveled.