Near-infrared light curves of Type Ia supernovae: Studying the properties of the second maximum

TL;DR

This study analyzes near-infrared light curves of 91 Type Ia supernovae to understand their uniformity and physical properties, revealing strong correlations between NIR maxima, optical features, and nickel mass synthesis.

Contribution

It provides a comprehensive analysis of NIR light curves, highlighting correlations that link supernova properties to explosion nickel mass, enhancing understanding of their uniformity and use as standard candles.

Findings

The phase and luminosity of the first NIR maximum are highly uniform.

Later second maximum phases correlate with higher luminosity and nickel mass.

Decline rates after the second maximum are very consistent across NIR filters.

Abstract

Type Ia supernovae have been proposed to be much better distance indicators at near-infrared compared to optical wavelengths -- the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the $Y$, $J$ and $H$-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs $\sim$ 15 to 30 days after $B$ band maximum). The decline rate after the second maximum is very uniform in all NIR filters. We suggest that these observational parameters are linked to the nickel and iron mass in the explosion, providing evidence that the amount of nickel synthesised in the explosion is the dominating factor shaping the optical and NIR appearance of SNe Ia.