在z=2.23时对过密区域的H-alpha搜索
An H-alpha search for over-dense regions at z=2.23
摘要：
我们提出了一个窄带的结果，（H2 S1，2.121/0.021um）使用WFCAM/UKIRT成像搜索几个潜在的稀有标志周围的H-α发射体（10^-7-10^-8 Mpc^-3）z=2.23时的过密区域：类星体密度过大（2 QZ星团），一个强大的高红移射电星系（HzRG），以及亚毫米星系（SMG）和光学昏暗射电星系（OFRG）的集中。我们总共探测到137个窄带发射源候选者，其发射线通量为0.5-1 x 10^-16尔格·s^-1 cm^-2，总面积为0.56平方米。度（在z=2.23时，共动Mpc为2.1 x 10^5）。发射体的BzK颜色表明，我们的样品中至少有80%可能是z=2.23的H-α发射体（HAE）。这是在z>2处已知的最大HAE样品之一。我们发现适度的（~3-西格玛）与所有三个目标相关的发射器的局部过密度。在2 QZ星团场中，发射体呈现出一个显著的平行结构，它连接着4个z=2.23的类星体，延伸范围超过30 Mpc（共动）。在HzRG和SMG/OFRG场中，结构似乎较小，仅在目标附近可见。发射体的K-波段幅度和H-α等效宽度与发射体的过密度弱相关：在z=2.23时，过密度区域中的发射体比欠密度区域中的发射体更进化。我们在我们的目标领域中发现了几个扩展HAE的例子，包括一个引人注目的例子，在2 QZ领域中的空间范围为7.5 arcsec（z=2.23时为60 kpc），这表明这些在高密度区域中相对常见。我们的结论是，窄带H-α调查是有效的路线，以映射过密的区域在高Z，从而了解星系的生长和周围的大尺度结构之间的关系。
英文摘要：
We present the results of a narrow-band (H2S1, 2.121/0.021um) imaging search with WFCAM/UKIRT for H-alpha emitters around several potential signposts of rare (10^-7-10^-8 Mpc^-3) over-dense regions at z=2.23: an over-density of QSOs (2QZ cluster), a powerful, high-redshift radio galaxy (HzRG), and a concentration of submillimetre galaxies (SMGs) and optically faint radio galaxies (OFRGs). In total, we detect 137 narrow-band emitter candidates down to emission-line fluxes of 0.5-1 x 10^-16 erg s^-1 cm^-2, across a total area of 0.56 sq. degrees (2.1 x 10^5 comoving Mpc at z=2.23) in these fields. The BzK colours of the emitters suggest that at least 80% of our sample are likely to be H-alpha emitters (HAEs) at z=2.23. This is one of the largest HAE samples known at z>2. We find modest (~3-sigma) local over-densities of emitters associated with all the three targets. In the 2QZ cluster field, the emitters show a striking filamentary structure connecting four of the z=2.23 QSOs extending over 30Mpc (comoving). In the HzRG and SMG/OFRG fields, the structures appear to be smaller and seen only in the vicinities of the targets. The K-band magnitudes and the H-alpha equivalent widths of the emitters are weakly correlated with the over-density of the emitters: emitters in over-dense region are more evolved systems compared to those in under-dense regions at z=2.23. We find several examples of extended HAEs in our target fields, including a striking example with a spatial extent of 7.5 arcsec (60 kpc at z=2.23) in the 2QZ field, suggesting that these are relatively common in high-density regions. We conclude that narrow-band H-alpha surveys are efficient routes to map over-dense regions at high-z and thus to understand the relation between the growth of galaxies and their surrounding large-scale structures.
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