SN 2019vxm: A Shocking Coincidence between Fermi and TESS

Journal article

Shock breakout and, in some cases, jet-driven high-energy emission are increasingly recognized as key signatures of the earliest phases of core-collapse supernovae, especially in Type IIn systems due to their dense, interaction-dominated circumstellar environments. We present a comprehensive photometric analysis of SN 2019vxm, a long-duration, luminous Type IIn supernova, MV=−21.41±0.05mag , observed from X-ray to near-infrared. SN 2019vxm is the first superluminous supernovae Type IIn to be caught with well-sampled TESS photometric data on the rise and has a convincing coincident X-ray source at the time of first light. The high-cadence TESS light curve captures the early-time rise, which is well described by a broken power law with an index of n = 1.41 ± 0.04, significantly shallower than the canonical n = 2 behavior. From this, we constrain the time of first light to within 7.2 hr. We identify a spatial and temporal coincidence between SN 2019vxm and the hard X-ray/gamma-ray transient GRB 191117A, corresponding to a 3.3σ association confidence. Both the short-duration X-ray event and the lightcurve modeling are consistent with shock breakout into a dense, asymmetric circumstellar medium, indicative of a massive, compact progenitor such as a luminous blue variable transitioning to Wolf–Rayet phase embedded in a clumpy, asymmetric environment.

Authors: Lane, ZG; Ridden-Harper, R; Rest, S; Rest, A; Ransome, CL

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 1003
• Issue: 1
• Pages: 19
• Article number: 19
• Publication date: 2026-05-11
• Acceptance date: 2026-04-10
• DOI: 10.3847/1538-4357/ae6245
• EISSN: 1538-4357
• ISSN: 0004637X, 0004-637X
• Language: English
• Keywords: Transient sources; Supernovae; X-ray bursts; Core-collapse supernovae; High energy astrophysics