Detailed Analysis of the Stripped-Envelope Core-Collapse Type Ib/c Supernova SN 1996aq

Stripped-envelope supernovae (SESNe, Clocchiatti et al. 1996) are a subclass of core-collapse supernovae (CCSNe) resulting from the violent explosions of massive stars (15-50 M⊙ in the main sequence) that have lost most or all of their hydrogen (Types IIb, Ib) and possibly helium (Type Ic) envelopes prior to collapse. These events mark the end of the evolution of massive stars and play a crucial role in the chemical enrichment of the Universe, ejecting heavy elements such as oxygen and carbon, essential for organic chemistry and life, into the interstellar medium. SESNe also lead to the formation of compact remnants such as neutron stars or black holes and are potentially associated with long-duration gamma-ray bursts (GRBs). In this study, I present a detailed analysis of the Type Ib/c supernova SN 1996aq located in the spiral galaxy NGC 5584. The photometric analysis includes multi-band and bolometric light curves, and spectral energy distributions (SEDs) reconstruction, from which the temperature, photospheric radius, and total luminosity are derived. The temporal evolution of the photospheric radius and temperature, obtained through blackbody fits to the SEDs, are studied as a function of the phase since the first detection date. Explosion parameters such as ejecta mass, nickel mass, and kinetic energy are then estimated using Arnett’s rule (1982), following the methodology outlined by Prentice et al. (2016, 2019). The spectroscopic analysis includes the study of twelve spectra starting from three weeks after the explosion and up to the nebular phases. During the photospheric phase, detailed line identifications are carried out for the main ions, and the temporal evolution of their expansion velocities is followed. An estimate of the progenitor’s initial mass is then obtained by comparing, first, the luminosity of the [O I] λλ 6300, 6364 doublet normalised to the 56Co energy-deposition rate with the ones predicted by the models of Jerkstrand et al. (2015), and, second, the latest nebular spectrum with the nebular models of Jerkstrand et al. (2012) computed for different zero-age main-sequence masses of the progenitor star. Finally, the nebular [O I] λλ 6300, 6364 profile is examined and modelled using multiple Gaussian components, in order to test whether the doublet can be reproduced by a single oxygen-emitting region or instead requires additional components or asymmetries in the inner ejecta.