Radio observations reveal a smooth circumstellar environment around the extraordinary type Ib supernova 2012au

Atish Kamble, Alicia M. Soderberg, Laura Chomiuk, Raffaella Margutti, Mikhail Medvedev, Dan Milisavljevic, Sayan Chakraborti, Roger Chevalier, Nikolai Chugai, Jason Dittmann, Maria Drout, Claes Fransson, Ehud Nakar, Nathan Sanders

Research output: Contribution to journalArticlepeer-review


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 (ρr -2). We infer a sub-relativistic velocity for the shock wave v 0.2 c and a radius of r 1.4 × 1016cm 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.

Original languageEnglish
Article number2
JournalAstrophysical Journal
Issue number1
StatePublished - 10 Dec 2014


  • radiation mechanisms: non-thermal
  • radio continuum: general
  • supernovae: general
  • supernovae: individual (SN 2012au)


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