| 1. |
- Zanardo, G., et al.
(author)
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Spectral and Morphological Analysis of the Remnant of Supernova 1987A with ALMA and ATCA
- 2014
-
In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 796:2, s. Art. no. 82-
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Journal article (peer-reviewed)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 (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.
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| 2. |
- Zanardo, Giovanna, et al.
(author)
-
SPECTRAL AND MORPHOLOGICAL ANALYSIS OF THE REMNANT OF SUPERNOVA 1987A WITH ALMA AND ATCA
- 2014
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 796:2
-
Journal article (peer-reviewed)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 (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.
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