Star Formation at z~6: i-dropouts in the ACS GTO fields
Star Formation at z~6: i-dropouts in the ACS GTO fields
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z~6 处的恒星形成：ACS GTO 场中的 i-dropouts
DOI：
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发表时间：
2003
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通讯作者：
R. Zheng
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作者：
R. Bouwens;G. Illingworth;P. Rosati;C. Lidman;T. Broadhurst;M. Franx;H. Ford;D. Magee;N. Benı́tez;J. Blakeslee;G. Meurer;M. Clampin;G. Hartig;D. Ardila;F. Bartko;R. Brown;C. Burrows;E. Cheng;N. Cross;P. Feldman;D. Golimowski;C. Gronwall;L. Infante;R. Kimble;J. Krist;M. Lesser;A. Martel;F. Menanteau;G. Miley;M. Postman;M. Sirianni;W. Sparks;H. Tran;Z. Tsvetanov;R. Zheng
利用i-z丢失判据，利用深光学-红外成像，从两个深ACS GTO场测量了z~6星系的空间密度。在46弧分^[2]范围内总共发现了23个天体，也就是说，在z~ 27. 3（6 σ;都是AB等）范围内，每弧分^[2]大约有0. 5个天体（包括一个可能的z~6活动星系核）。结合我们的RDCS 1252 -2927场的深层ISAAC数据（J~25.7和Ks~25.0（5 sigma））和HDF North的NICMOS数据（JH~27.3（5 sigma）），我们验证了这些脱落具有平坦的光谱斜率。在我们的样本中，i-脱落的亮度范围从~1.5 L*（z~25.6）到~0.3 L*（z~27.3），除了一个非常明亮的候选者在z~24.2处。半光半径从0.09”到0.29”不等，或从0.5 kpc到1.7 kpc不等。我们使用三种不同的程序推导出z~6静止帧UV光度密度，每种程序都利用基于CDF South V dropout样本的模拟。首先，我们将我们的研究结果与这个V-辍学样本的非进化预测进行比较。我们发现23+/-25%以上的i-辍学比我们预测的。采用以前的结果到z~5，这计算出从z~3到z~6的光度密度下降了20+/-29%。其次，我们使用这些相同的V-dropout模拟来导出我们的i-dropout样本的选择函数，并计算UV光度密度（7.2+/-2.5 x 10^25 ergs/s/Hz/Mpc ^3，直到z~27）。我们发现在相同的红移范围内下降了39+/-21%。这是我们的首选值，表明星星的形成速率为0.0090+/-0.0031 M_sol/yr/Mpc ^3到z~27，或者将LF外推到微弱极限时为~0.036+/-0.012 M_sol/yr/Mpc ^3。第三，我们遵循一个非常相似的过程，但假设没有不完整性，发现一个光度密度低2- 3倍。这一最后估计数是一个下限。所有这三个估计都在这个时期宇宙再电离所需的典型光度密度范围内。（节略）
Using an i-z dropout criterion, we determine the space density of z~6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin^2, or ~0.5 objects/arcmin^2 down to z~27.3 (6 sigma; all AB mag) (including one probable z~6 AGN). Combining deep ISAAC data for our RDCS1252-2927 field (J~25.7 and Ks~25.0 (5 sigma)) and NICMOS data for the HDF North (JH~27.3 (5 sigma)), we verify that these dropouts have flat spectral slopes. i-dropouts in our sample range in luminosity from ~1.5 L* (z~25.6) to ~0.3 L* (z~27.3) with the exception of one very bright candidate at z~24.2. The half-light radii vary from 0.09" to 0.29", or 0.5 kpc to 1.7 kpc. We derive the z~6 rest-frame UV luminosity density using three different procedures, each utilizing simulations based on a CDF South V dropout sample. First, we compare our findings with a no-evolution projection of this V-dropout sample. We find 23+/-25% more i-dropouts than we predict. Adopting previous results to z~5, this works out to a 20+/-29% drop in the luminosity density from z~3 to z~6. Second, we use these same V-dropout simulations to derive a selection function for our i-dropout sample and compute the UV-luminosity density (7.2+/-2.5 x 10^25 ergs/s/Hz/Mpc^3 down to z~27). We find a 39+/-21% drop over the same redshift range. This is our preferred value and suggests a star formation rate of 0.0090+/-0.0031 M_sol/yr/Mpc^3 to z~27, or ~0.036+/- 0.012 M_sol/yr/Mpc^3 extrapolating the LF to the faint limit. Third, we follow a very similar procedure, but assume no incompleteness, finding a luminosity density which is ~2-3X lower. This final estimate constitutes a lower limit. All three estimates are within the canonical range of luminosity densities necessary for reionization of the universe at this epoch. (abridged)