Physical conditions of the interstellar medium in star-forming galaxies at z~1.5
Physical conditions of the interstellar medium in star-forming galaxies at z~1.5
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z~1.5 恒星形成星系中星际介质的物理条件
DOI：
10.1093/pasj/psv041
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发表时间：
2015
影响因子：
2.3
通讯作者：
Yoshiaki
中科院分区：
文献类型：
--
作者：
Hayashi;Masao; Ly;Chun; Shimasaku;Kazuhiro; Motohara;Kentaro; Malkan;Matthew A.; Nagao;Tohru; Kashikawa;Nobunari; Goto;Ryosuke; Naito;Yoshiaki
We present results from Subaru Fiber Multi Object Spectrograph near-infrared spectroscopy of 118 star-forming galaxies atz∼ 1.5 in the Subaru Deep Field. These galaxies are selected as [Oii]λ3727 emitters atz≈ 1.47 and 1.62 from narrow-band imaging. We detect the Hα emission line in 115 galaxies, the [Oiii]λ5007 emission line in 45 galaxies, and Hβ, [Nii]λ6584, and [Sii]λλ6716, 6731 in 13, 16, and 6 galaxies, respectively. Including the [Oii] emission line, we use the six strong nebular emission lines in the individual and composite rest-frame optical spectra to investigate the physical conditions of the interstellar medium in star-forming galaxies atz∼ 1.5. We find a tight correlation between Hα and [Oii], which suggests that [Oii] can be a good star formation rate indicator for galaxies atz∼ 1.5. The line ratios of Hα/[Oii] are consistent with those of local galaxies. We also find that [Oii] emitters have strong [Oiii] emission lines. The [Oiii]/[Oii] ratios are larger than normal star-forming galaxies in the local universe, suggesting a higher ionization parameter. Less massive galaxies have larger [Oiii]/[Oii] ratios. With evidence that the electron density is consistent with local galaxies, the high ionization of galaxies at high redshifts may be attributed to a harder radiation field by a young stellar population and/or an increase in the number of ionizing photons from each massive star.
