THE UDF05 FOLLOW-UP OF THE HUBBLE ULTRA DEEP FIELD. II. CONSTRAINTS ON REIONIZATION FROM Z-DROPOUT GALAXIES
THE UDF05 FOLLOW-UP OF THE HUBBLE ULTRA DEEP FIELD. II. CONSTRAINTS ON REIONIZATION FROM Z-DROPOUT GALAXIES
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哈勃超深场的 UDF05 后续行动。
DOI：
10.1088/0004-637x/690/2/1350
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
N. Panagia
中科院分区：
文献类型：
--
作者：
P. Oesch;C. Carollo;M. Stiavelli;M. Trenti;L. Bergeron;A. Koekemoer;R. Lucas;C. Pavlovsky;S. Beckwith;T. Dahlén;H. Ferguson;J. Gardner;S. Lilly;B. Mobasher;N. Panagia;N. Panagia
我们在我们的UDF 05哈勃太空望远镜近红外相机和多目标光谱仪图像的两个单独的领域（哈勃超深场和NICP 34）中检测到三个（加上一个不太确定的）z 850-dropout源。这些z ≥ 7的莱曼破裂星系（LBG）候选者使我们能够限制这些时期恒星形成星系群的光度函数（LF）。假设只有M* 的变化，并采用红移的线性演化，锚定在z = 6的测量值上，发现最佳拟合的演化系数为每单位红移0.43 ± 0.19等（如果包括所有四个候选者，则为0.36 ± 0.18），这提供了M*（z = 7.2）= −19.7 ± 0.3。这意味着LBG的光度密度在z 1.6和z 1.7之间的1.7亿年内下降了1.2 -2.5倍，并且LBG LF以与整个z 1.3 -6周期相同的速率稳定地演化到z 1.7。这对z 6个星系的恒星形成历史施加了强有力的约束，在它们被观察到的时代之前，其系综恒星形成率（SFR）密度必须在2170 Myr时低2倍。特别是，在z <$6 LBG星族中，有很大一部分恒星的红移必须远高于z <$7。LBG群体产生的电离光子的速率随着宇宙SFR密度的降低而一致地降低。将这种稳定的低频演化外推到更高的红移，我们估计星系将能够使宇宙的电离光子增加z <$6，前提是z > 7的低频的暗端斜率变陡到α <$−1.9，并且亮度低于当前探测极限的暗星系贡献了所需电离光子的很大一部分。然而，这种情况下，电子散射的积分光学深度比威尔金森微波各向异性探针-5测量值低102 σ。因此，总的来说，我们的研究结果表明，如果星系是主要的贡献者再电离，无论是目前检测到的星系人口的演变减慢在z 107，或LF的演变必须通过减少金属丰度和相应的增加电离效率在这些早期时期的补偿。
We detect three (plus one less certain) z850-dropout sources in two separate fields (Hubble Ultra Deep Field and NICP34) of our UDF05 Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer images. These z ∼ 7 Lyman-break Galaxy (LBG) candidates allow us to constrain the Luminosity Function (LF) of the star-forming galaxy population at those epochs. By assuming a change in only M* and adopting a linear evolution in redshift, anchored to the measured values at z ∼ 6, the best-fit evolution coefficient is found to be 0.43 ± 0.19 mag per unit redshift (0.36 ± 0.18, if including all four candidates), which provides a value of M*(z = 7.2) = −19.7 ± 0.3. This implies a drop in the luminosity density in LBGs by a factor of ∼2–2.5 over the ∼ 170 Myr that separate z ∼ 6 and z ∼ 7, and a steady evolution for the LBG LF out to z ∼ 7, at the same rate that is observed throughout the z ∼ 3–6 period. This puts a strong constraint on the star-formation histories of z ∼ 6 galaxies, whose ensemble star-formation rate (SFR) density must be lower by a factor of 2 at ∼ 170 Myr before the epoch at which they are observed. In particular, a large fraction of stars in the z ∼ 6 LBG population must form at redshifts well above z ∼ 7. The rate of ionizing photons produced by the LBG population consistently decreases with the decrease in the cosmic SFR density. Extrapolating this steady evolution of the LF out to higher redshifts, we estimate that galaxies would be able to reionize the universe by z ∼ 6, provided that the faint-end slope of the z > 7 LF steepens to α ∼ −1.9 and that faint galaxies with luminosities below the current detection limits contribute a substantial fraction of the required ionizing photons. This scenario, however, gives an integrated optical depth to electron scattering that is ∼2σ below the Wilkinson Microwave Anisotropy Probe-5 measurement. Therefore, altogether, our results indicate that, should galaxies be the primary contributors to reionization, either the currently detected evolution of the galaxy population slows down at z ≳ 7, or the LF evolution must be compensated by a decrease in metallicity and a corresponding increase in ionization efficiency at these early epochs.
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影响因子：
64.8
作者：
Iye, Masanori;Ota, Kazuaki;Shimasaku, Kazuhiro
通讯作者：
Shimasaku, Kazuhiro
DOI：
10.1111/j.1365-2966.2007.11455.x
发表时间：
2007-01
影响因子：
4.8
作者：
A. Verma;M. Lehnert;N. F. Schreiber;M. Bremer;Laura Douglas Mpe;Garching;H Germany;U. Oxford;U.K.;U. Bristol
通讯作者：
A. Verma;M. Lehnert;N. F. Schreiber;M. Bremer;Laura Douglas Mpe;Garching;H Germany;U. Oxford;U.K.;U. Bristol
斯巴鲁深场中 z=4 和 5 处莱曼断裂星系的聚类：光度依赖性
DOI：
--
发表时间：
2006
期刊：
Ap.J. 637
影响因子：
--
作者：
Kashikawa;N.;Yahagi;M.;Shimasaku;K.;Nagashima;M.他
通讯作者：
M.他
z=7 Lyα 发射器探测再电离和星系演化
DOI：
--
发表时间：
2008
期刊：
ApJ 677
影响因子：
--
作者：
Ota;K;Iye;M;Kashikawa;N.;他
通讯作者：
他