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Date and Time of the Query: 2019-08-17 T17:40:35 PDT
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For refcode 2011ApJ...740...95B:
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Copyright by American Astronomical Society. Reproduced by permission
2011ApJ...740...95B Resolution of the Compact Radio Continuum Sources in Arp220 Batejat, Fabien; Conway, John E.; Hurley, Rossa; Parra, Rodrigo; Diamond, Philip J.; Lonsdale, Colin J.; Lonsdale, Carol J. Abstract. We present 2 cm and 3.6 cm wavelength very long baseline interferometry images of the compact radio continuum sources in the nearby ultra-luminous infrared galaxy Arp220. Based on their radio spectra and variability properties, we confirm these sources to be a mixture of supernovae (SNe) and supernova remnants (SNRs). Of the 17 detected sources we resolve 7 at both wavelengths. The SNe generally only have upper size limits. In contrast all the SNRs are resolved with diameters >=0.27 pc. This size limit is consistent with them having just entered their Sedov phase while embedded in an interstellar medium (ISM) of density 10^4^ cm^-3^. These objects lie on the diameter-luminosity correlation for SNRs (and so also on the diameter-surface brightness relation) and extend these correlations to very small sources. The data are consistent with the relation Lv{prop}D ^-9/4^. Revised equipartition arguments adjusted to a magnetic field to a relativistic particle energy density ratio of 1% combined with a reasonable synchrotron-emitting volume filling factor of 10% give estimated magnetic field strengths in the SNR shells of ~15-50 mG. The SNR shell magnetic fields are unlikely to come from compression of ambient ISM fields and must instead be internally generated. We set an upper limit of 7 mG for the ISM magnetic field. The estimated energy in relativistic particles, 2%-20% of the explosion kinetic energy, is consistent with estimates from models that fit the IR-radio correlation in compact starburst galaxies. Key words: galaxies: individual: Arp220, galaxies: starburst, ISM: supernova remnants
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