The remnant of supernova 1987A resolved at 3-mm wavelength⋆
European Organization for Astronomical Research in the Southern Hemisphere
(ESO), Karl-Schwarzschild-Str. 2,
Garching b. München,
2 Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK
3 International Centre for Radio Astronomy Research (ICRAR), M468, University of Western Australia, Crawley, WA 6009, Australia
4 Department of Physics, McGill University, Montréal, QC H3A 2T8, Canada
5 Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia
6 ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Australia
Received: 27 January 2012
Accepted: 22 March 2012
Context. The proximity of core-collapse supernova 1987A (SN 1987A) in the Large Magellanic Cloud (LMC) and its rapid evolution make it a unique case study of the development of a young supernova remnant.
Aims. We aim at resolving the remnant of SN 1987A for the first time in the 3-mm band (at 94 GHz).
Methods. We observed the source at 3-mm wavelength with a 750-m configuration of the Australia Telescope Compact Array (ATCA). We compared the image with a recent 3-cm image and with archival X-ray images.
Results. We present a diffraction-limited image with a resolution of 0.′′7, revealing the ring structure seen at lower frequencies and at other wavebands. The emission peaks in the eastern part of the ring. The 3-mm image bears resemblance to early X-ray images (from 1999–2000). We place an upper limit of 1 mJy (2σ) on any discrete source of emission in the centre (inside of the ring). The integrated flux density at 3 mm has doubled over the six years since the previous observations at 3 mm.
Conclusions. At 3 mm – i.e. within the operational domain of the Atacama Large Millimeter/submillimeter Array (ALMA) – SN 1987A appears to be dominated by synchrotron radiation from the inner rim of the equatorial ring, characterised by moderately weak shocks. There is no clear sign of emission of a different nature, but the current limits do not rule out such component altogether.
Key words: ISM: supernova remnants / radio continuum: ISM / Magellanic Clouds / supernovae: individual: SN 1987A
The processed data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/541/L2
© ESO, 2012