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arXiv 1808.09283astro-ph.GA
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利用图像叠加技术研究类星体吸收体宿主星系的性质

Studying Quasar Absorber Host Galaxy Properties Using Image Stacking Technique

Bill Zhu, Yinan Zhao, Jian Ge, Jingzhe Ma

备注：
19 pages, 14 figures, accepted by MNRAS. arXiv admin note: text overlap with arXiv:astro-ph/0609760 by other authors
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摘要：

研究类星体吸收体宿主星系的恒星质量、年龄、光度、恒星形成速率和碰撞参量，有助于理解星系形成和演化，并检验它们的模型。本文导出了低红移（$z_{abs} = 0.37 - 0.55$）Mg Ⅱ吸收体和高红移（$z_{abs} = 1.0 - 2.5$）2175尘埃吸收体（2DA）的光谱能量分布（SED）和碰撞参量极限。我们使用的成像叠加技术，统计提高的信噪比（SNR），以增加检测的吸收宿主星系。用主成分分析法（PCA）对背景类星体的点扩散函数进行了建模。该方法有效地降低了传统点扩散函数建模的不确定性。我们的SED镁II吸收体表明，低红移镁II吸收体宿主星系可能是恒星形成星系过渡到红色静止星系，低恒星形成率为2.2 $M_\odot$ $yr^{-1}$。从叠加的图像和模拟中，我们发现2DA的平均碰撞参量比Mg II吸收体的平均小5倍以上，小于7 kpc，而不是Mg II吸收体的48 kpc，这表明2DA可能与高红移星系的盘成分有关。这意味着2DA可能是研究银河系前身的良好探针。

英文摘要：

Studying the stellar mass, age, luminosity, star-formation rate, and impact parameter of quasar absorber host galaxies can aid in the understanding of galaxy formation and evolution as well as in testing their models. We derive the Spectral Energy Distribution (SED) and impact parameter limits of low redshift ($z_{abs} = 0.37 - 0.55$) Mg II absorbers and of higher redshift ($z_{abs} = 1.0 - 2.5$) 2175 Å dust absorbers (2DAs). We use an imaging stacking technique to statistically boost the signal-to-noise ratio (SNR) to increase detection of the absorber host galaxies. The point spread function of the background quasar is modeled with Principal Component Analysis (PCA). This method efficiently reduces the uncertainty of traditional PSF modeling. Our SED for Mg II absorbers indicates that low redshift Mg II absorber host galaxies are likely star-forming galaxies transitioning into red quiescent galaxies, with a low star formation rate of 2.2 $M_\odot$ $yr^{-1}$. From the stacked images and simulations, we show that the average impact parameter of 2DAs is > 5 times smaller than that of Mg II absorbers, at < 7 kpc instead of Mg II absorbers' 48 kpc, indicating that 2DAs are likely associated with disk components of high redshift galaxies. This means that 2DAs are likely good probes to study precursors to the Milky Way.

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