How many arcmin-separation lenses are expected in the 2dF QSO survey?
How many arcmin-separation lenses are expected in the 2dF QSO survey?
复制标题
2dF QSO 调查中预计有多少个 arcmin 分离镜头？
DOI：
10.1046/j.1365-8711.2003.06384.x
复制
发表时间：
2002
影响因子：
4.8
通讯作者：
M. Oguri
中科院分区：
文献类型：
--
作者：
M. Oguri
宽间隔透镜统计提供了有关密度分布和暗晕丰度的信息。米勒等人最近报道了可能发现的六对类星体对，它们可能是多重像透镜。这些对是从2dF类星体（QSO）调查包括22163类星体的目录中选择的。考虑到类星体目录的红移和星等分布，我们计算了透镜类星体的预期数量。考虑到六对中的一些是真正的透镜系统，我们对暗晕的内斜率Ω 0和σ 8施加了有趣的限制。我们发现，即使是一个透镜与分离> 30弧秒的检测是勉强一致的模型，具有尖形的内部密度分布，PR- 1。当Ω 0 = 0.3时，σ 8很大，σ 8 ≥ 1.2。为了与X射线团或宇宙剪切的约束相协调，需要更低的Ω 0和更高的σ 8值，尽管如此高的σ 8值似乎太极端了。较浅的内部密度分布pr- 1几乎是不可接受的。特别是，分离度>200弧秒的透镜的预期数量太少，无法解释这种非常宽的分离度透镜系统的发现。这些结果意味着我们错过了一些重要的系统效应，在冷暗物质场景中存在问题，或者这六个类星体对中没有一个可能是透镜图像。
Wide-separation lensing statistics offer information about the density profile and abundance of dark haloes. A possible discovery of six quasar pairs, which may be lensed multiple images, was reported by Miller et al. recently. These pairs are selected from a catalogue of the 2dF quasar (QSO) survey comprising 22163 quasars. We calculate expected numbers of lensed quasars taking account of the redshift and magnitude distributions of the quasar catalogue. Given some of the six pairs are genuine lensed systems, we put interesting constraints on the inner slope of dark haloes, Ω 0 and σ 8 . We show that the detection of even one lens with separation > 30 arcsec is marginally consistent with models that have cuspy inner density profile, p r - 1 . 5 and very large σ 8 , σ 8 ≥ 1.2 for Ω 0 = 0.3. To reconcile with constraints from X-ray clusters or cosmic shear, much lower Ω 0 and much higher σ 8 values are needed, although such high values for σ 8 seem too extreme. The shallower inner density profile p r - 1 is hardly acceptable. In particular, the expected number of lenses with separation >200 arcsec is too small to explain the discovery of such anomalously wide-separation lens systems. These results imply that we miss some important systematic effects, there is a problem in the cold dark matter scenario, or none of these six quasar pairs is likely to be a lensed image.
DOI：
10.1046/j.1365-8711.2001.04029.x
发表时间：
2001-02-21
影响因子：
4.8
作者：
Jenkins, A;Frenk, CS;Yoshida, N
通讯作者：
Yoshida, N