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Radially Sampling the Circumstellar Material around Type Ia SN 2012cg with VLA Monitoring

ATel #4453; L. Chomiuk (Michigan State/NRAO), A. Soderberg (Harvard), J. Simon (Carnegie), and R. Foley (Harvard)
on 5 Oct 2012; 02:45 UT
Credential Certification: Laura Chomiuk (chomiuk@pa.msu.edu)

Subjects: Radio, Supernovae

We report radio monitoring of the nearby Type Ia SN 2012cg (CBET #3111) with the Karl G. Jansky Very Large Array (VLA). Our four epochs were observed approximately once per month, spanning 2012 May 19.1 to 2012 August 25.9. These radio observations were concurrent with our intensive multi-epoch program to obtain high-resolution optical spectroscopy of this SN with Magellan and MMT. Together, deep radio continuum observations and searches for time-variable optical absorption lines can constrain the density and radial distribution of circumstellar material around Type Ia SNe.

Our four epochs of VLA observations yielded deep limits on the 5.9 GHz radio flux density, with rms noise levels of 6 microJy/beam. These non-detections imply that if circumstellar material is present around SN 2012cg, it is located at a radius, > few times 10^16 cm, or it is distributed in thin shells of width ~< 10^15 cm. Further coordinated VLA monitoring of SN 2012cg is scheduled over the upcoming months to further constrain the distribution of circumstellar material. We thank the NRAO staff for approving these Rapid Response observations.