EMPRESS. XV. A New Determination of the Primordial Helium Abundance Suggesting a Moderately Low $Y_{\mathrm{P}}$ Value

Hiroto Yanagisawa, Masami Ouchi, Akinori Matsumoto +18

We present a new constraint on the primordial helium abundance, $Y_{\mathrm{P}}$, based on Subaru observations. A major source of uncertainty in previous $Y_{\mathrm{P}}$ determination…