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Astron. Astrophys. 326, 501-504

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Gas kinematics of the z = 3.8 radiogalaxy 4C 41.17

G. Adam1, B. Rocca-Volmerange2,3, S. Gérard2, P. Ferruit1, and R. Bacon1

1C.R.A.L., Observatoire de Lyon, F-69561 St-Genis-Laval Cedex, France
2Institut d'Astrophysique de Paris, CNRS, 98bis Bd Arago F-75014 Paris, France
3Université Paris XI, I.A.S., Bat 121, F-91405 Orsay Campus, France

Received 11 July 1996 / Accepted 18 February 1997


This paper presents the LyFORMULA 1215 Å image, the velocity and velocity dispersion maps of the radiogalaxy 4C 41.17 (z = 3.8), obtained with the integral field spectrograph TIGER at CFHT. In a relatively short exposure time (1.86 h), the LyFORMULA image reveals a bended elongated component surrounding a narrow bright peak and a West fainter component distributed along the radio axis. Roughly perpendicular to that main axis, a South-East to North-West faint extension to the central region is visible. A high density of smaller ionised clouds shows up in the vicinity of the radiogalaxy. The radial velocity and the velocity dispersion are mapped with a 0.61'' spatial sampling. Radial velocities, from 0 to 700 km s-1, are essentially negative relative to the narrow peak, while velocity dispersions vary from 800 km s-1 in the inner part up to 2000 km s-1 at possible bow shock locations as well as in the South extension. Such data are essential to disentangle the various components of these distant sources. The kinematics, roughly similar to that of nearby galaxies, is interpreted by luminous clouds and a dusty disk structure. Measured negative velocities could be used as expansion rate constraints for hydrodynamics models of the radio jet propagation. They may also be due to an overestimate of the systemic velocity, in the hypothesis of a collapsing bright knot at the central bright peak. Information on star formation triggering along the radiojet will be derived from deeper observations.

Key words: galaxies: evolution; intergalactic medium; kinematics and dynamics; jets

*Based on observations collected at Canada-France-Hawaii Telescope, which is operated by CNRS of France, NRC of Canada, and the University of Hawaii.

Send offprint requests to: G. Adam, ga@obs.univ-lyon1.fr

© European Southern Observatory (ESO) 1997

Online publication: September 18, 1997
Last change: October 15, 1997