Intra-day variability observations of S5 0716+714 over 4.5 years at 4.8 GHz

Abstract

We aim to search for evidence of annual modulation in the time scales of the BL Lac object S5 0716+714. The intra-day variability (IDV) observations were carried out monthly from 2005 to 2009, with the Urumqi 25m radio telescope at 4.8 GHz. The source has shown prominent IDV as well as long-term flux variations. The IDV time scale does show evidence in favor of an annual modulation, suggesting that the IDV of 0716+714 is dominated by interstellar scintillation. The source underwent a strong outburst phase between mid-2008 and mid-2009; a second intense flare was observed in late 2009, but no correlation between the total flux density and the IDV time scale is found, implying that the flaring state of the source does not have serious implications for the general characteristics of its intra-day variability. However, we find that the inner-jet position angle is changing throughout the years, which could result in an annual modulation noise in the anisotropic ISS model fit. There is also an indication that the lowest IDV amplitudes (rms flux density) correspond to the slowest time scales of IDV, which would be consistent with an ISS origin of the IDV of 0716+714.

6 pages, 7 figures, accepted for publication in A&A; corrected typos in Table 2

References in corpus (9)

• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. V. Multi-epoch VLBA Images
• The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey II: The First Four Epochs
• A Sino-German lambda6 cm polarization survey of the Galactic plane I. Survey strategy and results for the first survey region
• Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71, III. Rapid and correlated flux density variability from radio to sub-mm bands
• Radio variability properties for radio sources
• Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure
• The Origin of Radio Scintillation In the Local Interstellar Medium
• The IDV source J1128+5925, a new candidate for annual modulation?
• Emergence and disappearance of micro-arcsecond structure in the scintillating quasar J1819+3845

Cited by in corpus (4)

• Multi-wavelength Intra-day Variability and Quasi-periodic Oscillation in Blazars
• Interferometric Monitoring of Gamma-ray Bright AGNs: S5 0716+714
• Intra-day variability observations and the VLBI structure analysis of quasar S4 0917+624
• 4.8 GHz Intra-Day Variability of FSRQ 0507+179