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arXiv 1907.09680astro-ph.GAastro-ph.CO
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未来星系红移巡天中H $α$和[ OIII ]发射线星系数的预测

Prediction of H$α$ and [OIII] Emission Line Galaxy Number Counts for Future Galaxy Redshift Surveys

Zhongxu Zhai, Andrew Benson, Yun Wang, Gustavo Yepes, Chia-Hsun Chuang

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12 pages, 7+2 figures, 2 table; updated to match version accepted by MNRAS
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摘要：

我们进行了模拟与Galacticus，半解析星系形成模型，预测的H $α$和[OIII]发射星系的数量计数。利用最先进的N体模拟UNIT，我们首先用当前观测到的H $α$光度函数校准Galacticus。与尘埃衰减模型相结合，得到的模型可以重现当前的观测，包括H $α$光度函数从HiZELS和数密度从WISP。我们将模型预测外推到更高的红移，发现结果与以前的调查是一致的。然后，我们使用相同的星系形成模型来预测[OIII]发射星系的数量。这一结果进一步验证了我们的星系形成模型和尘埃模型。我们提出了H $α$和[OIII]发射线星系在三种不同的线通量极限下的数量计数：$5\times10^{-17}$ erg/s/cm $^{2}$，$1\times10^{-16}$ erg/s/cm $^{2}$（WFIRST GRS的6.5 $σ$标称深度）和$2\times10^{-16}$ erg/s/cm $^{2}$（欧几里得GRS的3.5 $σ$深度）。在红移$2<z<3$，我们的模型预测，WFIRST可以观察到数百个[OIII]发射线星系每平方度的线通量极限为$1\times10^{-16}$ erg/s/cm $^{2}$。这将提供大尺度结构的精确测量，以探测巨大宇宙体积上的暗能量，达到前所未有的高红移。最后，我们比较了在$0<z<3$的红移范围内H $α$ /[OIII]的通量比。我们的结果表明，已知的趋势，增加H $α$ /[O III]流量比与H $α$流量在低红移，这成为一个较弱的趋势，在较高的红移。

英文摘要：

We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H$α$ and [OIII] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H$α$ luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H$α$ luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [OIII] emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H$α$ and [OIII] emission line galaxies for three different line flux limits: $5\times10^{-17}$erg/s/cm$^{2}$, $1\times10^{-16}$erg/s/cm$^{2}$ (6.5$σ$ nominal depth for WFIRST GRS), and $2\times10^{-16}$erg/s/cm$^{2}$ (3.5$σ$ depth of Euclid GRS). At redshift $2<z<3$, our model predicts that WFIRST can observe hundreds of [OIII] emission line galaxies per square degree with a line flux limit of $1\times10^{-16}$erg/s/cm$^{2}$. This will provide accurate measurement of large scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H$α$/[OIII] within the redshift range of $0<z<3$. Our results show the known trend of increasing H$α$/[O III] flux ratio with H$α$ flux at low redshift, which becomes a weaker trend at higher redshifts.

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