Features of Structure and Absorption in the Jet-Launching Region of M87

Abstract

M87 is one of the best available source for studying the AGN jet-launching region. To enrich our knowledge of this region, with quasi-simultaneous observations using VLBA at 22, 43 and 86 GHz, we capture the images of the radio jet in M87 on a scale within several thousand R s . Based on the images, we analyze the transverse jet structure and obtain the most accurate spectral-index maps of the jet in M87 so far, then for the first time, we compare the results of the two analyses and find a spatial association between the jet collimations and the local enhancement of the density of external medium in the jet-launching region. We also find the external medium is not uniform, and greatly contributes to the free-free absorption in this region. In addition, we find for the jet in M87, its temporal morphology in the launching region may be largely affected by the local, short-lived kink instability growing in itself.

Accepted by Galaxies

References in corpus (7)

• A Global 86GHz VLBI Survey of Compact Radio Sources
• Faraday rotation in the jet of M87 inside the Bondi radius: indication of winds from hot accretion flows confining the relativistic jet
• Aligning VLBI Images of Active Galactic Nuclei at Different Frequencies
• The internal structure of overpressured, magnetized, relativistic jets
• The first estimate of radio jet proper motion at z>5
• MHD simulations of three-dimensional Resistive Reconnection in a cylindrical plasma column
• VIMAP: an Interactive Program Providing Radio Spectral Index Maps of Active Galactic Nuclei