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Spectral and Morphological Analysis of the Remnant of Supernova 1987A with ALMA and ATCA

G. Zanardo ; L. Staveley-Smith ; R. Indebetouw ; R. A. Chevalier ; M. Matsuura ; B. M. Gaensler ; M. J. Barlow ; C. Fransson ; R. N. Manchester ; M. Baes ; J. R. Kamenetzky ; M. Lakicevic ; P. Lundqvist ; J. M. Marcaide ; Ivan Marti-Vidal (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; M. Meixner ; C. Y. Ng ; S. Park ; G. Sonneborn ; J. Spyromilio ; J. T. van Loon
Astrophysical Journal (0004-637X). Vol. 796 (2014), 2, p. Art. no. 82.
[Artikel, refereegranskad vetenskaplig]

We present a comprehensive spectral and morphological analysis of the remnant of supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal and thermal components of the radio emission are investigated in images from 94 to 672 GHz (lambda 3.2 mm to 450 mu m), with the assistance of a high-resolution 44 GHz synchrotron template from the ATCA, and a dust template from ALMA observations at 672 GHz. An analysis of the emission distribution over the equatorial ring in images from 44 to 345 GHz highlights a gradual decrease of the east-to-west asymmetry ratio with frequency. We attribute this to the shorter synchrotron lifetime at high frequencies. Across the transition from radio to far infrared, both the synchrotron/dust-subtracted images and the spectral energy distribution (SED) suggest additional emission beside the main synchrotron component (S-nu proportional to nu(-0.73)) and the thermal component originating from dust grains at T similar to 22 K. This excess could be due to free-free flux or emission from grains of colder dust. However, a second flat-spectrum synchrotron component appears to better fit the SED, implying that the emission could be attributed to a pulsar wind nebula (PWN). The residual emission is mainly localized west of the SN site, as the spectral analysis yields -0.4 less than or similar to alpha less than or similar to -0.1 across the western regions, with alpha similar to 0 around the central region. If there is a PWN in the remnant interior, these data suggest that the pulsar may be offset westward from the SN position.

Nyckelord: ISM: supernova remnants, radiation mechanisms: non-thermal, radiation mechanisms: thermal, radio continuum: general; stars: neutron; supernovae: individual (SN 1987A)

Denna post skapades 2014-12-22. Senast ändrad 2017-01-25.
CPL Pubid: 208878


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Institutioner (Chalmers)

Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium


Astronomi, astrofysik och kosmologi

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