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Taiwan major contributor to black hole image: institute

2019/04/11 19:59:48

Academia Sinica President James C. Liao (廖俊智, center)

Taipei, April 11 (CNA) Taiwan made a significant contribution to an international astronomical project to capture the world's first image of a black hole, as it not only supported operation of radio telescopes synchronized to capture the image but also helped analyze relevant information obtained, Academia Sinica has said.

The country's top research institution has been involved in the operation of the telescopes in Hawaii -- the Submillimeter Array (SMA) and the James Clerk Maxwell Telescope (JCMT) -- along with the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile, said Academia Sinica President James C. Liao (廖俊智).

"Taiwan has played a substantial role in this groundbreaking finding," Liao said.

The three telescopes, along with five counterparts across the world, were given credit for successfully fulfilling the main mission of the Event Horizon Telescope (EHT) observing campaign, established in 2017 to capture images of a black hole.

The project name "event horizon" means the boundary of a black hole, the institute said.

The five other telescopes are the Atacama Pathfinder Experiment (APEX), the IRAM 30-meter telescope, the Large Millimeter Telescope Alfonso Serrano, the Submillimeter Telescope, and the South Pole Telescope, Liao said.

About 30 Academia Sinica scientists, together with 200 experts from 12 other research institutes worldwide, eventually identified and captured the image of the black hole, which is located 55 million light-years from Earth and has a mass 6.5-billion times that of the Sun, according to the institute.

The image of the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster, was taken in April 2017, showing the first direct visual evidence of a supermassive black hole and its shadow, said Keiichi Asada, an EHT project member and associate research fellow at Academia Sinica.

Multiple calibration and imaging methods were used to reveal a ring-like structure with a dark central region -- the black hole's shadow -- that persisted over seven consecutive days of observation, Asada explained.

Black holes are extraordinary cosmic objects with enormous masses but extremely compact sizes, he said, adding that the presence of these objects affects their environment in extreme ways, warping spacetime and super-heating any surrounding material.

"If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow -- something predicted by Einstein's general theory of relativity that we've never seen before," explained chair of the EHT Science Council Heino Falcke of Radboud University, the Netherlands.

"This shadow, caused by the gravitational bending and capture of light by the event horizon, reveals a lot about the nature of these fascinating objects and allowed us to measure the enormous mass of M87's black hole," he said.

Meanwhile, a supermassive black hole is the largest type of black hole, containing a mass that is hundreds of thousands to billions of times greater than that of the Sun.

The image captured is the result of years of international collaboration, which offers scientists a new way to study the most extreme objects in the Universe predicted by Einstein's theory of general relativity during the centennial year of the historic experiment that first confirmed the theory, according to Academia Sinica.

"This (photo) is a pioneering find in the study of black hole astro-physics," Asada said, explaining that the EHT observations use a technique called very-long-baseline interferometry (VLBI), which synchronizes telescope facilities around the world and exploits the rotation of the planet to form one huge, Earth-size telescope observing at a wavelength of 1.3mm.

VLBI allows the EHT to achieve an angular resolution of 20 micro-arcseconds -- enough to read a newspaper in New York from a sidewalk café in Paris, Academia Sinica said.

Taiwan also leads the Greenland Telescope project, through Academia Sinica in collaboration with the United States' Harvard-Smithsonian Center for Astrophysics (CfA) and that was incorporated into the EHT last year. It is expected that with more telescopes on board, it could soon be possible to produce an image of a black hole shadow that has 10 times the resolution of the current results, the institute said.

"We are currently studying how to move the telescope to the Greenland Summit, and how to construct the telescope site at the Summit," explained Chen Ming-tang (陳明堂), an Academia research fellow and one of the leading scientists in EHT.

Relocation to the summit, which is 3,200 meters above sea level, could help the telescope work better since the atmosphere is thinner and there is less water vapor content, which is greatly beneficial for higher frequency observations, Chen said.

Moving the telescope is the next step for Taiwan, in conjunction with Danish scientists in an effort to contribute to the EHT program, he said.

(By Lee Hsin-Yin)
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