Browsing by Author "Zenati, Yossef"

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    SN 2019tsf: Evidence for Extended Hydrogen-poor CSM in the Three-peaked Light Curve of Stripped Envelope of a Type Ib Supernova
    (2025) Zenati, Yossef; Wang, Qinan; Bobrick, Alexey; DeMarchi, Lindsay; Glanz, Hila; Rozner, Mor; Jencson, Jacob E.; Rest, Armin; Metzger, Brian D.; Margutti, Raffaella; Gómez, Sebastián; Smith, Nathan; Toonen, Silvia; Bright, Joe S.; Norman, Colin; Foley, Ryan J.; Gagliano, Alexander; Krolik, Julian H.; Smartt, Stephen J.; Villar, Ashley V.; Narayan, Gautham; Fox, Ori; Auchettl, Katie; Brethauer, Daniel; Clocchiatti, Alejandro; Coelln, Sophie V.; Coppejans, Deanne L.; Dimitriadis, Georgios; Dorozsmai, Andris; Drout, Maria; Jacobson-Galan, Wynn; Gao, Bore; Ridden-Harper, Ryan; Kilpatrick, Charles Donald; Laskar, Tanmoy; Matthews, David; Smith, Ken W.; Stauffer, Candice McKenzie; Rest, Sofia; Stroh, Michael C.; Strolger, Louis-Gregory; Terreran, Giacomo; Pierel, Justin D. R.; Piro, Anthony L.
    We present multiband ATLAS and ZTF photometry for SN 2019tsf, a Type Ib stripped-envelope supernova (SESN). The slow spectral evolution could be associated with an uncommon explosion mechanism specific to this SN. Possible explanations include fallback accretion onto a compact remnant or a long-lived central engine, both of which could provide extended energy injection responsible for the late-time rebrightening and unusual spectral features. The rebrightening observations represent the latest photometric measurements of a multipeaked Type Ib SN. As late-time photometry and spectroscopy suggest no hydrogen, the potential circumstellar material (CSM) must be H-poor. The absence of a nebular phase and the lack of narrow emission lines in the late-time spectra (>142 days) of the SNe suggest that any CSM interaction is likely asymmetric and enveloped by the SN ejecta. However, an extended CSM structure is evident through a follow-up radio campaign with the 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 asymmetric CSM, potentially disk-like, and we present several models that may explain the origin of this rare Type Ib supernova. We propose a warped disk model in which a tertiary companion—commonly present around massive stars—perturbs the progenitor's CSM, producing density enhancements that may explain the observed multipeaked SN 2019tsf light curve. This SN 2019tsf is a unique SN Type Ib among the recently discovered class of SNe that undergo mass transfer at the moment of explosion....