Type Ic supernovae from the (intermediate) Palomar Transient Factory

Abstract

Context. Type Ic supernovae represent the explosions of the most stripped massive stars, but their progenitors and explosion mechanisms remain unclear. Larger samples of observed supernovae can help characterize the population of these transients. Aims. We present an analysis of 44 spectroscopically normal Type Ic supernovae, with focus on the light curves. The photometric data were obtained over 7 years with the Palomar Transient Factory and its continuation, the intermediate Palomar Transient Factory. This is the first homogeneous and large sample of SNe Ic from an untargeted survey, and we aim to estimate explosion parameters for the sample. Methods. We present K-corrected Bgriz light curves of these SNe, obtained through photometry on template-subtracted images. We performed an analysis on the shape of the r-band light curves and confirmed the correlation between the rise parameter Δm₋₁₀ and the decline parameter Δm₁₅. Peak r-band absolute magnitudes have an average of −17.71 ± 0.85 mag. To derive the explosion epochs, we fit the r-band lightcurves to a template derived from a well-sampled light curve. We computed the bolometric light curves using r and g band data, g − r colors and bolometric corrections. Bolometric light curves and Fe II λ5169 velocities at peak were used to fit to the Arnett semianalytic model in order to estimate the ejecta mass M_(ej), the explosion energy E_K and the mass of radioactive nickel M(⁵⁶Ni) for each SN. Results. Including 41 SNe, we find average values of ⟨M_(ej)⟩ = 4.50 ± 0.79 M⊙, ⟨E_K⟩ = 1.79 ± 0.29 × 10⁵¹ erg, and ⟨M⁵⁶Ni⟩ = 0.19 ± 0.03 M⊙. The explosion-parameter distributions are comparable to those available in the literature, but our large sample also includes some transients with narrow and very broad light curves leading to more extreme ejecta masses values.

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