THE GREAT OBSERVATORIES ORIGINS DEEP SURVEY: CONSTRAINTS ON THE LYMAN CONTINUUM ESCAPE FRACTION DISTRIBUTION OF LYMAN-BREAK GALAXIES AT 3.4 < z < 4.5
THE GREAT OBSERVATORIES ORIGINS DEEP SURVEY: CONSTRAINTS ON THE LYMAN CONTINUUM ESCAPE FRACTION DISTRIBUTION OF LYMAN-BREAK GALAXIES AT 3.4 < z < 4.5
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DOI：
10.1088/0004-637x/725/1/1011
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发表时间：
2010-09
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通讯作者：
E. Vanzella;M. Giavalisco;A. Inoue;M. Nonino;F. Fontanot;S. Cristiani;A. Grazian;M. Dickinson;D. Stern;P. Tozzi;E. Giallongo;H. Ferguson;H. Spinrad;K. Boutsia;A. Fontana;P. Rosati;L. Pentericci
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作者：
E. Vanzella;M. Giavalisco;A. Inoue;M. Nonino;F. Fontanot;S. Cristiani;A. Grazian;M. Dickinson;D. Stern;P. Tozzi;E. Giallongo;H. Ferguson;H. Spinrad;K. Boutsia;A. Fontana;P. Rosati;L. Pentericci
我们使用超深紫外VLT/VIMOS中间波段和VLT/FORS 1窄带成像在GOODS南场导出的L L*z=3莱曼break星系（LBG）在红移3.4-4.5的电离辐射逃逸分数（fesc）的分布的限制。只有一个红移z = 3.795的LBG在它的莱曼连续谱（LyC; S/N = 5.5）中被探测到，这是目前已知的直接探测到的最高红移星系。它的紫外线形态是相当紧凑的（参考= 0.8千秒差距物理）。七个活动星系核中有三个也在它们的LyC中被探测到，其中包括一个红移z = 3.951和z 850 = 26.1。根据堆叠数据（LBG），我们将平均fesc的上限设置在5%-20%的范围内，这取决于如何选择数据（例如，通过幅度和/或红移）。我们进行了广泛的蒙特卡罗模拟，考虑到星系际衰减，恒星人口合成模型，尘埃消光和光度噪声，以探索逃逸辐射分布的时刻。各种分布（指数，对数正态和高斯）进行了探索。我们发现fesc的中位数低于106%，84%的百分位数限制不大于20%。如果这一结果仍然适用于较暗的LBG下降到目前的观测极限，那么LBG人口可能不足以占整个光电离预算在这里考虑的红移，与确切的细节取决于假设的电离背景和类星体的贡献。fesc可能取决于星系的紫外光度，较暗的星系有较高的fesc，从HUDF（i775 <$28.5）的微弱LBG样本中估计的fesc与这种情况有广泛的定量一致性。
We use ultra-deep ultraviolet VLT/VIMOS intermediate-band and VLT/FORS1 narrowband imaging in the GOODS Southern field to derive limits on the distribution of the escape fraction (fesc) of ionizing radiation for L ⩾ L*z=3 Lyman-break galaxies (LBGs) at redshift 3.4–4.5. Only one LBG, at redshift z = 3.795, is detected in its Lyman continuum (LyC; S/N ≃ 5.5), the highest redshift galaxy currently known with a direct detection. Its ultraviolet morphology is quite compact (Reff = 0.8 kpc physical). Three out of seven active galactic nuclei are also detected in their LyC, including one at redshift z = 3.951 and z850 = 26.1. From stacked data (LBGs), we set an upper limit to the average fesc in the range 5%–20%, depending on how the data are selected (e.g., by magnitude and/or redshift). We undertake extensive Monte Carlo simulations that take into account intergalactic attenuation, stellar population synthesis models, dust extinction, and photometric noise in order to explore the moments of the distribution of the escaping radiation. Various distributions (exponential, log-normal, and Gaussian) are explored. We find that the median fesc is lower than ≃6% with an 84% percentile limit not larger than 20%. If this result remains valid for fainter LBGs down to current observational limits, then the LBG population might be not sufficient to account for the entire photoionization budget at the redshifts considered here, with the exact details dependent upon the assumed ionizing background and QSO contribution thereto. It is possible that fesc depends on the UV luminosity of the galaxies, with fainter galaxies having higher fesc, and estimates of fesc from a sample of faint LBGs from HUDF (i775 ⩽28.5) are in broad quantitative agreement with such a scenario.