2008/10/28 by Ian Heywood, Katherine M. Blundell, H.-R. Klöckner +3 · 10 citations
Engineering · Physics and Astronomy · #Amplitude #Astronomy #Astrophysics #Azimuth #Brightness #Gamma-ray bursts and supernovae #Interferometry #Optics #Physics #Spacecraft and Cryogenic Technologies #Supernova #Very-long-baseline interferometry #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.14102.x
published in Monthly Notices of the Royal Astronomical Society 392(2), 855-867 (Oxford University Press) · 14 pages, 10 figures, 2 tables, accepted for publication in MNRAS
arxiv created 2008/10/28 · openalex publication_date 2008/12/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present simulated images of Supernova 1993J at 8.4 GHz using Very Long Baseline Interferometry (VLBI) techniques. A spherically symmetric source model is convolved with realistic uv-plane distributions, together with standard imaging procedures, to assess the extent of instrumental effects on the recovered brightness distribution. In order to facilitate direct comparisons between the simulations and published VLBI images of SN 1993J, the observed uv-coverage is determined from actual VLBI observations made in the years following its discovery. The underlying source model only exhibits radial variation in its density profile, with no azimuthal dependence and, even though this model is morphologically simple, the simulated VLBI observations qualitatively reproduce many of the azimuthal features of the reported VLBI observations, such as appearance and evolution of complex azimuthal structure and apparent rotation of the shell. We demonstrate that such features are inexorably coupled to the uv-plane sampling. The brightness contrast between the peaks and the surrounding shell material are not as prominent in the simulations (which of course assume no antenna- or baseline-based amplitude or phase errors, meaning no self-calibration procedures will have incorporated any such features in models). It is conclusive that incomplete uv-plane sampling has a drastic effect on the final images for observations of this nature. Difference imaging reveals residual emission up to the 8σ level. Extreme care should be taken when using interferometric observations to directly infer the structure of objects such as supernovae.