Evidence for Extended Hydrogen-Poor CSM in the Three-Peaked Light Curve of Stripped Envelope Ib Supernova

Zenati, Yossef and Wang, Qinan and Bobrick, Alexey and DeMarchi, Lindsay and Glanz, Hila and Rozner, Mor and Rest, Armin and Metzger, Brian D and Margutti, Raffaella and Gomez, Sebastian and Smith, Nathan and Toonen, Silvia and Bright, Joe S and Norman, Colin and Foley, Ryan J and Gagliano, Alexander and Krolik, Julian H and Smartt, Stephen J and Villar, Ashley V and Narayan, Gautham and Fox, Ori and Auchettl, Katie and Brethauer, Daniel and Clocchiatti, Alejandro and Coelln, Sophie V and Coppejans, Deanne L and Dimitriadis, Georgios and Doroszmai, Andris and Drout, Maria and Jacobson-Galan, Wynn and Gao, Bore and Ridden-Harper, Ryan and Kilpatrick, Charles Donald and Laskar, Tanmoy and Matthews, David and Rest, Sofia and Smith, Ken W and Stauffer, Candice McKenzie and Stroh, Michael C and Strolger, Louis-Gregory and Terreran, Giacomo and Pierel, Justin D R and Piro, Anthony L (2022) Evidence for Extended Hydrogen-Poor CSM in the Three-Peaked Light Curve of Stripped Envelope Ib Supernova. arXiv. ISSN 2331-8422

Abstract

We present multi-band ATLAS photometry for SN 2019tsf, a stripped-envelope Type Ib supernova (SESN). The SN shows a triple-peaked light curve and a late (re-)brightening, making it unique among stripped-envelope systems. The re-brightening observations represent the latest photometric measurements of a multi-peaked Type Ib SN to date. As late-time photometry and spectroscopy suggest no hydrogen, the potential circumstellar material (CSM) must be H-poor. Moreover, late (>150 days) spectra show no signs of narrow emission lines, further disfavouring CSM interaction. On the contrary, an extended CSM structure is seen through a follow-up radio campaign with Karl G. Jansky Very Large Array (VLA), indicating a source of bright optically thick radio emission at late times, which is highly unusual among H-poor SESNe. We attribute this phenomenology to an interaction of the supernova ejecta with spherically-asymmetric CSM, potentially disk-like, and we present several models that can potentially explain the origin of this rare Type Ib supernova. The warped disc model paints a novel picture, where the tertiary companion perturbs the progenitors CSM, that can explain the multi-peaked light curves of SNe, and here we apply it to SN 2019tsf. This SN 2019tsf is likely a member of a new sub-class of Type Ib SNe and among the recently discovered class of SNe that undergo mass transfer at the moment of explosion