Detections of [O III] 88 mu m in two quasars in the reionization epoch

摘要

We report on detections with the Atacama Large Millimeter/sub-millimeter Array of the far-infrared [O III] 88 mu m line and the underlying dust continuum in two quasars in the reionization epoch, J205406.48-000514.8 (hereafter J2054-0005) at z = 6.0391 +/- 0.0002 and J231038.88+185519.7 (hereafter J2310+1855) at z = 6.0035 +/- 0.0007. The [O III] luminosities of J2054-0005 and J2310+1855 are L-[O III] = (6.8 +/- 0.6) x 10(9) and (2.4 +/- 0.6) x 10(9) L-circle dot, corresponding to similar to 0.05% and 0.01% of the total infrared luminosity, L-TIR, respectively. Combining these [O III] luminositieswith [C II] 158 mu m luminosities in the literature, we find that J2054-0005 and J2310+1855 have [O III]-to-[C II] luminosity ratios of 2.1 +/- 0.4 and 0.3 +/- 0.1, respectively, the latter of which is the lowest among objects so far reported at z > 6. Combining [O III] observations at z approximate to 6-9 from our study and the literature, we identify the [OIII] line deficit: objects with a larger L-TIR (total infrared luminosity) have lower L-[O III]-to-L-TIR ratios. Furthermore, we also find that the anti-correlation is shifted toward a higher L-TIR value when compared with the local [O III] line deficit.