Interpreting high [O iii]/H β ratios with maturing starbursts
Interpreting high [O iii]/H β ratios with maturing starbursts
复制标题
解释成熟星暴的高 [O iii]/H β 比率
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Bremer
中科院分区：
文献类型：
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作者：
E. Stanway;J. Eldridge;S. Greis;L. Davies;S. Wilkins;M. Bremer
通过光学发射线的比率来测量，处于高红移的恒星形成星系普遍表现出高电离参数。我们证明，选择作为莱曼断裂类似物的本地（z < 0.2）源也表现出高线比，典型的[O III]/Hβ=3.36+0.14−0.04——与在z ∼ 2-4处的恒星形成星系中看到的最高比值相当。我们认为，恒星族合成代码 BPASS 可以解释快速形成的恒星族老化所需的高电离参数，而不需要任何活动星系核的贡献。相对于单恒星演化代码预测的那些，双星恒星演化路径延长了星暴可能显示出更高的线比的年龄间隔。因此，星暴后金属丰度接近太阳且年龄高达∼100 Myr的模型星系通常具有线比[O III]/Hβ∼3，与莱曼断裂星系和具有相似恒星形成密度的本地来源中看到的一致。这强调了在模拟年轻或爆发恒星群的星云线发射时包括二元演化路径的重要性。
Star-forming galaxies at high redshift show ubiquitously high-ionization parameters, as measured by the ratio of optical emission lines. We demonstrate that local (z < 0.2) sources selected as Lyman break analogues also manifest high line ratios with a typical [O III]/Hβ=3.36+0.14−0.04 – comparable to all but the highest ratios seen in star-forming galaxies at z ∼ 2–4. We argue that the stellar population synthesis code BPASS can explain the high-ionization parameters required through the ageing of rapidly formed star populations, without invoking any AGN contribution. Binary stellar evolution pathways prolong the age interval over which a starburst is likely to show elevated line ratios, relative to those predicted by single stellar evolution codes. As a result, model galaxies at near-solar metallicities and with ages of up to ∼100 Myr after a starburst typically have a line ratio [O III]/Hβ ∼ 3, consistent with those seen in Lyman break galaxies and local sources with similar star formation densities. This emphasises the importance of including binary evolution pathways when simulating the nebular line emission of young or bursty stellar populations.