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Titolo:
THE RADIO JET OF QUASAR 0153+744
Autore:
HUMMEL CA; KRICHBAUM TP; WITZEL A; WULLNER KH; STEFFEN W; ALEF W; FEY A;
Indirizzi:
UNIV SPACE RES ASSOC,300 D ST SW,SUITE 801 WASHINGTON DC 20024 USN OBSERV WASHINGTON DC 20392 MAX PLANCK INST RADIOASTRON D-53121 BONN GERMANY UNIV MANCHESTER,DEPT PHYS & ASTRON MANCHESTER M13 9PL LANCS ENGLAND
Titolo Testata:
Astronomy and astrophysics
fascicolo: 3, volume: 324, anno: 1997,
pagine: 857 - 869
SICI:
0004-6361(1997)324:3<857:TRJOQ0>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
MILLIARCSECOND POLARIZATION STRUCTURE; COMPACT SYMMETRICAL OBJECTS; PEARSON-READHEAD SAMPLE; BANK VLBI SURVEY; RELATIVISTIC JETS; 24 OBJECTS; EVOLUTION; 3C-345; VARIABILITY; NUCLEI;
Keywords:
GALAXIES, JETS; QUASARS, GENERAL; QUASARS, INDIVIDUAL, 0153+744;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
47
Recensione:
Indirizzi per estratti:
Citazione:
C.A. Hummel et al., "THE RADIO JET OF QUASAR 0153+744", Astronomy and astrophysics, 324(3), 1997, pp. 857-869

Abstract

We present new high resolution VLBI images of the radio structure of quasar O153+744 (z = 2.338) at lambda lambda 13 cm, 6 cm, 3.6 cm, and 1.3 cm, and show that its jet as projected on the sky changes direction by a full 180 degrees between the core-jet component (A) and the bright secondary component (B) located only 10 milliarcseconds away from the core. Using images published for earlier epochs, we conclude that component B is stationary with respect to A and place an upper limit of 0.7 c (H-0 = 100 km s(-1) Mpc(-1), q(0) = 0.5) on any apparent motion. No component motions are found in the jet either, albeit with a less stringent upper limit. This is in contrast to the superluminal motion typically found in flat-spectrum radio sources, of which class O153+744 is a member. Component A is resolved at a wavelength of 1.3 cm into a core-jet structure with four distinct components, whereas B shows complex structure consisting of resolved steep-spectrum emission. At lower resolution, the structure of B is very similar at 1.3 cm and at 6cm. Using B as a reference position, we measure a dependence of the core peak brightness position on the observing frequency in accordance with models for inhomogeneous synchrotron components. We find the spectral index of the optically thin emission of B to be close to the one of the steep-spectrum jet components between 6 cm and 3.6 cm. No extended emission is found on scales larger than about 1 arcsecond in new VLA images made at 20 cm in A and C configuration. We discuss a model of a precessing mildly relativistic jet for O153+744, and show that a reasonable fit to the observed properties of the radio structure is achieved. In this model, component B is the result of jet components superposed along the line-of-sight (LOS) and enhanced Doppler boosting dueto their moving close to the LOS. The new components found close to the core with VLBI at lambda = 1.3 cm are sufficiently well-defined so that they may be studied in future VLBI experiments to detect motion, if any, which would further constrain, or perhaps falsify, the precessing beam model.

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Documento generato il 23/11/20 alle ore 21:32:14