Zanardo, Giovanna, Staveley-Smith, Lister, Indebetouw, Remy, Chevalier, Roger A., Matsuura, Mikako ![]() |
Abstract
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 (λ 3.2 mm to 450 μm), 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 (Sν∝ν−0.73) and the thermal component originating from dust grains at T ~ 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 lesssim α lesssim −0.1 across the western regions, with α ~ 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.
Item Type: | Article |
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Date Type: | Published Online |
Status: | Published |
Schools: | Physics and Astronomy |
Subjects: | Q Science > QB Astronomy |
Uncontrolled Keywords: | ISM: supernova remnants; radiation mechanisms: non-thermal; radiation mechanisms: thermal; radio continuum: general; stars: neutron; supernovae: individual (SN 1987A) |
Publisher: | IOP Science |
ISSN: | 0004-637X |
Date of Acceptance: | 26 September 2014 |
Last Modified: | 27 Oct 2022 10:22 |
URI: | https://orca.cardiff.ac.uk/id/eprint/69874 |
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