2019A&A...621A..71T

We study 34 Type Ic supernovae that have broad spectral features (SNe Ic-BL). This is the only SN type found in association with long-duration gamma-ray bursts (GRBs). We obtained our photometric data with the Palomar Transient Factory (PTF) and its continuation, the intermediate PTF (iPTF). This is the first large, homogeneous sample of SNe Ic-BL from an untargeted survey. Furthermore, given the high observational cadence of iPTF, most of these SNe Ic-BL were discovered soon after explosion. We present K-corrected Bgriz light curves of these SNe, obtained through photometry on template-subtracted images. We analyzed the shape of the r-band light curves, finding a correlation between the decline parameter Δm₁₅ and the rise parameter Δm_–10. We studied the SN colors and, based on g-r, we estimated the host-galaxy extinction for each event. Peak r-band absolute magnitudes have an average of -18.6±0.5mag. We fit each r-band light curve with that of SN 1998bw (scaled and stretched) to derive the explosion epochs. We computed the bolometric light curves using bolometric corrections, r-band data, and g-r colors. Expansion velocities from FeII were obtained by fitting spectral templates of SNe Ic. Bolometric light curves and velocities at peak were fitted using the semianalytic Arnett model to estimate ejecta mass M_ej, explosion energy E_K and ⁵⁶Ni mass M(⁵⁶Ni) for each SN. We find average values of M_ej=4±3M_☉, E_K=(7±6)x10⁵¹erg, and M(⁵⁶Ni)=0.31±0.16M_☉. The parameter distributions were compared to those presented in the literature and are overall in agreement with them. We also estimated the degree of ⁵⁶Ni mixing using scaling relations derived from hydrodynamical models and we find that all the SNe are strongly mixed. The derived explosion parameters imply that at least 21% of the progenitors of SNe Ic-BL are compatible with massive (>28M_☉), possibly single stars, whereas at least 64% might come from less massive stars in close binary systems.