1. RADIO OBSERVATIONS REVEAL A SMOOTH CIRCUMSTELLAR ENVIRONMENT AROUND THE EXTRAORDINARY TYPE Ib SUPERNOVA 2012au.
- Author
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Kamble, Atish, Soderberg, Alicia M., Chomiuk, Laura, Margutti, Raffaella, Medvedev, Mikhail, Milisavljevic, Dan, Chakraborti, Sayan, Chevalier, Roger, Chugai, Nikolai, Dittmann, Jason, Drout, Maria, Fransson, Claes, Nakar, Ehud, and Sanders, Nathan
- Subjects
CIRCUMSTELLAR matter ,SUPERNOVAE ,CATACLYSMIC variable stars ,BINARY stars - Abstract
We present extensive radio and X-ray observations of SN 2012au, an energetic, radio-luminous supernova of Type Ib that exhibits multi-wavelength properties bridging subsets of hydrogen-poor superluminous supernovae, hypernovae, and normal core-collapse supernovae. The observations closely follow models of synchrotron emission from a shock-heated circumburst medium that has a wind density profile (ρ∝r
–2 ). We infer a sub-relativistic velocity for the shock wave v ≈ 0.2 c and a radius of r ≈ 1.4 × 1016 cm at 25 days after the estimated date of explosion. For a wind velocity of 1000 km s–1 , we determine the mass-loss rate of the progenitor to be , consistent with the estimates from X-ray observations. We estimate the total internal energy of the radio-emitting material to be E ≈ 1047 erg, which is intermediate to SN 1998bw and SN 2002ap. The evolution of the radio light curve of SN 2012au is in agreement with its interaction with a smoothly distributed circumburst medium and the absence of stellar shells ejected from previous outbursts out to r ≈ 1017 cm from the supernova site. We conclude that the bright radio emission from SN 2012au was not dissimilar from other core-collapse supernovae despite its extraordinary optical properties, and that the evolution of the SN 2012au progenitor star was relatively quiet, marked with a steady mass loss, during the final years preceding explosion. [ABSTRACT FROM AUTHOR]- Published
- 2014
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