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arXiv 1807.07080astro-ph.GA
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透镜星暴的远红外赫歇尔SPIRE光谱揭示了电离气体的物理条件

Far-infrared Herschel SPIRE spectroscopy of lensed starbursts reveals physical conditions of ionised gas

Zhi-Yu Zhang, R. J. Ivison, R. D. George, Yinghe Zhao, L. Dunne, R. Herrera-Camus, A. J. R. Lewis, Daizhong Liu, D. Naylor, Ivan Oteo, D. A. Riechers, Ian Smail… 展开作者

Zhi-Yu Zhang, R. J. Ivison, R. D. George, Yinghe Zhao, L. Dunne, R. Herrera-Camus, A. J. R. Lewis, Daizhong Liu, D. Naylor, Ivan Oteo, D. A. Riechers, Ian Smail, Chentao Yang, Stephen Eales, Ros Hopwood, Steve Maddox, Alain Omont, Paul van der Werf

摘要:

最密集的恒星形成星系在远红外(FIR)波长处非常明亮,在光学和紫外波长处非常模糊,位于$z\ge 1-3$。我们提出了一个计划的${\it Herschel}$ FIR光谱观测与SPIRE FTS和光度观测与PACS,无论是在船上${\it Herschel}$,对一个样本的45引力透镜,尘埃星暴横跨$z\sim 1-3.6$。总共,我们检测到27条低至3- $σ$的单独谱线,包括9条具有确认的光谱红移的$[\rm C{\small II}]$ 158- $μ$ m谱线,5条与它们的远红外光度红移一致的可能的$[\rm C{\small II}]$谱线,以及在一些单独的源中的一些$[\rm O{\small III}]$ 88- $μ$ m、$[\rm O{\small III}]$ 52- $μ$ m、$[\rm O{\small I}]$ 145- $μ$ m、$[\rm O{\small I}]$ 63- $μ$ m、MT $[\rm N{\small II}]$ 122- $μ$ m和OH 119- $μ$ m(吸收)谱线。为了获得样品中气体的典型物理性质,我们将所有光谱按其固有光度和500- $μ$ m通量密度进行加权,并将光谱缩放到一个共同的红移。在堆叠光谱中,我们以高保真度检测$[\rm C{\small II}]$ 158- $μ$ m、$[\rm N{\small II}]$ 122- $μ$ m、$[\rm O{\small III}]$ 88- $μ$ m、$[\rm O{\small III}]$ 52- $μ$ m、$[\rm O{\small I}]$ 63- $μ$ m的发射线以及在119- $μ$ m处的OH的吸收双峰。我们发现,在相同的示踪剂下,$[\rm N{\small II}]$和$[\rm O{\small III}]$谱线追踪到的平均电子密度高于本地恒星形成星系和ULIRGs的平均值。从$[\rm N{\small II}]/[\rm C{\small II}]$和$[\rm O{\small I}]/[\rm C{\small II}]$的比率,我们发现,$[\rm C{\small II}]$的排放可能是由光主导区(PDR),而不是由电离气体或大规模的冲击。

英文摘要:

The most intensively star-forming galaxies are extremely luminous at far-infrared (FIR) wavelengths, highly obscured at optical and ultraviolet wavelengths, and lie at $z\ge 1-3$. We present a programme of ${\it Herschel}$ FIR spectroscopic observations with the SPIRE FTS and photometric observations with PACS, both on board ${\it Herschel}$, towards a sample of 45 gravitationally lensed, dusty starbursts across $z\sim 1-3.6$. In total, we detected 27 individual lines down to 3-$σ$, including nine $[\rm C{\small II}]$ 158-$μ$m lines with confirmed spectroscopic redshifts, five possible $[\rm C{\small II}]$ lines consistent with their far-infrared photometric redshifts, and in some individual sources a few $[\rm O{\small III}]$ 88-$μ$m, $[\rm O{\small III}]$ 52-$μ$m, $[\rm O{\small I}]$ 145-$μ$m, $[\rm O{\small I}]$ 63-$μ$m, $[\rm N{\small II}]$ 122-$μ$m, and OH 119-$μ$m (in absorption) lines. To derive the typical physical properties of the gas in the sample, we stack all spectra weighted by their intrinsic luminosity and by their 500-$μ$m flux densities, with the spectra scaled to a common redshift. In the stacked spectra, we detect emission lines of $[\rm C{\small II}]$ 158-$μ$m, $[\rm N{\small II}]$ 122-$μ$m, $[\rm O{\small III}]$ 88-$μ$m, $[\rm O{\small III}]$ 52-$μ$m, $[\rm O{\small I}]$ 63-$μ$m, and the absorption doublet of OH at 119-$μ$m, at high fidelity. We find that the average electron densities traced by the $[\rm N{\small II}]$ and $[\rm O{\small III}]$ lines are higher than the average values in local star-forming galaxies and ULIRGs, using the same tracers. From the $[\rm N{\small II}]/[\rm C{\small II}]$ and $[\rm O{\small I}]/[\rm C{\small II}]$ ratios, we find that the $[\rm C{\small II}]$ emission is likely dominated by the photo-dominated regions (PDR), instead of by ionised gas or large-scale shocks.

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