High frequency VLA observations of low-redshift quasars: Core structure, variability, and orientation

Abstract

view Abstract Citations (19) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High Frequency VLA Observations of Low-Redshift Quasars: Core Structure, Variability, and Orientation Lister, Matthew L. ; Gower, Ann C. ; Hutchings, J. B. Abstract We discuss high-frequency radio maps of 33 low-redshift quasars, taken with the VLA (Very Large Array) in the A-configuration, at 1.3,2, and 6 cm. In six sources we report the detection of new detailed structure. The 6 cm data are second-epoch observations and are used in discussion of core variability. Core variability is found to be present in both lobe- and core-dominated sources, with 12 quasars displaying significant flux changes over the two epochs. The majority of variable sources have flat or positive spectral indices, in agreement with other recent variability studies. We also consider the core fraction distribution of our sample of 114 quasars to redshift 2. This quantity does not correlate with source bend-angle or lobe length ratio as might be expected if the core flux is enhanced due to beaming when the source is aligned close to the line of sight. We confirm the correlation with apparent size, with a few exceptions, and show that these results are consistent with a source evolution scenario discussed in earlier papers. Publication: The Astronomical Journal Pub Date: September 1994 DOI: 10.1086/117113 Bibcode: 1994AJ....108..821L Keywords: Astronomical Maps; Cores; Extraterrestrial Radio Waves; Quasars; Radio Astronomy; Radio Spectra; Red Shift; Very Large Array (Vla); Antenna Arrays; Correlation; Graphs (Charts); Radio Jets (Astronomy); Sampling; Tables (Data); Variations; Astronomy; QUASARS: EMISSION LINES; RADIO CONTINUUM: GALAXIES; GALAXIES: IMAGING full text sources ADS | data products NED (33) SIMBAD (32)