The GALEX Arecibo SDSS survey – III. Evidence for the inside‐out formation of Galactic discs
The GALEX Arecibo SDSS survey – III. Evidence for the inside‐out formation of Galactic discs
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DOI：
10.1111/j.1365-2966.2010.17962.x
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发表时间：
2010-11
影响因子：
4.8
通讯作者：
Jing Wang;G. Kauffmann;R. Overzier;B. Catinella;D. Schminovich;T. Heckman;S. Moran;M. Haynes
中科院分区：
文献类型：
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作者：
Jing Wang;G. Kauffmann;R. Overzier;B. Catinella;D. Schminovich;T. Heckman;S. Moran;M. Haynes
我们分析了恒星质量大于1010 M圆点且红移范围为0.025 < z < 0.05的星系样本，其中H i质量测量可从GALEX Arecibo SDSS（斯隆数字巡天）巡天（GASS）或Arecibo Legacy快速ALFA巡天（ALFALFA）中获得。在一个给定的M-* 值，我们的样本主要由比平均水平更富氢的星系组成。我们构造了一系列的三个控制样本与这些富H i星系进行比较：一个样本在恒星质量和红移（C-M*）上匹配，第二个样本在恒星质量、NUV-r颜色和红移（C-M*，C-NUV- r）上匹配，第三个样本在恒星质量、NUV-r颜色、恒星表面质量密度μ（*）和红移上匹配。我们产生了自洽的七波段测光（FUV，NUV，u，g，r，i，z）的所有星系，我们用它来获得内部的颜色，外部的颜色，不对称性和平滑度参数。我们还使用标准的光谱能量分布（SED）拟合技术，以获得内部和外部特定的星星形成率（sSFR）。正如预期的那样，H i丰富的星系强烈不同的星系相同的恒星质量，选择不考虑H i内容。这些差异的大部分是由于这样一个事实，即有更多气体的星系更蓝，更活跃的星星形成。为了识别与H i含量有因果关系的星系属性，我们将H i样本得出的结果与恒星质量、大小和NUV-r颜色匹配的星系得出的结果进行了比较。唯一的光度属性，这是明确归因于增加H i含量是颜色梯度的星系。与星系内部相比，具有较大H i分数的星系具有更蓝，更活跃的恒星形成外盘。富氢星系的g带半径也比i带半径大。我们的研究结果是一致的盘星系形成的“由内而外”的图片，这通常作为半解析模型的基础上形成的光盘在冷暗物质宇宙学的背景下。H i分数和星系不对称性之间缺乏任何内在联系，表明气体是平稳地吸积到外盘上的。
We analyse a sample of galaxies with stellar masses greater than 1010 M-circle dot and with redshifts in the range 0.025 < z < 0.05 for which H i mass measurements are available from the GALEX Arecibo SDSS (Sloan Digital Sky Survey) Survey (GASS) or from the Arecibo Legacy Fast ALFA survey (ALFALFA). At a given value of M-*, our sample consists primarily of galaxies that are more H i-rich than average. We constructed a series of three control samples for comparison with these H i-rich galaxies: one sample is matched in stellar mass and redshift (C-M*), the second sample is matched in stellar mass, NUV - r colour and redshift (C-M*,C- NUV - r), and the third sample is matched in stellar mass, NUV - r colour, stellar surface mass density mu(*) and redshift. We generated self-consistent seven-band photometry (FUV, NUV, u, g, r, i, z) for all galaxies, and we used this to derive inner colours, outer colours, asymmetry and smoothness parameters. We also used standard spectral energy distribution (SED) fitting techniques to derive inner and outer specific star formation rates (sSFR). As expected, H i-rich galaxies differ strongly from galaxies of the same stellar mass that are selected without regard to H i content. The majority of these differences are attributable to the fact that galaxies with more gas are bluer and more actively star forming. In order to identify those galaxy properties that are causally connected with H i content, we compare results derived for the H i sample with those derived for galaxies matched in stellar mass, size and NUV - r colour. The only photometric property that is clearly attributable to increasing H i content is the colour gradient of the galaxy. Galaxies with larger H i fractions have bluer, more actively star-forming outer discs compared to the inner part of the galaxy. H i-rich galaxies also have larger g-band radii compared to i-band radii. Our results are consistent with the 'inside-out' picture of disc galaxy formation, which has commonly served as a basis for semi-analytic models of the formation of discs in the context of cold dark matter cosmologies. The lack of any intrinsic connection between H i fraction and galaxy asymmetry suggests that gas is accreted smoothly on to the outer disc.