SN 1986J VLBI. III. The Central Component Becomes Dominant

Abstract

We present a new 5-GHz global-VLBI image of supernova 1986J, observed in 2014 at $t=31.6$ yr after the explosion, and compare it to previous images to show the evolution of the supernova. Our new image has a dynamic range of ~100 and a background rms noise level of 5.9 $\mu$Jy beam${}^{-1}$. There is no significant linear polarization, with the image peak being $<$3% polarized. The latest image is dominated by the compact central component, whose flux density is now comparable to that of the extended supernova shell. This central component is marginally resolved with a FWHM width of $900_{-500}^{+100}\mu$as, corresponding to a radius of $r_{\mathrm{comp}}=6.7_{-3.7}^{+0.7}\times 10^{16}$ cm for a distance of 10 Mpc. Using VLBI observations between 2002 and 2014, we measured the proper motions of both the central component and a hot-spot to the NE in the shell relative to the quasar 3C66A. The central component is stationary to within the uncertainty of 12 $\mu$as yr${}^{-1}$, corresponding to 570 km s${}^{-1}$. Our observations argue in favor of the central component being located near the physical center of SN 1986J. The shell hot-spot had a mean velocity of 2810+-750 km s${}^{-1}$ to the NE, which is consistent with it taking part in the homologous expansion of the shell seen earlier. The shell emission is evolving in a non-selfsimilar fashion, with the brightest emission shifting inwards within the structure, and with only relatively faint emission being seen near the outer edge and presumed forward shock. An animation is available.

Accepted to for publication in the Astrophysical Journal (revised according to referee's suggestions) 9 pages, 4 figures. Animation available in source package

References in corpus (9)

• Multi-Scale CLEAN deconvolution of radio synthesis images
• Astrometric accuracy of phase-referenced observations with the VLBA and EVN
• Explaining the most energetic supernovae with an inefficient jet-feedback mechanism
• Multi-Scale CLEAN: A comparison of its performance against classical CLEAN in galaxies using THINGS
• Spectral and morphological analysis of the remnant of Supernova 1987A with ALMA & ATCA
• High-resolution radio observations of SNR 1987A at high frequencies
• Aperture Synthesis Observations of the Nearby Spiral NGC 6503: Modeling the Thin and Thick HI Disks
• The Evolution of Late-time Optical Emission from SN 1986J
• Shell revealed in SN 1979C

Cited by in corpus (8)

• The Radio Luminosity-Risetime Function of Core-Collapse Supernovae
• A Search for Late-Time Radio Emission and Fast Radio Bursts from Superluminous Supernovae
• The Re-Acceleration of the Shock Wave in the Radio Remnant of SN 1987A
• The double-peaked radio light curve of PTF11qcj
• SN 2014C: VLBI Images of a Supernova Interacting with a Circumstellar Shell
• SN 1986J VLBI. IV. The Nature of the Central Component
• Late-Time Evolution and Modeling of the Off-Axis Gamma-ray Burst Candidate FIRST J141918.9+394036
• On the Possibility of Fast Radio Bursts from Inside Supernovae: The Case of SN 1986J