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Title: DISCOVERY OF SUB- TO SUPERLUMINAL MOTIONS IN THE M87 JET: AN IMPLICATION OF ACCELERATION FROM SUB-RELATIVISTIC TO RELATIVISTIC SPEEDS

The velocity field of the M87 jet from milli-arcsecond (mas) to arcsecond scales is extensively investigated together with new radio images taken from European VLBI Network (EVN) observations. We detected proper motions of components located at between 160┬ámas from the core and the HST-1 complex for the first time. Newly derived velocity fields exhibit a systematic increase from sub- to superluminal speeds in the upstream of HST-1. If we assume that the observed velocities reflect the bulk flow, here we suggest that the M87 jet may be gradually accelerated through a distance of 10{sup 6} times the Schwarzschild radius of the supermassive black hole. The acceleration zone is co-spatial with the jet parabolic region, which is interpreted as the collimation zone of the jet. The acceleration and collimation take place simultaneously, which we suggest is characteristic of magnetohydrodynamic flows. The distribution of the velocity field has a peak at HST-1, which is considered as the site of over-collimation, and shows a deceleration downstream of HST-1 where the jet is conical. Our interpretation of the velocity map in the M87 jet provides a hypothesis for active galactic nuclei which suggests that the acceleration and collimation zone of relativistic jets extends overmore » the whole scale within the sphere of influence of the supermassive black hole.« less
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)
  2. Institute of Space and Astronautial Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuou-ku, Sagamihara, Kanagawa 229-8510 (Japan)
  3. National Astronomical Observatory of Japan, 2-21-1, Osawa, Tokyo 81-8588 (Japan)
Publication Date:
OSTI Identifier:
22364035
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 781; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; BLACK HOLES; GALAXIES; GALAXY NUCLEI; IMAGES; JETS; PROPER MOTION; RELATIVISTIC RANGE; SCHWARZSCHILD RADIUS; VELOCITY