论文标题
MOSDEF调查：对$ Z \ SIM 2.3 $星形星系的静止光发射线特性的全面分析
The MOSDEF Survey: A Comprehensive Analysis of the Rest-optical Emission-line Properties of $z\sim 2.3$ Star-forming Galaxies
论文作者
论文摘要
我们分析了整个Mosfire深层进化场（MOSDEF）调查中$ z \ sim2.3 $ SIM22.3 $ sim2.3的静止光发射线光谱。在研究[O III] 5008/h $β$ vs. [n ii] 6585/h $α$（“ [[n ii] bpt''）图中，高红移和本地星系序列之间的众所周知偏移的起源，我们定义了两个$ z \ sim2.3 $ mosd.3 $ mosdefeffalaxies。其中包括相对于局部SDSS序列和SDSS序列重叠的较高[O III] 5008/h $β$和/或[N II] 6585/H $α$的“高”人群。这两组也在[O III] 5008/H $β$中隔离，而[S ii] 6718,6733/h $α$和[O III] 4960,5008/[O II] 3727,3730（O $ $ $ _ {32} $）VS.（O $ _ {32} $） ii] 3727,3730）/h $β$（r $ _ {23} $）图，这表明在固定的偏移星系中，恒星形成区域的特征是在固定的含铁氧气中的较难电离光谱。我们还研究了分裂样品的许多星系特性，发现“高”样品的大小平均较小，质量较小，但具有较高的特异性恒星形成速率和恒星形成率的表面密度值，并且与“低”种群相比，它略年轻。从多云+BPASS光电离世模型中，我们估计“高”种群具有较低的恒星金属性（即更硬的电离频谱），但与“低”种群相比，烟囱金属性和更高的电离参数较高。虽然“高”人群比“低”人口更高$α$增强（即$α$/fe），但与局部恒星形成的星系相比，这两个样本的增强$ $α$的增强率明显高得多。这些差异必须在所有高红移星系星系中解释，而不仅仅是局部激发序列的“偏移”。
We analyze the rest-optical emission-line spectra of $z\sim2.3$ star-forming galaxies in the complete MOSFIRE Deep Evolution Field (MOSDEF) survey. In investigating the origin of the well-known offset between the sequences of high-redshift and local galaxies in the [O III]5008/H$β$ vs. [N II]6585/H$α$ ("[N II] BPT") diagram, we define two populations of $z\sim2.3$ MOSDEF galaxies. These include the "high" population that is offset towards higher [O III]5008/H$β$ and/or [N II]6585/H$α$ with respect to the local SDSS sequence and the "low" population that overlaps the SDSS sequence. These two groups are also segregated within the [O III]5008/H$β$ vs. [S II]6718,6733/H$α$ and the [O III]4960,5008/[O II]3727,3730 (O$_{32}$) vs. ([O III]4960,5008+[O II]3727,3730)/H$β$ (R$_{23}$) diagram, which suggests qualitatively that star-forming regions in the more offset galaxies are characterized by harder ionizing spectra at fixed nebular oxygen abundance. We also investigate many galaxy properties of the split sample and find that the "high" sample is on average smaller in size and less massive, but has higher specific star-formation rate and star-formation-rate surface density values and is slightly younger compared to the "low" population. From Cloudy+BPASS photoionization models, we estimate that the "high" population has a lower stellar metallicity (i.e., harder ionizing spectrum) but slightly higher nebular metallicity and higher ionization parameter compared to the "low" population. While the "high" population is more $α$-enhanced (i.e., higher $α$/Fe) than the "low" population, both samples are significantly more $α$-enhanced compared to local star-forming galaxies with similar rest-optical line ratios. These differences must be accounted for in all high-redshift star-forming galaxies -- not only those "offset" from local excitation sequences.
