Outshining by Recent Star Formation Prevents the Accurate Measurement of High-z Galaxy Stellar Masses

Understand

In this paper, we demonstrate that the inference of galaxy stellar masses via spectral energy distribution (SED) fitting techniques for galaxies formed in the first billion years after the Big Bang carries fundamental uncertainties owing to the loss of star formation history (SFH) information from the very first episodes of star formation in the integrated spectra of galaxies.

• While this early star formation can contribute substantially to the total stellar mass of high-redshift systems, ongoing star formation at the time of detection outshines the residual light from earlier bursts, hampering the determination of accurate stellar masses.
• As a result, order of magnitude uncertainties in stellar masses can be expected.
• We demonstrate this potential problem via direct numerical simulation of galaxy formation in a cosmological context.