Imaging the Accretion Zone in M87
Kravchenko et al. report on high angular resolution polarimetric observations of the nearby radio galaxy M87 using the VLBA at 24 GHz (λ = 1.3 cm) and 43 GHz (λ = 7 mm) in 2017–2018. New images of the linear polarization substructure in the nuclear region are presented, characterized by a two-component pattern of polarized intensity and smooth rotation of the polarization plane around the 43 GHz core. From a comparison with an analogous dataset from 2007, the authors find that this global polarization pattern remains stable over a time interval of 11 years, while showing smaller month-scale variability. The authors discuss the possible Faraday rotation toward the M87 nucleus at centimeter to millimeter wavelengths. These results can be interpreted in a scenario where the observed polarimetric pattern is associated with the magnetic structure in the confining magnetohydrodynamic wind, which also serves as the source of the observed Faraday rotation.
Figure caption: VLBA images at 43 GHz (left) and 24 GHz (right) of the polarized (color) and total (gray contours) intensity from M87, plus observed position angles.
Publication: E. Kravchenko (Istituto di Radioastronomia, Lebedev Physical Institute) et al., Linear polarization in the nucleus of M87 at 7 mm and 1.3 cm, Astronomy & Astrophysics, 637, L6 (May 2020).
