The Carnegie Supernova Project II

Early observations and progenitor constraints of the Type Ib supernova LSQ13abf^⋆,⋆⋆

¹ Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
e-mail: max@phys.au.dk
² Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 100, Norman, OK 73019-2061, USA
³ Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena, Chile
⁴ The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova 10691, Stockholm, Sweden
⁵ George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, Department of Physics and Astronomy, College Station, TX 77843, USA
⁶ Konkoly Observatory, CSFK, Konkoly-Thege M. ut 15-17, Budapest, Hungary
⁷ Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, Szeged, Hungary
⁸ Department of Astronomy, University of Texas, 1 University Station C1400, Austin, TX 78712, USA
⁹ Department of Physics, Florida State University, Tallahassee, FL 32306, USA
¹⁰ Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA
¹¹ Instituto de Astrofısica de La Plata (IALP), CONICET, Paseo del bosque s/n, 1900 La Plata, Argentina
¹² Facultad de Ciencias Astronómicas y Geofísicas (FCAG), Universidad Nacional de La Plata (UNLP), Paseo del bosque s/n, 1900 La Plata, Argentina
¹³ Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
¹⁴ Departamento de Física Teórica y del Cosmos, Universidad de Granada, 18071 Granada, Spain

Received: 3 September 2019
Accepted: 12 November 2019

Abstract

Supernova LSQ13abf was discovered soon after explosion by the La Silla-QUEST Survey and then followed by the Carnegie Supernova Project II at its optical and near-IR wavelengths. Our analysis indicates that LSQ13abf was discovered within two days of explosion and its first ≈10 days of evolution reveal a B-band light curve with an abrupt drop in luminosity. Contemporaneously, the V-band light curve exhibits a rise towards a first peak and the r- and i-band light curves show no early peak. The early light-curve evolution of LSQ13abf is reminiscent of the post-explosion cooling phase observed in the Type Ib SN 2008D, and the similarity between the two objects extends over weeks. Spectroscopically, LSQ13abf also resembles SN 2008D, with P Cygni He I features that strengthen over several weeks. Spectral energy distributions are constructed from the broad-bandphotometry, a UVOIR light curve is constructed by fitting black-body (BB) functions, and the underlying BB-temperature and BB-radius profiles are estimated. Explosion parameters are estimated by simultaneously fitting an Arnett model to the UVOIR light curve and the velocity evolution derived from spectral features, and an in addition to a post-shock breakout cooling model to the first two epochs of the bolometric evolution. This combined model suggests an explosion energy of 1.27 ± 0.23 × 10⁵¹ ergs, in addition to a relatively high ejecta mass of 5.94 ± 1.10 M_⊙, a ⁵⁶Ni mass of 0.16 ± 0.02 M_⊙, and a progenitor-star radius of 28.0 ± 7.5 R_⊙. The ejecta mass suggests the origins of LSQ13abf lie with a > 25 M_⊙ zero-age-main-sequence mass progenitor and its estimated radius is three times larger compared to the result obtained from the same analysis applied to observations of SN 2008D, and nine times larger compared to SN 1999ex. Alternatively, a comparison of hydrodynamical simulations of ≳20−25 M_⊙ zero-age-main-sequence progenitors that evolve to pre-supernova envelope masses of ≲10 M_⊙ and extended (∼100 R_⊙) envelopes also broadly match the observations of LSQ13abf.