VLBA26B-244
The Radio Bright SN2025shf: Off-axis Jet or Circumstellar Material Interaction?
Abstract
Long-duration gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, visible out to cosmological redshifts. These jetted and relativistic explosions are typically associated with massive-star deaths (broad-lined Ic supernovae; SNe Ic-bl), however many SNe Ic-bl are detected with no GRB counterpart. One expectation is that these GRB-less SNe Ic-bl harbor off-axis jets. Years after the explosion, the off-axis jet will have decelerated and become spherical, resulting in a late-rising radio light curve. Alternative explanations for late-rising radio emission following SN Ic-bl include circumstellar medium (CSM) interaction, which has important implications for the evolution of the massive star progenitor. Here we propose to observe SN2025shf, a SN Ic-bl detected in July 2025, and detected both in VLASS Epoch 4 and in VLA DDT Observations. Compared to recent optical observations, the radio emission shows strong evidence of originating from an off-axis GRB. The best way to distinguish between an off-axis GRB and CSM interaction is through searching for superluminal motion with VLBI observations. Our requested VLA and VLBA/HSA observations will track the temporal and spectral evolution of SN2025shf, as well as track the size and position of the source, crucial for determining the origin of the radio emission.
Investigators
| Name | Institution |
|---|---|
| GBT Operator | Green Bank Observatory |
| Genevieve Schroeder * | Northwestern University; Cornell University; Toronto, University of |
| Anna Ho | National Radio Astronomy Observatory; California at Berkeley, University of; Cornell University; Massachusetts Institute of Technology; Max-Planck-Institut für Astronomie; California Institute of Technology |
| Ranadeep Ghosh Dastidar | Purdue University |
| Alessandra Corsi | Johns Hopkins University |
| Poonam Chandra | National Radio Astronomy Observatory; Tata Institute of Fundamental Research |
| Daniel Perley | Liverpool John Moores University; California Institute of Technology; Københavns Universitet |
| Tanner O'Dwyer | Johns Hopkins University; Texas Tech University |
| Raphael Baer-Way | Virginia, University of |
| Paul Duffell | Purdue University; Center for Astrophysics | Harvard & Smithsonian |
| Maryam Modjaz | Virginia, University of; New York University |
* indicates the PI