Luminous Late-time Radio Emission from Supernovae Detected by the Karl G. Jansky Very Large Array Sky Survey (VLASS)

Michael C. Stroh, Giacomo Terreran, Deanne L. Coppejans, Joe S. Bright, Raffaella Margutti, Michael F. Bietenholz, Fabio De Colle, Lindsay Demarchi, Rodolfo Barniol Duran, Danny Milisavljevic, Kohta Murase, Kerry Paterson, Wendy L. Williams

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10 Scopus citations


We present a population of 19 radio-luminous supernovae (SNe) with emission reaching L ν ∼ 1026-1029 erg s-1 Hz-1 in the first epoch of the Very Large Array Sky Survey (VLASS) at 2-4 GHz. Our sample includes one long gamma-ray burst, SN 2017iuk/GRB 171205A, and 18 core-collapse SNe detected at ≈1-60 yr after explosion. No thermonuclear explosion shows evidence for bright radio emission, and hydrogen-poor progenitors dominate the subsample of core-collapse events with spectroscopic classification at the time of explosion (79%). We interpret these findings in the context of the expected radio emission from the forward shock interaction with the circumstellar medium (CSM). We conclude that these observations require a departure from the single wind-like density profile (i.e., ρ CSM ∝ r -2) that is expected around massive stars and/or from a spherical Newtonian shock. Viable alternatives include the shock interaction with a detached, dense shell of CSM formed by a large effective progenitor mass-loss rate, (Equation presented) yr-1 (for an assumed wind velocity of 1000 km s-1); emission from an off-axis relativistic jet entering our line of sight; or the emergence of emission from a newly born pulsar-wind nebula. The relativistic SN 2012ap that is detected 5.7 and 8.5 yr after explosion with L ν ∼ 1028 erg s-1 Hz-1 might constitute the first detections of an off-axis jet+cocoon system in a massive star. However, none of the VLASS SNe with archival data points are consistent with our model off-axis jet light curves. Future multiwavelength observations will distinguish among these scenarios. Our VLASS source catalogs, which were used to perform the VLASS cross-matching, are publicly available at

Original languageEnglish (US)
Article numberL24
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Dec 20 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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