Spectral and Morphological Analysis of the Remnant of Supernova 1987A with ALMA and ATCA
Journal article, 2014
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.
radiation mechanisms: thermal
ISM: supernova remnants
radio continuum: general
supernovae: individual (SN 1987A)
stars: neutron
radiation mechanisms: non-thermal
Author
G. Zanardo
University of Western Australia
L. Staveley-Smith
Centre of Excellence for All-sky Astrophysics (CAASTRO
University of Western Australia
R. Indebetouw
National Radio Astronomy Observatory
University of Virginia
R. Chevalier
University of Virginia
M. Matsuura
UCL
B. Gaensler
Centre of Excellence for All-sky Astrophysics (CAASTRO
The University of Sydney
M. J. Barlow
UCL
C. Fransson
Stockholms universitet
R. N. Manchester
Australia Telescope National Facility
Maarten Baes
Universiteit Gent
J. Kamenetzky
University of Arizona
M. Lakicevic
Keele University
P. Lundqvist
Stockholms universitet
J. M. Marcaide
Donostia International Physics Center
Universitat de ValEncia
Ivan Marti-Vidal
Chalmers, Earth and Space Sciences, Onsala Space Observatory
M. Meixner
STScI
Johns Hopkins University
C. Y. Ng
The University of Hong Kong
S. Park
University of Texas at Arlington
G. Sonneborn
NASA Goddard Space Flight Center
J. Spyromilio
European Southern Observatory
J. T. van Loon
Keele University
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 796 2 Art. no. 82- 82Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1088/0004-637x/796/2/82