Oral Presentation

Interplay among Black Holes, Galaxies, and AGN Jets

Author(s): Masanori Nakamura et al.

Presenter: Masanori Nakamura (ASIAA)

M87, one of the most studied active radio galaxies, has been spatially resolved from ten to tens of millions of Schwarzshild radii; it gives a unique opportunity for understanding an AGN jet from birth to termination. In this talk, several fundamental properties in AGN jets are extensively discussed based on multi-frequency observations and magnetohydrodynamic (MHD) jet theories toward M87. One of our remarkable findings in M87 is the "jet break", a structural change from parabolic to conical geometry, which coincides to a transition between increasing and decreasing observed proper motions. The jet break occurs at around the sphere of the gravitational influence (SGI) of the supermassive black hole (SMBH) with six billion solar masses, indicating the jet is under a certain control (confined) by the stratified ISM, radiatively inefficient accretion flows, and then becomes ballistic in the cooling core region of the host elliptical galaxy. The jet break in M87 is also accompanied by the narrowly focused, bright VHE gamma-ray flaring site, HST-1, where recurrent superluminal knot ejections take place simultaneously. The MHD bulk acceleration presumably takes place in M87 up to the SGI. Thus, we suggest that M87 is the best example to understand how an AGN jet behaves under the interplay with the SMBH growth and the early-type galaxy evolution.