演講資訊

摘要：

The first ever image of the black hole in M87, showing an asymmetric ring-like structure, was observed with the Event Horizon Telescope (EHT) in April 2017, and was published about two years ago. The black hole image in polarized light has been recently published by the EHT Collaboration (EHTC). The resolved fractional linear polarization has a maximum located in the southwest part of the ring, where it rises to the level of ~15%. The polarization position angles are arranged in a nearly azimuthal pattern. The EHTC compared a number of images constructed from general relativistic hydrodynamic (GRMHD) simulations with the observation and was able to put a tight constraint on the physical properties of the plasma in the vicinity of the black hole. Also, the inferred magnetic field structure is consistent with a picture where there is a strong, ordered, poloidal magnetic field in the vicinity of the black hole. This magnetic field can regulate the mass accretion process, and can play a critical role in launching powerful jets. I will briefly overview the observation, data calibration and analysis, and physical interpretation of the results.