Fifteen Years of High-Resolution Radio Imaging of Supernova 1987A

Gaensler, B. M.; Manchester, R. N.; Kesteven, M. J.; Ball, Lewis; Tzioumis, A. K.

doi:10.1063/1.2803627

Cited by 10 publications

(11 citation statements)

References 23 publications

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“…On the other hand, we note that a similar plot with azimuthally averaged u-v data (Fig. 6 in Gaensler et al 2007) masks the discrepancy between the data and a simple shell model. To provide a quantitative comparison between different models, we have reproduced the fits with a thin-shell model and a thin spherical shell plus two points model, as in Manchester et al (2002).…”

Section: Ghz Observationsmentioning

confidence: 88%

“…Each was taken 1 day before or after a 9 GHz observation, thus allowing a direct comparison between the two frequency bands. Except for the last epoch, a preliminary analysis of all 9 and 18 GHz data has been presented in Gaensler et al (2007).…”

Section: Observationsmentioning

confidence: 99%

“…However, Gaensler et al (2007) analyzed the Chandra for the diffraction-limited data and model images, and from 0 to 10 mJy beam À1 for the super-resolved images. As in Fig.…”

Section: Remnant Sizementioning

confidence: 99%

“…Also, due to the finite speed of light, expansion of the remnant distorts the torus and shifts its center to the north. To derive corrections for both effects, we employed linear approximations to the expansion and light curve locally at each epoch, with the rate of change determined from the results of Gaensler et al (2007) and Staveley-Smith et al (2007). We found that the northern rim is at most 20% brighter than the southern rim as a result of lighttravel effects.…”

Section: Equatorial Belt Torus Modelmentioning

confidence: 99%

“…Recently, Gaensler et al (2007) applied the thin-shell model to fit all 9 GHz observations from 1992 to 2006 and suggested a gradual acceleration in the expansion followed by a recent deceleration.…”

mentioning

confidence: 99%

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Fourier Modeling of the Radio Torus Surrounding SN 1987A

Gaensler

Staveley‐Smith

et al. 2008

Astrophysical Journal

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We present detailed Fourier modeling of the radio remnant of SN 1987A using high-resolution 9 and 18 GHz data taken with the Australia Telescope Compact Array over the period 1992-2008. We develop a parameterized threedimensional torus model for the expanding radio shell, in which the emission is confined to an inclined equatorial belt; our model also incorporates both a correction for light-travel time effects and an overall east-west gradient in the radio emissivity. By deriving an analytic expression for the two-dimensional Fourier transform of the projected threedimensional brightness distribution, we can fit our spatial model directly to the interferometric visibility data. This provides robust estimates of the radio morphology at each epoch. The best-fit results suggest a constant remnant expansion at 4000 AE 400 km s À1 over the 16 yr period covered by the observations. The model fits also indicate substantial midlatitude emission, extending to AE40 on either side of the equatorial plane. This likely corresponds to the extraplanar structure seen in H and Ly emission from the supernova reverse shock, and broadly supports hydrodynamic models in which the complex circumstellar environment was produced by a progression of interacting winds from the progenitor. Our model quantifies the clear asymmetry seen in the radio images: we find that the eastern half of the radio remnant is consistently $40% brighter than the western half at all epochs, which may result from an asymmetry in the ejecta distribution between these two hemispheres.

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Section: Ghz Observationsmentioning

confidence: 88%

Section: Observationsmentioning

confidence: 99%

“…However, Gaensler et al (2007) analyzed the Chandra for the diffraction-limited data and model images, and from 0 to 10 mJy beam À1 for the super-resolved images. As in Fig.…”

Section: Remnant Sizementioning

confidence: 99%

Section: Equatorial Belt Torus Modelmentioning

confidence: 99%

mentioning

confidence: 99%

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Fourier Modeling of the Radio Torus Surrounding SN 1987A

Gaensler

Staveley‐Smith

et al. 2008

Astrophysical Journal

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Time evolution of the line emission from the inner circumstellar ring of SN 1987A and its hot spots

Gröningsson

Fransson

Leibundgut

et al. 2008

A&A

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We present seven epochs between October 1999 and November 2007 of high resolution VLT/UVES echelle spectra of the ejecta-ring collision of SN 1987A. The fluxes of most of the narrow lines from the unshocked gas decreased by a factor of 2−3 during this period, consistent with the decay from the initial ionization by the shock break-out. However, [O III] in particular shows an increase up to day ∼6800. This agrees with radiative shock models where the pre-shocked gas is heated by the soft X-rays from the shock. The evolution of the [O III] line ratio shows a decreasing temperature of the unshocked ring gas, consistent with a transition from a hot, low density component which was heated by the initial flash ionization to the lower temperature in the pre-ionized gas ahead of the shocks. The line emission from the shocked gas increases rapidly as the shock sweeps up more gas. We find that the neutral and high ionization lines follow the evolution of the Balmer lines roughly, while the intermediate ionization lines evolve less rapidly. Up to day ∼6800, the optical light curves have a similar evolution to that of the soft X-rays. The break between day 6500 and day 7000 for [O III] and [Ne III] is likely due to recombination to lower ionization levels. Nevertheless, the evolution of the [Fe XIV] line, as well as the lines from the lowest ionization stages, continue to follow that of the soft X-rays, as expected. There is a clear difference in the line profiles between the low and intermediate ionization lines, and those from the coronal lines at the earlier epochs. This shows that these lines arise from regions with different physical conditions, with at least a fraction of the coronal lines coming from adiabatic shocks. At later epochs the line widths of the low ionization lines, however, increase and approach those of the high ionization lines of [Fe X−XIV]. The Hα line profile can be traced up to ∼500 km s −1 at the latest epoch. This is consistent with the cooling time of shocks propagating into a density of (1−4) × 10 4 cm −3 . This means that these shocks are among the highest velocity radiative shocks observed.

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HIGH RESOLUTION 36 GHz IMAGING OF THE SUPERNOVA REMNANT OF SN 1987A

Potter

Ball

et al. 2009

ApJ

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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.

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Fifteen Years of High-Resolution Radio Imaging of Supernova 1987A

Cited by 10 publications

References 23 publications

Fourier Modeling of the Radio Torus Surrounding SN 1987A

Fourier Modeling of the Radio Torus Surrounding SN 1987A

Time evolution of the line emission from the inner circumstellar ring of SN 1987A and its hot spots

HIGH RESOLUTION 36 GHz IMAGING OF THE SUPERNOVA REMNANT OF SN 1987A

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