S21B0153
S21B0153
To investigate star formation history, nucleosynthesis, and supernova activity in the early universe, it is important to explore the evolution of the [Mg/Fe] abundance ratio through cosmic time. Here we propose near-infrared spectroscopic observation of 10 quasars at z ∼ 5 with SWIMS to estimate the [Mg/Fe] abundance ratio of the broad-line region from the Mg II λ2798 emission line and surrounding Fe II pseudo-continuum. In the past observation of z ∼ 5 quasars with Subaru+OHS, accurate estimation of the continuum was difficult due to the limited wavelength range, which left large systematic errors in the measurements and makes it practically impossible to test for the chemical evolution. This problem can be solved by using SWIMS, which has a wide wavelength coverage and can obtain continuously connected spectra without uncertainty due to slit loss. The [Mg/Fe] abundance ratio at z ∼ 5 is particularly important because it strongly depends on the lifetime of SNe Ia progenitors (tIa), and can be used to check whether the shorter tIa recently suggested by studies on the delay time distribution of SNe Ia is plausible. If the short tIa is confirmed to be plausible, it will provide new insights into the existence of large amounts of iron in the universe at a much earlier stage than previously thought.
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