Recent observations from the High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory have transformed our understanding of cosmic radiation, revealing that powerful gamma rays can originate from microquasars within our galaxy.
Traditionally, astronomers believed that such high-energy radiation was exclusive to distant quasars, fueled by supermassive black holes. However, the microquasar V4641 Sagittarii, located approximately 20,000 light-years away in the Sagittarius constellation, has been identified as a source of gamma rays with photon energies reaching up to 200 teraelectronvolts (TeV).
This discovery challenges established theories, as it was previously assumed that only supermassive black holes could generate such intense radiation. V4641 Sagittarii, a compact system consisting of a massive star and a black hole, has demonstrated that even smaller systems can produce comparable gamma rays.
The HAWC observatory, situated in Mexico, employs an array of 300 large water tanks to detect cosmic particles. When high-energy particles traverse the water, they emit Cherenkov radiation, which is then analyzed to determine the energy and source of incoming cosmic rays.
Notably, the jet from V4641 Sagittarii is oriented directly toward Earth, creating a phenomenon known as superluminal motion, where parts of the jet appear to move faster than light. Although this does not violate the laws of physics, it provides researchers with a unique opportunity to study these high-energy jets without the distortions associated with vast cosmic distances.
Dr. Sabrina Casanova from the Institute of Nuclear Physics of the Polish Academy of Sciences, who led the study, pointed out that V4641 Sagittarii is not alone. Other microquasars, observed by facilities like LHAASO in China, are also showing signs of emitting very high-energy photons. This suggests that microquasars could play a significant role in cosmic ray production within our galaxy.
This breakthrough opens new avenues for research, allowing scientists to investigate cosmic radiation processes in real-time. The relatively undisturbed radiation from nearby microquasars enables a clearer understanding of the physics governing high-energy jets, enhancing our grasp of how these phenomena influence the structure and evolution of galaxies.