Type II-P supernovae as standardised candles: improvements using near infrared data

Abstract

We present the first near infrared Hubble diagram for type II-P supernovae to further explore their value as distance indicators. We use a modified version of the standardised candle method which relies on the tight correlation between the absolute magnitudes of type II-P supernovae and their expansion velocities during the plateau phase. Although our sample contains only 12 II-P supernovae and they are necessarily local (z < 0.02), we demonstrate using near infrared JHK photometry that it may be possible to reduce the scatter in the Hubble diagram to 0.1-0.15 magnitudes. While this is potentially similar to the dispersion seen for type Ia supernovae, we caution that this needs to be confirmed with a larger sample of II-P supernovae in the Hubble flow.