| Description: |
We present optical, radio, and X-ray observations of EP250108a/SN 2025kg, a broad-line Type Ic supernova (SN Ic-BL) accompanying an Einstein Probe (EP) fast X-ray transient at z = 0.176. EP250108a/SN 2025kg possesses a double-peaked optical light curve, and its spectrum transitions from a blue underlying continuum to a typical SN Ic-BL spectrum over time. We fit a radioactive decay model to the second peak of the optical light curve and find SN parameters that are consistent with the SN Ic-BL population, while its X-ray and radio properties are consistent with those of low-luminosity GRB (LLGRB) 060218/SN 2006aj. We explore three scenarios to understand the system’s multiwavelength emission: (a) SN ejecta interacting with an extended circumstellar medium (CSM), (b) the shocked cocoon of a collapsar-driven jet choked in its stellar envelope, and (c) the shocked cocoon of a collapsar-driven jet choked in an extended CSM. Models (b) and (c) can explain the optical light curve and are also consistent with the radio and X-ray observations. We favor model (c) because it can self-consistently explain both the X-ray prompt emission and first optical peak, but we do not rule out model (b). From the properties of the first peak in model (c), we find evidence that EP250108a/SN 2025kg interacts with an extended CSM and infer an envelope mass Me ∼ 0.1 M⊙ and radius Re ∼ 4 × 1013 cm. EP250108a/SN 2025kg’s multiwavelength properties make it a close analog to LLGRB 060218/SN 2006aj and highlight the power of early follow-up observations in mapping the environments of massive stars prior to core collapse. |
| Relation: |
https://researchonline.ljmu.ac.uk/id/eprint/26887/8/EP250108a%20SN%202025kg%20A%20Jet-driven%20Stellar%20Explosion%20Interacting%20with%20Circumstellar%20Material.pdf; Srinivasaragavan, GP ORCID logoorcid:0000-0002-6428-2700 , Hamidani, H ORCID logoorcid:0000-0003-2866-4522 , Schroeder, G ORCID logoorcid:0000-0001-9915-8147 , Sarin, N ORCID logoorcid:0000-0003-2700-1030 , Ho, AYQ ORCID logoorcid:0000-0002-9017-3567 , Piro, AL ORCID logoorcid:0000-0001-6806-0673 , Cenko, SB ORCID logoorcid:0000-0003-1673-970X , Anand, S ORCID logoorcid:0000-0003-3768-7515 , Sollerman, J ORCID logoorcid:0000-0003-1546-6615 , Perley, DA ORCID logoorcid:0000-0001-8472-1996 , Maeda, K ORCID logoorcid:0000-0003-2611-7269 , O’Connor, B ORCID logoorcid:0000-0002-9700-0036 , Kuncarayakti, H ORCID logoorcid:0000-0002-1132-1366 , Miller, MC ORCID logoorcid:0000-0002-2666-728X , Ahumada, T ORCID logoorcid:0000-0002-2184-6430 , Vail, JL ORCID logoorcid:0009-0000-4044-8799 , Duffell, P ORCID logoorcid:0000-0001-7626-9629 , Dastidar, R ORCID logoorcid:0009-0000-6548-6177 , Andreoni, I ORCID logoorcid:0000-0002-8977-1498 , Bochenek, A ORCID logoorcid:0009-0008-2714-2507 , Brennan, SJ ORCID logoorcid:0000-0003-1325-6235 , Carney, J ORCID logoorcid:0000-0001-8544-584X , Chen, P ORCID logoorcid:0000-0003-0853-6427 , Freeburn, J ORCID logoorcid:0009-0006-7990-0547 , Gal-Yam, A ORCID logoorcid:0000-0002-3653-5598 , Jacobson-Galán, W ORCID logoorcid:0000-0003-1103-3409 , Kasliwal, MM ORCID logoorcid:0000-0002-5619-4938 , Li 李, J嘉 ORCID logoorcid:0000-0001-9592-4190 , Li, ML ORCID logoorcid:0009-0001-6911-9144 , Sravan, N and Warshofsky, DE (2025) EP250108a/SN 2025kg: A Jet-driven Stellar Explosion Interacting with Circumstellar Material. The Astrophysical Journal Letters, 988 (2). ISSN 2041-8205 |