SN 2016jhj at redshift 0.34: extending the Type II supernova Hubble diagram using the standard candle method

Although Type Ia supernova cosmology has now reached a mature state, it is\nimportant to develop as many independent methods as possible to understand the\ntrue nature of dark energy. Recent studies have shown that Type II supernovae\n(SNe II) offer such a path and could be used as alternative distance\nindicators. However, the majority of these studies were unable to extend the\nHubble diagram above redshift $z=0.3$ because of observational limitations.\nHere, we show that we are now ready to move beyond low redshifts and attempt\nhigh-redshift ($z \\gtrsim 0.3$) SN~II cosmology as a result of new-generation\ndeep surveys such as the Subaru/Hyper Suprime-Cam (HSC) survey. Applying the\n"standard candle method" to SN$\\sim$2016jhj ($z=0.3398 \\pm 0.0002$; discovered\nby HSC) together with a low-redshift sample, we are able to construct the\nhighest-redshift SN II Hubble diagram to date with an observed dispersion of\n0.27 mag (i.e., 12-13% in distance). This work demonstrates the bright future\nof SN~II cosmology in the coming era of large, wide-field surveys like that of\nthe Large Synoptic Survey Telescope.\n