2022ApJ...934..186N -
Astrophys. J., 934, 186 (2022/August-1)
Radio Evolution of a Type IIb Supernova SN 2016gkg.
NAYANA A.J., CHANDRA P., KRISHNA A. and ANUPAMA G.C.
Abstract (from CDS):
We present extensive radio monitoring of a Type IIb supernova (SN IIb), SN 2016gkg during t ∼ 8-1429 days postexplosion at frequencies ν ∼ 0.33-25 GHz. The detailed radio light curves and spectra are broadly consistent with self-absorbed synchrotron emission due to the interaction of the SN shock with the circumstellar medium. The model underpredicts the flux densities at t ∼ 299 days postexplosion by a factor of 2, possibly indicating a density enhancement in the circumstellar medium due to a nonuniform mass loss from the progenitor. Assuming a wind velocity vw ∼ 200 km s–1, we estimate the mass-loss rate to be $\dot{M}\sim $ (2.2, 3.6, 3.8, 12.6, 3.7, and 5.0) ×10–6M⊙ yr–1 during ∼8, 15, 25, 48, 87, and 115 yr, respectively, before the explosion. The shock wave from SN 2016gkg is expanding from R ∼ 0.5 × 1016 to 7 × 1016 cm during t ∼ 24-492 days postexplosion indicating a shock deceleration index, m ∼ 0.8 (R ∝ tm), and mean shock velocity v ∼ 0.1c. The radio data are inconsistent with a free-free absorption model and higher shock velocities are in support of a relatively compact progenitor for SN 2016gkg.
Abstract Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Supernovae - Circumstellar matter - Radio continuum emission
Simbad objects:
20
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