Although Type Ia supernova cosmology has now reached a mature state , it is important to develop as many independent methods as possible to understand the true nature of dark energy .
Recent studies have shown that Type II supernovae ( SNe II ) offer such a path and could be used as alternative distance indicators .
However , the majority of these studies were unable to extend the Hubble diagram above redshift z = 0.3 because of observational limitations .
Here , we show that we are now ready to move beyond low redshifts and attempt high-redshift ( z \gtrsim 0.3 ) SN II cosmology as a result of new-generation deep surveys such as the Subaru/Hyper Suprime-Cam ( HSC ) survey .
Applying the ‘ ‘ standard candle method ’ ’ to SN 2016jhj ( z = 0.3398 \pm 0.0002 ; discovered by HSC ) together with a low-redshift sample , we are able to construct the highest-redshift SN II Hubble diagram to date with an observed dispersion of 0.27 mag ( i.e. , 12–13 % in distance ) .
This work demonstrates the bright future of SN II cosmology in the coming era of large , wide-field surveys like that of the Large Synoptic Survey Telescope .