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We present the results of a study which uses spectral energy distribution (SED) fitting to investigate the evolution of the equivalent width (EW) of the Hα emission line in star-forming galaxies over the redshift interval 1 z z 1. 3 with EW (Hα) measurements from 3D-HST grism spectroscopy, we proceed to apply our technique to samples of spectroscopically confirmed and photometric-redshift selected star-forming galaxies at z ≥ 1 in the CANDELS (Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey) UDS and GOODS-S fields. Confining our analysis to a constant stellar mass range (9. 5 M/M) A by redshift z 4. 5. Furthermore, using estimates of star formation rate (SFR) based on both UV luminosity and Hα line flux, we use our galaxy samples to compare the evolution of EW (Hα) and specific star formation rate (sSFR). Our results indicate that over the redshift range 1 z z) 1. 0 ± 0. 2. As a consequence, over this redshift range, we find that the sSFR and rest-frame EW (Hα) of star-forming galaxies with stellar masses M \ \\, 10^10\\, \ M{\ } are related by EW (Hα) /A = (63 ± 7) × sSFR/Gyr−1. Given the current uncertainties in measuring the SFRs of high-redshift galaxies, we conclude that EW (Hα) provides a useful independent tracer of sSFR for star-forming galaxies out to redshifts of z = 5.
Mármol-Queraltó et al. (Fri,) studied this question.