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arXiv 0911.4829astro-ph.COastro-ph.IM
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引力透镜类星体H1413 +117(立体式)的时间延迟

Time Delays in the Gravitationally Lensed Quasar H1413+117 (Cloverleaf)

Luis J. Goicoechea, Vyacheslav N. Shalyapin

摘要:

2008年2月至7月,利用2.0 m利物浦望远镜在斯隆波段对四重类星体H1413+117(z_s = 2.56)进行了观测。这种光学跟踪导致四个类星体图像(A-D)的精确光变曲线,这是由33个观测时期和\sim 15毫等的平均光度误差定义的。然后我们使用观察到的\sim 50-100 mmag的(固有)变化,以首次测量透镜系统的三个时间延迟(1σ置信区间):Δτ_{AB} = -17 +/- 3,Δτ_{AC} = -20 +/- 4,Δτ_{AD} = 23 +/- 4天(Δτ_{ij} = τ_j - τ_i; B和C领先,而D落后)。虽然透镜系统的时间延迟经常被用来获得哈勃常数(H_0),但是在系统H1413+117中光谱透镜红移(z_l)的不可用阻止了从测量的延迟确定H_0。在本文中,新的时间延迟约束和一致性扩展率(H_0 = 70 km s^{-1} Mpc^{-1})允许我们改进透镜模型和估计先前未知的z_l。我们的1σ估计z_l = 1.88^{+0.09}_{-0.11}是如何通过引力透镜推断非常遥远星系红移的一个例子。

英文摘要:

The quadruple quasar H1413+117 (z_s = 2.56) has been monitored with the 2.0 m Liverpool Telescope in the r Sloan band from 2008 February to July. This optical follow-up leads to accurate light curves of the four quasar images (A-D), which are defined by 33 epochs of observation and an average photometric error of \sim 15 mmag. We then use the observed (intrinsic) variations of \sim 50-100 mmag to measure the three time delays for the lens system for the first time (1σconfidence intervals): Δτ_{AB} = -17 +/- 3, Δτ_{AC} = -20 +/- 4, and Δτ_{AD} = 23 +/- 4 days (Δτ_{ij} = τ_j - τ_i; B and C are leading, while D is trailing). Although time delays for lens systems are often used to obtain the Hubble constant (H_0), the unavailability of the spectroscopic lens redshift (z_l) in the system H1413+117 prevents a determination of H_0 from the measured delays. In this paper, the new time delay constraints and a concordance expansion rate (H_0 = 70 km s^{-1} Mpc^{-1}) allow us to improve the lens model and to estimate the previously unknown z_l. Our 1σestimate z_l = 1.88^{+0.09}_{-0.11} is an example of how to infer the redshift of very distant galaxies via gravitational lensing.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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