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Subluminal motion and limb brightening in the nuclear jet of M87

1989; IOP Publishing; Volume: 336; Linguagem: Inglês

10.1086/166998

1538-4357

M. J. Reid, J. A. Biretta, W. Junor, T. W. B. Muxlow, R. E. Spencer,

Radio Astronomy Observations and Technology

view Abstract Citations (141) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Subluminal Motion and Limb Brightening in the Nuclear Jet of M87 Reid, M. J. ; Biretta, J. A. ; Junor, W. ; Muxlow, T. W. B. ; Spencer, R. E. Abstract We conducted an 18 station VLBI observation to map the nucleus of M87 at 18 cm wavelength. The resulting image has a dynamic range greater than 2000 to 1 and resolves the continuous, well-collimated, nuclear jet both along and perpendicular to the jet axis. The nuclear jet displays complicated structures including limb brightening, side-to-side oscillations, and transverse expansion. These phenomena are suggestive of hydrodynamic processes. The parsec-scale jet appears morphologically similar to the kiloparsec-scale jet in M87 and in other sources. Comparison of this map with previous VLBI maps gives strong evidence for subluminal motion of knots in the nuclear jet. We argue that simple versions of the standard beaming model cannot explain the observations. Constraints on the jet flow speed and its orientation to the line of sight by the absence of a detectable counterjet (Doppler boosting), by the subluminal motion of parsec-scale knots, and by the "edge-on" appearance of knot A in the kiloparsec-scale jet are mutually exclusive in the context of simple beaming models. This suggests that motions of knots at the parsec-scale are slower than the flow of material in the jet, or that the jet is intrinsically one-sided and has only a mildly relativistic (β ~ 0.3) flow speed. Publication: The Astrophysical Journal Pub Date: January 1989 DOI: 10.1086/166998 Bibcode: 1989ApJ...336..112R Keywords: Active Galactic Nuclei; Extragalactic Radio Sources; Limb Brightening; Radio Jets (Astronomy); Very Long Base Interferometry; Elliptical Galaxies; Flow Velocity; Northern Hemisphere; Virgo Galactic Cluster; Astrophysics; GALAXIES: INDIVIDUAL MESSIER NUMBER: M87; GALAXIES: JETS; GALAXIES: NUCLEI; INTERFEROMETRY; RADIO SOURCES: GALAXIES full text sources ADS | data products SIMBAD (5) NED (4)