Interstellar Scintillation of an Extreme Scintillator: PKS B1144-379
arXiv:2009.00812 · doi:10.1093/mnras/staa2642
Abstract
The University of Tasmania Ceduna radio telescope has been used to investigate rapid variability in the radio flux density of the BL Lac object PKS B1144-379 at 6.7 GHz. High-cadence monitoring of this extreme scintillator was carried out over a period of approximately nine years, between 2003 and 2011. We have used structure functions created from the intensity time series to determine the characteristic timescale of the variability. The characteristic timescale is consistently observed to increase during certain periods of each year, demonstrating the annual cycle expected for scintillation through an interstellar scattering screen. The best-fitting annual cycle model for each year suggests that the scintillation pattern has an anisotropic structure and that the upper limit of its scattering screen is at a distance of ~0.84 kpc. Higher anisotropy in some of the annual cycle fits suggests that changes in the intrinsic source structure might be influencing the variability timescale. We found a prominent annual cycle is only present in the variability timescale for certain years where other evidence suggests that the core is compact. From our measurements, we calculated that the core angular size varied between 5.65-15.90 as (0.05-0.13 pc). The core component was found to be at its most compact during two flares in the total flux density, which were observed in 2005 and 2008. We conclude that the long-term variability in the radio flux density of PKS B1144-379 is due to intrinsic changes in the source and that these affect our ability to measure an annual cycle in its variability time scale.
arXiv comment24 pages, 22 figures
References in corpus (39)
- Blazars in the Fermi Era: The OVRO 40-m Telescope Monitoring Program
- Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
- MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. V. Multi-epoch VLBA Images
- The discovery of a microarcsecond quasar: J1819+3845
- PKS 0405--385: the smallest radio quasar?
- Rapid Variability and Annual Cycles in the Characteristic Time-scale of the Scintillating Source PKS 1257-326
- The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey II: The First Four Epochs
- Interstellar scintillation as the origin of rapid radio variability in the quasar J1819+3845
- TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry I. First-Epoch 8.4 GHz Images
- Anomalous Radio-Wave Scattering from Interstellar Plasma Structures
- Interstellar Scintillation of the Polarized Flux Density in Quasar, PKS 0405-385
- Annual modulation in the scattering of J1819+3845: peculiar plasma velocity and anisotropy
- Pulsar scintillations from corrugated reconnection sheets in the ISM
- Annual modulation in IDV of quasar 0917+624 due to Interstellar Scintillation
- The ATCA Intraday Variability Survey of Extragalactic Radio Sources
- Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure
- The first estimate of radio jet proper motion at z>5
- Intra-Day Variability and the Interstellar Medium Towards 0917+624
- Folded Fields as the Source of Extreme Radio-Wave Scattering in the Galactic Center
- Interstellar Scintillation Observations of 146 Extragalactic Radio Sources
- The IDV source J1128+5925, a new candidate for annual modulation?
- Extreme radio-wave scattering associated with hot stars
- Emergence and disappearance of micro-arcsecond structure in the scintillating quasar J1819+3845
- Intra-day variability observations of S5 0716+714 over 4.5 years at 4.8 GHz
- Microarcsecond Radio Imaging using Earth Orbit Synthesis
- Annual Modulation in the Variability Properties of the IDV-Source 0917+624 ?
- A seasonal cycle and an abrupt change in the variability characteristics of the intraday variable source S4 0954+65
- Extremely Anisotropic Scintillations
- Radio and optical intra-day variability observations of five blazars
- Detection of Six Rapidly Scintillating AGNs and the Diminished Variability of J1819+3845
- A Compact Extreme Scattering Event Cloud Towards AO 0235+164
- Two-year monitoring of intra-day variability of quasar 1156+295 at 4.8 GHz
- The effects of frequency-dependent quasar variability on the celestial reference frame
- Spica and the annual cycle of PKS B1322-110 scintillations
- Annual Cycles in the Interstellar Scintillation Timescales of PKS B1519-273 and PKS B1622-253
- Very Long Baseline Array observations of the Intraday Variable source J1128+592
- Rapid variability of BL Lac 0925+504: interstellar scintillation induced?
- J1128+592: a highly variable IDV source
- BL LAC PKSB1144-379 an extreme scintillator