Kinematics of the nucleus of the radio galaxy M 87

Abstract

The superfine structure of the active region of the radio galaxy M 87 has been investigated at millimeter and centimeter wavelengths. A disk, a core, a jet, and a counterjet have been identified. The disk is inclined to the plane of the sky at an angle of 60◦ toward the jet. We show that the surrounding thermal plasma inflows onto the disk, is transferred in a spiral to the center, and is ejected, carrying away an excess angular momentum as it is accumulated. The remainder falls to the forming central massive body. The temperature of the plasma as it is transferred increases to relativistic values; the ejection velocity increases to 0.02c. The nozzle diameter decreases as the axis is approached. The central high-velocity bipolar outflow is surrounded by low-velocity components, tubes. The interaction of the rotating flow with the ambient medium collimates and accelerates the flows. Ring currents whose tangential directions are observed as parallel chains of components are generated in the flows. The ring currents of the disk and jets produce aligned magnetic fields. The ejection of the jet and counterjet plasma flows is equiprobable; the motion is along the field in one case and opposite to the field in the other case, causing an acceleration or deceleration. The velocity of the high-velocity jet is a factor of 1.7 higher than the counterjet velocity. The acceleration compensates for the losses of relativistic electrons observed at distances exceeding those corresponding to their radiative cooling time. The hydrodynamic instability of the flow ejection causes precession, the formation of a conical helical flow structure with an increasing pitch. The reaction of the flows curves the disk and the helix axes. The spectra of compact fragments in the high-velocity bipolar outflow have lowfrequency cutoffs determined by reabsorption and absorption in the thermal plasma of the screen. The cutoff frequencies in the spectra increase as the center is approached and pass into the millimeter wavelength range. The screen thickness reaches 0.05 pc; the electron density is 104–105 cm−3. The magnetic fields of the bipolar outflow fragments are 50 mG ≤ B ≤ 500 mG at the nozzle exit and B ≈ 200 μG in the remote part at ρ ≥ 0.25 mas. The rotation measure toward the core center is RM ≈ 104 rad m−2. The sign of the rotation measure in the remote part of the bipolar outflow determined by the helical shape is reversed. The longitudinal magnetic field of the screen toward the central part of the core is BII ≈ 10 μG and falls at the edges of the active region to BII ≈ 2 μG.