The Bright Supernova 1996cr in the Circinus Galaxy Imaged with VLBI: Shell Structure with Complex Evolution

Abstract

We present broadband radio flux-density measurements supernova (SN) 1996cr, made with MeerKAT, ATCA and ALMA, and images made from very long baseline interferometry (VLBI) observations with the Australian Long Baseline Array. The spectral energy distribution of SN 1996cr in 2020, at age, $t\sim$8700 d, is a power-law, with flux density, $S\propto {\nu }^{-0.588\pm 0.011}$ between 1 and 34 GHz, but may steepen at $>35$ GHz. The spectrum has flattened since $t=5370$ d (2010). Also since $t=5370$ d, the flux density has declined rapidly, with $S_{9\mathrm{GHz}}\propto t^{-2.9}$. The VLBI image at $t=8859$ d shows an approximately circular structure, with a central minimum reminiscent of an optically-thin spherical shell of emission. For a distance of 3.7 Mpc, the average outer radius of the radio emission at $t=8859$ d was $(5.1\pm 0.3)\times 10^{17}$ cm, and SN 1996cr has been expanding with a velocity of $4650\pm 1060$ km s${}^{-1}$ between $t=4307$ and 8859 d. It must have undergone considerable deceleration before $t=4307$ d. Deviations from a circular shell structure in the image suggest a range of velocities up to $\sim$7000 km s${}^{-1}$, and hint at the presence of a ring- or equatorial-belt-like structure rather than a complete spherical shell.

arXiv comment10 Pages, 5 figures; Accepted for publication in MNRAS; this version (3) differs from version 2 by further minor revision

References in corpus (32)

• CASA, the Common Astronomy Software Applications for Radio Astronomy
• Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars
• High Density Circumstellar Interaction in the Luminous Type IIn SN 2010jl: The first 1100 days
• Metamorphosis of SN 2014C: Delayed Interaction Between a Hydrogen Poor Core-collapse Supernova and a Nearby Circumstellar Shell
• The 1.28 GHz MeerKAT Galactic Center Mosaic
• Thermal and non-thermal emission from circumstellar interaction
• What are Published X-ray lightcurves telling us about Young Supernova Expansion?
• On the Origin of Strong Magnetic Fields in Young Supernova Remnants
• Supernova 1987A: a Template to Link Supernovae to their Remnants
• The Radio Luminosity-Risetime Function of Core-Collapse Supernovae
• Supernova 1996cr: SN 1987A's Wild Cousin?
• SN 1993J VLBI (III): The Evolution of the Radio Shell
• A Chandra Study of the Circinus Galaxy Point-Source Population
• 3D MHD modeling of the expanding remnant of SN 1987A. Role of magnetic field and non-thermal radio emission
• SN 1993J VLBI (IV): A Geometric Determination of the Distance to M81 with the Expanding Shock Front Method
• Bursting SN 1996cr's Bubble: Hydrodynamic and X-ray Modeling of its Circumstellar Medium
• On the accuracy of the ALMA flux calibration in the time domain and across spectral windows
• X-ray imaging of the Seyfert 2 galaxy Circinus with Chandra
• SN 1986J VLBI: II. The Evolution of the Shell and the Central Source
• Absolute Calibration of the Radio Astronomy Flux Density Scale at 22 to 43 GHz Using Planck
• Multi-dimensional simulations of the expanding supernova remnant of SN 1987A
• A systematic reclassification of type IIn supernovae
• 21 new long-term variables in the GX 339-4 field: two years of MeerKAT monitoring
• SN 2014C: VLBI Images of a Supernova Interacting with a Circumstellar Shell
• SN 1986J VLBI. IV. The Nature of the Central Component
• The Exceptional X-ray Evolution of SN1996cr in High Resolution
• Performing a stellar autopsy using the radio-bright remnant of SN 1996cr
• SN 2014C: VLBI image shows a shell structure and decelerated expansion
• Ionization-Gasdynamic Simulations of Wind-Blown Nebulae around Massive Stars
• Spectral state transitions in Circinus ULX5
• Ultra Luminous X-ray sources - new distance indicators?
• Modeling SN 1996cr's X-ray lines at high-resolution: Sleuthing the ejecta/CSM geometry