A groundbreaking new study has shed light on the rapid spin of the supermassive black hole at the center of our galaxy, known as Sagittarius A* (Sgr A*). This discovery, made possible by NASA’s Chandra X-ray Observatory and the NSF’s Very Large Array, has provided valuable insights into the behavior of black holes and their impact on the surrounding spacetime.
The study, led by Ruth Daly of Penn State University, utilized a new method called the “outflow method” to determine the spin of Sgr A*. By analyzing X-ray and radio data and combining it with an independent estimate of the black hole’s mass, the researchers were able to constrain its spin. The results revealed that Sgr A* is spinning at an astonishingly high rate, warping the spacetime around it and giving it the shape of an American football.
Black holes possess two fundamental properties: their mass and their spin. Understanding these properties is crucial in unraveling the mysteries of these cosmic phenomena. Previous estimates of Sgr A*’s rotation speed have varied greatly, with some suggesting that it is not spinning at all, while others proposed it is rotating close to the maximum rate. This new study, however, provides compelling evidence that Sgr A* is indeed spinning rapidly.
The implications of this discovery are significant. A black hole’s spin can generate powerful outflows, such as jets, which require the presence of matter in its vicinity. Sgr A*, due to limited fuel, has been relatively quiet in recent millennia with weak jets. However, if the amount of material surrounding Sgr A* increases, as suggested by this study, it could lead to a surge in activity and more powerful jets.
The artist’s illustration accompanying the study depicts Sgr A* as a cross-section with gas swirling around it in a disk. The black sphere at the center represents the event horizon, beyond which nothing can escape, not even light. Looking at the spinning black hole from the side, the surrounding spacetime takes on the shape of a football, with the degree of flattening depending on the speed of rotation. The yellow-orange material represents the swirling gas, which eventually plunges towards the black hole and crosses the event horizon.
The study’s findings have far-reaching implications for our understanding of black holes and their role in shaping the universe. By unraveling the mysteries of Sgr A*’s spin, scientists can gain valuable insights into the behavior and energy production of supermassive black holes. As we continue to explore the cosmos, studies like this bring us closer to unlocking the secrets of these enigmatic cosmic entities.
The research team behind this groundbreaking study includes Biny Sebastian from the University of Manitoba, Megan Donahue from Michigan State University, Christopher O’Dea from the University of Manitoba, Daryl Haggard from McGill University, and Anan Lu, also from McGill University.
The results of this study, published in the January 2024 issue of the Monthly Notices of the Royal Astronomical Society, mark a significant milestone in our understanding of supermassive black holes. With further advancements in technology and continued research, we can expect even more fascinating discoveries that will reshape our understanding of the universe and our place within it.
NASA’s Marshall Space Flight Center manages the Chandra program, while the Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations and flight operations. These institutions play a crucial role in enabling groundbreaking studies like this one, pushing the boundaries of human knowledge and expanding our horizons in the vast expanse of space.
