First Polarization Image around the Black Hole Shadow
The polarized light at the vicinity of the black hole for the first time (EHT Collaboration et al. 2021, ApJL, 910, L12), which carries the magnetic field and plasma information very close to the black hole.
The maximum linear polarization fraction reaches up to ~15%, and the net azimuthal linear polarization pattern may result from organized, poloidal magnetic fields. In addition, through the general relativistic magnetohydrodynamic (GRMHD) simulations, we infer the mass accretion rate onto the black hole in M87 as (3-20) x 10^-4 Mo/yr (EHT Collaboration et al. 2021, ApJL, 910, L13).