Lyman break galaxies and the star formation rate of the Universe at z≈ 6
Lyman break galaxies and the star formation rate of the Universe at z≈ 6
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莱曼打破了星系和 z≈ 6 时宇宙的恒星形成率
DOI：
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发表时间：
2003
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通讯作者：
R. McMahon
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作者：
E. Stanway;A. Bunker;R. McMahon
利用Chandra深场南的深HST ACS SDSS-i′（F775 W）和SDSS-z′（F850 LP）以及VLT ISAAC J和Ks波段成像，测定了z = 1.6的紫外发光星暴星系的空间密度。我们发现8个星系和1颗星星的（i′−z′）> 1.5到z′AB= 25.6的深度（在3个可用的ACS历元中的每一个中都有8σ探测）。这对应于在z= 5.9时，未被遮蔽的星星形成速率为150 h−270 M <$yr−1，相当于在z= 3-4时莱曼破裂星族的L*（ΩΛ= 0.7，ΩM= 0.3）。我们对5.6 μ z <$7.0的恒星形成星系很敏感，在考虑了由于光度偏差而导致的高红移的不完整性后，有效共动体积为<$1.8 × 105 h −370 Mpc 3。这一卷应该包含了当前时代大约1000个L* 星系的祖先的原始亚银河尺度碎片。我们从亮度函数亮端的静止帧紫外选择性恒星爆发中确定了一个体积平均的全球星星形成速率为（6.7 ± 2.7）× 10− 4 h 70 M yr−1 Mpc−3，z = 6：这是一个下限，因为尘埃遮蔽和星系低于我们的敏感极限。这个测量结果表明，在z = 6时，明亮端的星星形成密度比Steidel等人在z= 3-4时对紫外选择星系的可比样本所测得的密度小10.6倍，因此将我们对宇宙星星形成历史的认识扩展到比以前的工作更早的时间，并进入可能发生再电离的时代。
We determine the space density of UV-luminous starburst galaxies at z≈ 6 using deep HST ACS SDSS-i′ (F775W) and SDSS-z′ (F850LP) and VLT ISAAC J and Ks band imaging of the Chandra Deep Field South. We find eight galaxies and one star with (i′−z′) > 1.5 to a depth of z′AB= 25.6 (an 8σ detection in each of the 3 available ACS epochs). This corresponds to an unobscured star formation rate of ≈15 h−270 M⊙ yr−1 at z= 5.9, equivalent to L* for the Lyman-break population at z= 3–4 (ΩΛ= 0.7, ΩM= 0.3). We are sensitive to star-forming galaxies at 5.6 ≲z≲ 7.0 with an effective comoving volume of ≈1.8 × 105h−370 Mpc3 after accounting for incompleteness at the higher redshifts due to luminosity bias. This volume should encompass the primeval subgalactic-scale fragments of the progenitors of about a thousand L* galaxies at the current epoch. We determine a volume-averaged global star formation rate of (6.7 ± 2.7) × 10−4h70 M⊙ yr−1 Mpc−3 at z∼ 6 from rest-frame UV selected starbursts at the bright end of the luminosity function: this is a lower limit because of dust obscuration and galaxies below our sensitivity limit. This measurement shows that at z∼ 6 the star formation density at the bright end is a factor of ∼6 times less than that determined by Steidel et al. for a comparable sample of UV-selected galaxies at z= 3–4, and so extends our knowledge of the star formation history of the Universe to earlier times than previous work and into the epoch where reionization may have occurred.