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We modeled the radio non-detection of two Type Ia supernovae (SNe) 2011fe and 2014J considering synchrotron emission from the interaction between SN ejecta and the circumstellar medium. For an ejecta with the outer part having a power law density structure we compare synchrotron emission with radio observations. Assuming that 20$%$ of the bulk shock energy is being shared equally between electrons and magnetic fields we found a very low density medium around both the SNe. A less tenuous medium with particle density $sim$ 1 $rm cm^{-3}$, which could be expected around both SNe, can be estimated when the magnetic field amplification is less than that presumed for energy equipartition. This conclusion also holds if the progenitor of SN 2014J was a rigidly rotating white dwarf (WD) with a main sequence (MS) or red giant companion. For a He star companion, or a MS for SN 2014J, with 10$%$ and 1$%$ of bulk kinetic energy in magnetic fields, we obtain a mass loss rate $< 10^{-9}$ and $< sim 4times 10^{-9}$ M$_{odot}$yr$^{-1}$ for a wind velocity of 100 km/s. The former requires a mass accretion efficiency $>$ 99$%$ onto the WD, but is less restricted for the latter case. However, if the tenuous medium is due to a recurrent nova it is difficult from our model to predict synchrotron luminosities. Although the formation channels of SNe 2011fe and 2014J are not clear, the null detection in radio wavelengths could point toward a low amplification efficiency for magnetic fields in SN shocks.
Left-over, ablated material from a possible non-degenerate companion can reveal itself after about one year in spectra of Type Ia SNe (SNe Ia). We have searched for such material in spectra of SN 2011fe (at 294 days after the explosion) and for SN 20
The nearby, bright, almost completely unreddened Type Ia supernova 2011fe in M101 provides a unique opportunity to test both the precision and the accuracy of the extragalactic distances derived from SNe Ia light curve fitters. We apply the current, publ
Turbulent dynamo field amplification has often been invoked to explain the strong field strengths in thin rims in supernova shocks ($sim 100 , mu$G) and in radio relics in galaxy clusters ($sim mu$G). We present high resolution MHD simulations of the
The observational effects of the Infrared Catastrophe are discussed in view of the very late observations of the Type Ia SN 2011fe. Our model spectra at 1000d take non-local radiative transfer into account, and find that this has a crucial impact on
SN 2014J in M82 is the closest Type Ia supernova (SN Ia) in decades. The proximity allows for detailed studies of supernova physics and provides insights into the circumstellar and interstellar environment. In this work we analyze Spitzer mid-IR data