Spectral and morphological analysis of the remnant of supernova 1987A with alma and atca

Giovanna Zanardo, Lister 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. Lakićević, P. Lundqvist, J.M. Márcaide, I. Martí-Vidal, M.M. Meixner, N. Chi Yung, S. Park, G. Sonneborn, J. SpyromilioJ.T.H. Van Loon

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    Abstract

    © 2014. The American Astronomical Society. All rights reserved.. 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 (S 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 ≲ α ≲ -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.
    Original languageEnglish
    Pages (from-to)82
    JournalThe Astrophysical Journal
    Volume796
    Issue number2
    DOIs
    Publication statusPublished - 2014

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