2009/09/21 by T. M. Potter, L. Staveley-Smith, C.-Y. Ng +7 · 1 citation
Physics and Astronomy · #Angular resolution (graph drawing) #Astrophysics and Cosmic Phenomena #Cassiopeia A #Flux (metallurgy) #Gamma-ray bursts and supernovae #RADIUS #Radio spectrum #Solar and Space Plasma Dynamics #Spectral index #Supernova remnant #Telescope #Torus #Very-long-baseline interferometry #astro-ph.CO #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/705/1/261
published as Astrophys.J.705:261-271,2009 · 34 pages, 9 figures in single column manuscript form
arxiv created 2009/09/21 · openalex publication_date 2009/10/09 · arxiv updated 2014/11/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
The aftermath of supernova (SN) 1987A continues to provide spectacular insights into the interaction between an SN blastwave and its circumstellar environment. We here present 36 GHz observations from the Australia Telescope Compact Array of the radio remnant of SN 1987A. These new images, taken in 2008 April and 2008 October, substantially extend the frequency range of an ongoing monitoring and imaging program conducted between 1.4 and 20 GHz. Our 36.2 GHz images have a diffraction-limited angular resolution of 0 3–0 4, which covers the gap between high resolution, low dynamic range VLBI images of the remnant and low resolution, high dynamic range images at frequencies between 1 and 20 GHz. The radio morphology of the remnant at 36 GHz is an elliptical ring with enhanced emission on the eastern and western sides, similar to that seen previously at lower frequencies. Model fits to the data in the Fourier domain show that the emitting region is consistent with a thick inclined torus of mean radius 0 85, and a 2008 October flux density of 27 ± 6 mJy at 36.2 GHz. The spectral index for the remnant at this epoch, determined between 1.4 GHz and 36.2 GHz, is α = −0.83. There is tentative evidence for an unresolved central source with flatter spectral index.