论文标题
Vandels调查：在Z> 2处发现大量星系过度过度
The VANDELS survey: Discovery of massive overdensities of galaxies at z>2
论文作者
论文摘要
我们想调查是否可以使用Lyalpha排放来获取有关环境特性的信息，以及Lyalpha发射器是否显示出不同的特征作为其环境的函数。我们通过使用在RA-DEC-REDSHIFT空间中起作用的三维算法，估计了Vandla Chandra Deep-South（CDFS）和Ukidss Ulta Deep Survey（UDS）领域的局部密度。我们选择了对环境密度无偏见的131个发光星系（EW（lyalpha）> 0 a）的样品，以研究其相对于过度或不密度的环境的位置。我们基于来自Vandels和所有可用文献的光度和光谱红移，在2 <Z <4中识别CDF中的13个（原始）群集候选。在所确定的过度度中的田间和星系之间的静电帧U-V颜色中未观察到显着差异。我们发现Vandels Lyalpha发射器（LAEVS）优先地躺在过度密度的地区，因为大多数带有来自Vandels的光谱红移的星系。过度密度区域中的LAEV往往具有低质量等效宽度和低特异性SFR，并且它们也比该领域的LAEV更大。他们堆叠的Lyalpha曲线显示出主要的红色峰和蓝色峰的暗示。我们的结果表明，LAEVS可能会受到环境的影响，并偏向于低膨胀速度的流出和过度密度区域中星系的高柱密度的流出。膨胀速度低的流出可能与星系在过度密度区域形成恒星的方式有关；高HI柱密度可能是过度密度的重力电势的结果。因此，发射Lyalpha的星系可以为其居住的环境提供有用的见解。
We want to investigate whether we can use Lyalpha emission to obtain information on the environment properties and whether Lyalpha emitters show different characteristics as a function of their environment. We estimated local densities in the VANDELS Chandra Deep Field-South (CDFS) and UKIDSS Ultra Deep Survey (UDS) fields, by using a three-dimensional algorithm which works in the RA-dec-redshift space. We selected a sample of 131 Lyalpha-emitting galaxies (EW(Lyalpha)>0 A), unbiased with respect to environmental density, to study their location with respect to the over- or under-dense environment. We identify 13 (proto)cluster candidates in the CDFS and nine in the UDS at 2<z<4, based on photometric and spectroscopic redshifts from VANDELS and from all the available literature. No significant difference is observed in the rest-frame U-V color between field and galaxies located within the identified overdensities. We find that VANDELS Lyalpha emitters (LAEVs) lie preferentially outside of overdense regions as the majority of the galaxies with spectroscopic redshifts from VANDELS. The LAEVs in overdense regions tend to have low Lyalpha equivalent widths and low specific SFRs, and they also tend to be more massive than the LAEVs in the field. Their stacked Lyalpha profile shows a dominant red peak and a hint of a blue peak. Our results show that LAEVs are likely to be influenced by the environment and favour a scenario with outflows of low expansion velocities and high HI column densities for galaxies in overdense regions. An outflow with low expansion velocity could be related to the way galaxies are forming stars in overdense regions; the high HI column density can be a consequence of the gravitational potential of the overdensity. Therefore, Lyalpha-emitting galaxies can provide useful insights on the environment in which they reside.
