Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz

Abstract

Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) which are mostly selected from the observing list of RadioAstron AGN monitoring campaigns. The observations were carried out at 4.8 GHz in two sessions of 8-12 February 2014 and 7-9 March respectively. We report the data reduction and the first results of observations. The results show that the majority of the blazars exhibit IDV in 99.9% confidence level, some of them show quite strong IDV. We find the strong IDV of blazar 1357 + 769 for the first time. The IDV at centimeter-wavelength is believed to be predominately caused by the scintillation of blazar emission through the local interstellar medium in a few hundreds parsecs away from Sun. No significant correlation between the IDV strength and either redshift or Galactic latitude is found in our sample. The IDV timescale along with source structure and brightness temperature analysis will be presented in a forthcoming paper.

12 pages, 4 figures and 3 tables, pulished in Universe 2021, 7(1), 15

References in corpus (13)

• CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources
• Relativistic Beaming and the Intrinsic Properties of Extragalactic Radio Jets
• The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey II: The First Four Epochs
• F-GAMMA: Variability Doppler factors of blazars from multiwavelength monitoring
• A Large Sample of BL Lacs from SDSS and FIRST
• Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure
• Angular Broadening of Intraday Variable AGN. II. Interstellar and Intergalactic Scattering
• The IDV source J1128+5925, a new candidate for annual modulation?
• Brightness temperature constraints from interferometric visibilities
• Intra-day variability observations of S5 0716+714 over 4.5 years at 4.8 GHz
• Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. III. Blazar S5 0716+71 at microarcsecond resolution
• Spica and the annual cycle of PKS B1322-110 scintillations
• Intra-day variability observations and the VLBI structure analysis of quasar S4 0917+624