A reddening-free method to estimate the⁵⁶Ni mass of Type Ia supernovae

Abstract

The increase in the number of Type Ia supernovae (SNe Ia) has demonstrated that the population shows greater diversity than has been assumed in the past. The reasons (e.g. parent population, explosion mechanism) for this diversity remain largely unknown. We investigated a sample of SNe Ia near-infrared light curves and correlated the phase of the second maximum with the bolometric peak luminosity. The peak bolometric luminosity is related to the time of the second maximum (relative to the B light curve maximum) as follows: L max (10 43 erg s −1 ) = (0.039 ± 0.004) × t 2 (J)(days) + (0.013 ± 0.106). 56 Ni masses can be derived from the peak luminosity based on Arnett's rule, which states that the luminosity at maximum is equal to the instantaneous energy generated by the nickel decay. We checked this assumption against recent radiative-transfer calculations of Chandrasekhar-mass delayed detonation models and find this assumption is valid to within 10% in recent radiative-transfer calculations of Chandrasekhar-mass delayed detonation models. The L max vs. t 2 relation is applied to a sample of 40 additional SNe Ia with significant reddening (E(B − V) > 0.1 mag), and a reddening-free bolometric luminosity function of SNe Ia is established. The method is tested with the 56 Ni mass measurement from the direct observation of γ-rays in the heavily absorbed SN 2014J and found to be fully consistent. Super-Chandrasekhar-mass explosions, in particular SN 2007if, do not follow the relations between peak luminosity and second IR maximum. This may point to an additional energy source contributing at maximum light. The luminosity function of SNe Ia is constructed and is shown to be asymmetric with a tail of low-luminosity objects and a rather sharp high-luminosity cutoff, although it might be influenced by selection effects.

Standardizing Type Ia supernovae optical brightness using near-infrared rebrightening time

“…They inferred that the diversity in t2 values of SNIa is driven by different masses of 56 Ni produced in the explosion. As a follow-up, Dhawan et al (2016) identified a strong correlation between the peak bolometric luminosity (Lmax) and t2 for a sample of SNIa with well-measured NIR data. Since the luminosity at peak corresponds to the instantaneous energy deposition rate from 56 Ni decay (known as " Arnett's Rule" Arnett 1982), the authors used the correlation between Lmax and t2 and Arnett's rule to infer a 56 Ni mass distribution.…”

“…Kasen (2006), based on radiative transfer calculations of synthetic lightcurves, predicted that t2 is a function of the 56 Ni mass produced by the SNIa. Indeed, Dhawan et al (2016) found a strong correlation between the peak bolometric luminosity (and therefore, 56 Ni mass, see Arnett 1982) and t2 for a sample of SNIa with low-extinction from host galaxy dust. They demonstrate that this parameter can be used to infer the 56 Ni mass for SNIa.…”

iPTF16abc and the population of Type Ia supernovae: comparing the photospheric, transitional, and nebular phases

“…The impact of this on further parameter estimation is discussed below. Assuming Arnett's rule is obeyed and a rise time of t R =19 days with an error of 3 days (Stritzinger et al 2006;Dhawan et al 2016), we can derive a M56 Ni from the computed value of L max :…”

“…These observations have been critical to derive global parameters for SNe Ia, e.g. synthesized 56 Ni mass, total ejecta mass (Stritzinger et al 2006;Scalzo et al 2014;Dhawan et al 2016Dhawan et al , 2017. However, there is a wealth of information available in observations shortly after explosion as well as at late times (∼ a year after maximum, i.e.…”

Nebular spectroscopy of SN 2014J: Detection of stable nickel in near-infrared spectra

“…Imaging of the supernova reveals the presence of clear echoes (Yang et al 2017). Estimates of the 56 Ni mass using the timing of the NIR second maximum (Dhawan et al 2016) and γ-ray observations (Churazov et al 2015) infer masses of 0.64 ± 0.13 M and 0.62 ± 0.13 M , respectively, consistent with the estimate for a normal SN Ia (Stritzinger et al 2006;Scalzo et al 2014). Optical spectra of SN 2014J in the nebular phase are remarkably similar to the 'normal' SNe 2011fe and 2012cg (Amanullah et al 2015).…”