Volume 489, Number 2, October II 2008
|Page(s)||517 - 524|
|Published online||23 July 2008|
Multi-frequency investigation of the parsec- and kilo-parsec-scale radio structures in high-redshift quasar PKS 1402+044
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, 200030 Shanghai, PR China e-mail: firstname.lastname@example.org
2 Graduate University of the Chinese Academy of Sciences, Beijing, PR China
3 Joint Institute for VLBI in Europe, PO Box 2, 7990 AA Dwingeloo, The Netherlands e-mail: email@example.com
4 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: firstname.lastname@example.org
5 FÖMI Satellite Geodetic Observatory, PO Box 585, 1592 Budapest, Hungary e-mail: email@example.com
6 MTA Research Group for Physical Geodesy and Geodynamics, PO Box 91, 1521 Budapest, Hungary
Accepted: 16 June 2008
Aims. We investigate the frequency-dependent radio properties of the jet of the luminous high-redshift () radio quasar PKS 1402+044 (J1405+0415) by means of radio interferometric observations.
Methods. The observational data were obtained with the VLBI Space Observatory Programme (VSOP) at 1.6 and 5 GHz, supplemented by other multi-frequency observations with the Very Long Baseline Array (VLBA; 2.3, 8.4, and 15 GHz) and the Very Large Array (VLA; 1.4, 5, 15, and 43 GHz). The observations span a period of 7 years.
Results. We find that the luminous high-redshift quasar PKS 1402+044 has a pronounced “core-jet” morphology from the parsec to the kilo-parsec scales. The jet shows a steeper spectral index and lower brightness temperature with increasing distance from the jet core. The variation of brightness temperature agrees well with the shock-in-jet model. Assuming that the jet is collimated by the ambient magnetic field, we estimate the mass of the central object as ~. The upper limit of the jet proper motion of PKS 1402+044 is 0.03 mas yr-1 (~) in the east-west direction.
Key words: galaxies: individual: PKS 1402+044 / galaxies: active / galaxies: quasars: general / galaxies: jets / radio continuum: galaxies
© ESO, 2008
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