The black hole imaging research team at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences has pursued its goals tirelessly toward the sea of stars, securing a place at the forefront of global black hole research——

　　"Dialogue" with the Universe, Freezing Black Holes in Frame

　　What kind of mysterious existence is a black hole, really? Thanks to one photograph after another, humanity's understanding of it has been gradually made concrete——

　　In April 2019, the first-ever image of a black hole captured by the Event Horizon Telescope (EHT)——the image of the supermassive black hole at the center of the M87 galaxy——was released, stunning the world;

　　Three years later, the first image of the black hole at the center of the Milky Way, also captured by the EHT, was released, verifying Einstein's general theory of relativity from the perspective of a strong gravitational field;

　　Less than a year after that, an international research team captured for the first time a "panoramic image" of the M87 black hole, freezing the black hole shadow, accretion disk, and jet simultaneously in a single photograph.

　　These three iconic photographs trace the growth of the black hole imaging research team at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, from active participation to securing a place at the forefront of global black hole research. "Astronomy is undoubtedly romantic, but researchers spend most of their time quietly cultivating their work over the long term," said Shen Zhiqiang, director of the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, describing this team that looks up at the stars.

　　Breaking the Research "Ceiling"

　　In 1997, Shen Zhiqiang completed his doctorate. "Seeing" black holes clearly seemed to hold an endless attraction for him. "At that time, we had to wait 20 months just to get 5 hours of observation time."

　　Over the following five years, he and his colleagues carried out more than 20 high-resolution VLBI (Very Long Baseline Interferometry) observations, and every step of the work represented the ** progress in the field at the time. In 2005, Shen Zhiqiang led an international astronomy research group in publishing the world's first high-resolution image of the Milky Way's central black hole at an observation wavelength of 3.5 millimeters in the journal Nature.

　　"I returned to China because I wanted to push domestic black hole imaging research to an internationally advanced level." Throughout his studies, Lu Rusen always kept in mind the aspiration of his advisor, Shen Zhiqiang. In 2018, bringing years of research accumulation with him, he returned to China and joined the Department of Radio Astronomy Science and Technology at the Shanghai Astronomical Observatory.

　　"Science requires debate; existing research 'ceilings' need to be broken, and more importantly, a 'Chinese voice' must be heard." Lu Rusen was filled with drive, and building on the observatory's existing research foundation, he focused on conducting research in the internationally most cutting-edge 1-millimeter wavelength imaging.

　　In 2023, he led an international team in completing imaging research on the M87 black hole and its surrounding environment, capturing a photograph of the black hole in a new wavelength band for the first time and achieving a breakthrough in taking a "panoramic image" of the "central engine" of an active galactic nucleus. After the research results were published in the journal Nature, they attracted widespread attention worldwide.

　　"Expensive" Computation

　　To see a black hole from Earth, one must use telescopes operating in the submillimeter band, and submillimeter astronomical observations require dry weather conditions and a thin atmosphere. As a result, a dormant volcanic crater in Hawaii has become a holy site for astronomical observation.

　　Jiang Wu, an associate researcher in the Department of Radio Astronomy Science and Technology at the Shanghai Astronomical Observatory, had the opportunity to go to the site and participate in the Event Horizon Telescope observations. "Apart from the shortness of breath and slight headache caused by altitude sickness, what impressed me most was that although we were observing in the middle of the night, everyone was full of enthusiasm and meticulous in their work," Jiang Wu recalled. Sometimes, on the way back to base in the early morning, he would see sparks emerging from other craters and be deeply awed by the power of nature.

　　Zhao Shanshan is a post-90s young researcher in the High-Resolution Radio Astrophysics Research Group at the Shanghai Astronomical Observatory. Her theoretical working group needs to compare the model image library with observational data and select the optimal model.

　　The environment around a black hole is extremely complex, which leads to uncertainty in many physical parameters. Behind every model image lies a massive amount of manpower and computing power. A single numerical simulation requires weeks to months of computation on a supercomputer, and if parameters change, it must be recalculated. "From this perspective, the theoretical interpretation of black hole images is very 'expensive,'" Zhao Shanshan said.

　　Making a "Movie" of a Black Hole

　　"In the past, I thought doing research meant sitting in front of a computer deriving formulas and writing code. I never imagined I could also participate in building a telescope." In order to use China's own equipment to photograph black holes as soon as possible, Zhao Shanshan followed the team to Tibet to conduct surveys and look for a suitable site.

　　"To seize the high ground in the next step of research—making a 'movie' of a black hole—and to gain more international academic discourse power, we must have our own observation equipment." Lu Rusen is well aware that there is still a long way to go. To this end, the Shanghai Astronomical Observatory has promoted the construction of China's millimeter-wave VLBI experimental system, actively advanced the construction of submillimeter-wave telescopes and arrays in the western region, and developed related observation facilities.

　　Jiang Wu is also working hard to advance the construction of submillimeter-wave telescopes. "Multi-frequency simultaneous reception technology is the development trend of the future. It can detect weaker signals, which will hopefully allow us to observe more black hole images."

　　"The public is very interested in our research results and always asks many questions. At such times, I truly feel that exploring the unknown is human nature." Zhao Shanshan stated that as a "vanguard" in exploring black holes, bringing the ** scientific research results to the public is a responsibility and an obligation, and she also gains the joy of sharing through these exchanges.