The Late-Time Radio Spectrum of SN1993J

Abstract

We present VLA radio continuum measurements of SN1993J in M81 at the frequencies of 0.32 (P-band), 1.3 and 1.7 (L-band), 4.9 (C-band), 8.5 (X-band), and 14.9 (U-band) GHz carried out on December 17 and 21, 2000, about 2820 days after the supernova explosion. We find that a power-law spectrum, free-free absorbed by an homogeneous, or clumpy, distribution of ionized gas yields the best fit to the radio data. A combined homogeneous-clumpy model is not favored, but neither totally excluded. This result contrasts with the modeling of the early ($t \lessim $230 days) radio emission from SN1993J, where a mixture of homogeneous and clumpy absorbers appeared to be necessary to adequately describe the behavior of the light curves. The radio spectrum of supernova SN1993J between 0.32 and 14.9 GHz is well characterized by $\alpha =-0.67\pm 0.02$ ($S_{\nu }\propto {\nu }^{\alpha }$), typical of an optically thin radio supernova. A fit to the radio spectra of SN1993J from $\sim$ 70 up to 2820 days shows that the observed spectral index of SN1993J has been slowly evolving since $t\sim$1000 days on, with the observed spectral index changing from $\alpha \approx -1$ to $\alpha =-0.67$. This spectral evolution seems to suggest that, in addition to the radiative (synchrotron) losses, adiabatic cooling and ionization (Coulomb) losses at the lowest frequencies might be contributing significantly to the integrated electron spectrum.

A&A Main Journal, in press, 6 pages. Includes minor revisions

References in corpus (3)

• Simulated Radio Images and Light Curves of Young Supernovae
• X-Ray Detection of a Pre-Supernova Evolution for the SN 1993J Progenitor
• The role of synchrotron self-absorption in the late radio emission of SN1993J

Cited by in corpus (12)

• The late time radio emission from SN 1993J at meter wavelengths
• Long Term Radio Monitoring of SN 1993J
• A Decade of SN1993J: Discovery of Wavelength Effects in the Expansion Rate
• Discovery of a bright radio transient in M82: a new radio supernova?
• Radio emission of SN1993J. The complete picture: II. Simultaneous fit of expansion and radio light curves
• VLBI observations of SN 2008iz: I. Expansion velocity and limits on anisotropic expansion
• Evolution of the progenitors of SNe 1993J and 2011dh revealed through late time radio and X-ray studies
• Shell revealed in SN 1979C
• Synchrotron aging and the radio spectrum of SN 1993J
• The radio evolution of supernova SN2008iz in M82
• Modeling the Radio and X-ray Emission of SN 1993J and SN 2002ap
• Simulated Radio Images and Light Curves of SN 1993J