THE INNERMOST COLLIMATION STRUCTURE OF THE M87 JET DOWN TO ∼10 SCHWARZSCHILD RADII
Open Access
- 5 September 2013
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 775 (1), 70
- https://doi.org/10.1088/0004-637x/775/1/70
Abstract
We investigated the detailed inner jet structure of M87 using Very Long Baseline Array data at 2, 5, 8.4, 15, 23.8, 43, and 86 GHz, especially focusing on the multi-frequency properties of the radio core at the jet base. First, we measured the size of the core region transverse to the jet axis, defined as W c, at each frequency ν, and found a relation between W c and ν: W c(ν)∝ν–0.71 ± 0.05. Then, by combining W c(ν) and the frequency dependence of the core position r c(ν), which was obtained in our previous study, we constructed a collimation profile of the innermost jet W c(r) down to ~10 Schwarzschild radii (R s) from the central black hole. We found that W c(r) smoothly connects with the width profile of the outer edge-brightened, parabolic jet and then follows a similar radial dependence down to several tens of R s. Closer to the black hole, the measured radial profile suggests a possible change in the jet collimation shape from the outer parabolic one, where the jet shape tends to become more radially oriented. This result could be related to a magnetic collimation process or/and interactions with surrounding materials at the jet base. The present results shed light on the importance of higher-sensitivity/resolution imaging studies of M87 at 86, 43, and 22 GHz; these studies should be examined more rigorously.Keywords
This publication has 48 references indexed in Scilit:
- THE 2010 VERY HIGH ENERGY γ-RAY FLARE AND 10 YEARS OF MULTI-WAVELENGTH OBSERVATIONS OF M 87The Astrophysical Journal, 2012
- THE STRUCTURE OF THE M87 JET: A TRANSITION FROM PARABOLIC TO CONICAL STREAMLINESThe Astrophysical Journal Letters, 2012
- FERMILARGE AREA TELESCOPE GAMMA-RAY DETECTION OF THE RADIO GALAXY M87The Astrophysical Journal, 2009
- Radio Imaging of the Very-High-Energy γ-Ray Emission Region in the Central Engine of a Radio GalaxyScience, 2009
- IMAGING THE BLACK HOLE SILHOUETTE OF M87: IMPLICATIONS FOR JET FORMATION AND BLACK HOLE SPINThe Astrophysical Journal, 2009
- Hydrodynamic Collimation of Relativistic Outflows: Semianalytic Solutions and Application to Gamma‐Ray BurstsThe Astrophysical Journal, 2007
- Superluminal Radio Features in the M87 Jet and the Site of Flaring TeV Gamma-Ray EmissionThe Astrophysical Journal, 2007
- Hubble Space TelescopeObservations of Superluminal Motion in the M87 JetThe Astrophysical Journal, 1999
- Hydromagnetic flows from accretion discs and the production of radio jetsMonthly Notices of the Royal Astronomical Society, 1982
- Relativistic jets as compact radio sourcesThe Astrophysical Journal, 1979