Speaker
Suhail Dhawan
(ESO)
Description
Type Ia supernovae have been proposed as much better distance indicators at near-infrared
compared to optical wavelengths – the e ect of dust extinction is expected to be lower and it
has been shown that SNe Ia behave more like ‘standard candles’ at near-infrared 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 near-infrared light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase near-infrared 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 near-infrared filters at a later phase compared to fainter objects. The decline rate after the second maximum is very uniform in all near-infrared filters. 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 (referred to a tL). 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 near-infrared appearance of SNe Ia.
