Near-infrared light curves of type Ia supernovae

TL;DR

This study uses a time-dependent model to simulate near-infrared light curves of Type Ia supernovae, confirming the role of IR line scattering and element recombination in the secondary maximum phenomenon.

Contribution

It demonstrates the importance of IR line scattering and element recombination in modeling SN Ia near-infrared light curves, highlighting the need for detailed NLTE effects.

Findings

IR line scattering is crucial for accurate light curve modeling.

Recombination of Fe III to Fe II and Co III to Co II causes the secondary maximum.

Models fit observed light curves reasonably well with parameter adjustments.

Abstract

Aims. With our time-dependent model atmosphere code PHOENIX, our goal is to simulate light curves and spectra of hydrodynamical models of all types of supernovae. In this work, we simulate near-infrared light curves of SNe Ia and confirm the cause of the secondary maximum. Methods. We apply a simple energy solver to compute the evolution of an SN Ia envelope during the free expansion phase. Included in the solver are energy changes due to expansion, the energy deposition of {\gamma}-rays and interaction of radiation with the material. Results. We computed theoretical light curves of several SN Ia hydrodynamical models in the I, J, H, and K bands and compared them to the observed SN Ia light curves of SN 1999ee and SN 2002bo. By changing a line scattering parameter in time, we obtained quite reasonable fits to the observed near-infrared light curves. This is a strong hint that detailed NLTE effects in IR lines have to be modeled, which will be a future focus of our work. Conclusions. We found that IR line scattering is very important for the near-infrared SN Ia light curve modeling. In addition, the recombination of Fe III to Fe II and of Co III to Co II is responsible for the secondary maximum in the near-infrared bands. For future work the consideration of NLTE for all lines (including the IR subordinate lines) will be crucial.