论文标题
碳碳质量SDSS的Boss QSO2在Z> 2：高密度气体还是碳的继发生产？
Carbon-loud SDSS BOSS QSO2s at z > 2: High density gas or secondary production of Carbon?
论文作者
论文摘要
我们研究了Sloan数字天空调查III BARYON振荡光谱调查的145型II型类星体（QSO2S）样品的紫外线（UV）发射线比，并与活性银河系核（AGN）光电离心模型的网格进行比较，并与气体密度，化学含量覆盖范围的范围，气体密度，化学覆盖量和离子化参数。大多数类星体都是“碳大风”，狭窄线区域的CIV/HE II比异常高，这意味着高于预期的气体密度（> 10^6 cm^-3）和/或超极性相对碳的丰度。我们还发现，在我们的大多数样品中，都需要太阳或超级氮的丰度和金属性，并且物体之间的潜在显着变化。与类似的红移（HZRGS; Z> 2）处的射电星系相比，QSO2s被抵消到更高的NV/HEII，CIV/HEII和CIII和HEII]/HEII，这表明系统上较高的气体密度和/或系统上更高的C和N丰度。我们没有发现两种类型对象之间N/C丰度比的系统差异的证据。 NIV/CIV比率的散射意味着QSO2S和HZRG之间的N/C丰度比存在显着散射，与物体之间的化学富集历史的差异一致。有趣的是，我们发现为N和C采用次要行为会减轻长期存在的“ NIV]问题”。 QSO2S和HZRG的子集似乎也是“硅云”，其相对通量表明Si/C和Si/O比其太阳值高出一个数量级。最后，我们提出了新的UV线标准，以选择具有低密度窄线区域的真正QSO2。
We study the ultraviolet (UV) emission-line ratios of a sample of 145 type II quasars (QSO2s) from Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey, and compare against a grid of active galactic nucleus (AGN) photoionization models with a range in gas density, gas chemical abundances, and ionization parameter. Most of the quasars are "carbon-loud", with Civ/He ii ratios that are unusually high for the narrow-line region, implying higher than expected gas density (>10^6 cm^-3) and/or signicantly super-Solar relative carbon abundance. We also find that solar or supersolar nitrogen abundance and metallicity are required in the majority of our sample, with potentially significant variation between objects. Compared to radio galaxies at similar redshifts (HzRGs; z > 2), the QSO2s are offset to higher NV/HeII, CIV/HeII and CIII]/HeII, suggesting systematically higher gas density and/or systematically higher C and N abundances. We find no evidence for a systematic difference in the N/C abundance ratio between the two types of objects. Scatter in the NIV]/CIV ratio implies a significant scatter in the N/C abundance ratio among the QSO2s and HzRGs, consistent with differences in the chemical enrichment histories between objects. Interestingly, we find that adopting secondary behaviour for both N and C alleviates the long-standing "NIV] problem". A subset of the QSO2s and HzRGs also appear to be "silicon-loud", with SiIII] relative fluxes suggesting Si/C and Si/O are an order of magnitude above their Solar values. Finally, we propose new UV-line criteria to select genuine QSO2s with low-density narrow-line regions.
