STRONG FIELD-TO-FIELD VARIATION OF Lyα NEBULAE POPULATIONS AT z ≃ 2.3
STRONG FIELD-TO-FIELD VARIATION OF Lyα NEBULAE POPULATIONS AT z ≃ 2.3
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DOI：
10.1088/0004-637x/719/2/1654
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发表时间：
2010-08
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影响因子：
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通讯作者：
Yujin Yang;A. Zabludoff;D. Eisenstein;R. Davè
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作者：
Yujin Yang;A. Zabludoff;D. Eisenstein;R. Davè
了解遥远的Lyα星云的本质，也就是“斑点”，并将它们与今天的后代联系起来，需要限制它们的数量密度、聚集性和大规模环境。为了测量这些基本量，我们在四个不同的区域，钱德拉深场南(CDFS)，钱德拉深场北(CDFN)和两个COSMOS子场进行了深部窄带成像调查，总调查面积为1.2°2。我们在z=2.3时发现了25个团簇，其Lyα亮度为llyα=(0.7-8)×1043erg S−1，等光区面积为10-60。从紧凑型Lyα发射体(LAE；少数Liso∼)到扩展Lyα斑点(AISO>；10)的转变是连续的，这表明一个家族可能受到类似的发射机制的支配。令人惊讶的是，大多数斑点(16/25)都在一个调查领域，即CDF。6个最亮、最大的斑点，α≳1.5×1043erg S−1和AISO>；16只位于CDF中。这些大而明亮的斑点关于其数密度n∼1.0+1.8−0.6×10−5 MPC−3的场到场的方差为σv∼1.5(150%)。这个方差很大，显著高于未分辨的LAE(LAE v LAE 0.3或30%)，并且可能对不同测量之间的斑点数密度和光度函数(LF)的比较产生不利影响。我们深入、盲目的调查使我们能够构建一个可靠的斑点LF。在1h的−1GPC宇宙N体模拟中，我们比较了我们的斑点和暗物质晕的统计。在z=2.3时，n意味着如果大多数晕具有可检测到的斑点，则每个明亮、大的斑点可以占据MHALO≳1013M☉的晕。N的预测变化与观测一致，并与∼7的偏差相对应。斑点晕位于z=2.3时晕质量分布的高端，很可能演化为当今星系团典型的∼1014M☉晕。在较大尺度的∼10移动的MPC上，斑点聚集在致密的LAE聚集的地方，表明斑点位于相干的、高度过密集的结构中。
Understanding the nature of distant Lyα nebulae, aka “blobs,” and connecting them to their present-day descendants requires constraining their number density, clustering, and large-scale environment. To measure these basic quantities, we conduct a deep narrowband imaging survey in four different fields, Chandra Deep Field South (CDFS), Chandra Deep Field North (CDFN), and two COSMOS subfields, for a total survey area of 1.2 deg2. We discover 25 blobs at z = 2.3 with Lyα luminosities of LLyα= (0.7–8) × 1043 erg s−1 and isophotal areas of Aiso = 10–60 . The transition from compact Lyα emitters (LAEs; Aiso ∼ a few ) to extended Lyα blobs (Aiso > 10 ) is continuous, suggesting a single family perhaps governed by similar emission mechanisms. Surprisingly, most blobs (16/25) are in one survey field, the CDFS. The six brightest, largest blobs with LLyα ≳ 1.5×1043 erg s−1 and Aiso > 16 lie only in the CDFS. These large, bright blobs have a field-to-field variance of σv ≳ 1.5 (150%) about their number density n ∼1.0+1.8−0.6× 10−5 Mpc−3. This variance is large, significantly higher than that of unresolved LAEs (σv ∼ 0.3 or 30%), and can adversely affect comparisons of blob number densities and luminosity functions (LFs) among different surveys. Our deep, blind survey allows us to construct a reliable blob LF. We compare the statistics of our blobs with dark matter halos in a 1 h−1 Gpc cosmological N-body simulation. At z = 2.3, n implies that each bright, large blob could occupy a halo of Mhalo ≳1013 M☉ if most halos have detectable blobs. The predicted variance in n is consistent with that observed and corresponds to a bias of ∼7. Blob halos lie at the high end of the halo mass distribution at z = 2.3 and are likely to evolve into the ∼1014 M☉ halos typical of galaxy clusters today. On larger scales of ∼10 comoving Mpc, blobs cluster where compact LAEs cluster, indicating that blobs lie in coherent, highly overdense structures.