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arXiv 1302.2607astro-ph.CO
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内禀排列星系的弱引力透镜

Weak gravitational lensing of intrinsically aligned galaxies

Aram Giahi-Saravani, Bjoern Malte Schaefer

摘要:

本文的研究对象是具有内相关椭率的星系的弱透镜效应。在我们的模型中,我们调查的椭圆率场的扭曲,如果星系经历了一个明显的移动,在他们的位置由弱透镜偏转和比较这种效果的剪切效应引起的潮汐场。从推导的内禀椭圆率谱采用潮汐扭矩模型产生的银河系角动量,我们的模型的星系椭圆率假设银河系盘形成垂直于主机晕角动量方向和推导的内禀椭圆率E-模式和B-模式的角动量统计光谱。椭圆率场的透镜效应是通过采用在宇宙微波背景偏振透镜的框架内开发的方法来模拟的。对于EUCLID,在多极l>1000上的透镜偏转改变了椭圆度相关性,对于椭圆度E模式约为5%,对于B模式约为30%,而较浅的调查将在较大的角度尺度上表现出较大的变化。除了椭圆率谱上的透镜的卷积效应,我们调查的E/B模式转换,并讨论测量不同的多极子之间的相关性,这是由均匀性破坏效应的透镜位移引起的可能性。我们的结论是,虽然弱引力剪切产生的形状相关性是占主导地位的,由于透镜的移位效应是塑造小角度尺度上的椭圆率谱,并导致一些有趣的现象,这可能是观察到的未来的调查。

英文摘要:

Subject of this paper is the weak lensing effect on galaxies that show intrinsically correlated ellipticities. In our model, we investigate the distortion of the ellipticity field if the galaxies experience an apparent shift in their position by weak lensing deflection and compare this effect to the shearing effect induced by tidal fields. Starting with a derivation of intrinsic ellipticity spectra by employing a tidal torquing model generating galactic angular momenta, we model the galaxy ellipticity by assuming that the galactic disk forms perpendicularly to the host halo angular momentum direction and derive intrinsic ellipticity E-mode and B-mode spectra from the angular momentum statistics. The lensing effect on the ellipticity field is modeled by employing the methodology developed in the framework of lensing of the cosmic microwave background polarisation. For EUCLID, ellipticity correlations are altered by lensing deflection on multipoles l>1000 by ~5% for the ellipticity E-modes and by ~30% for the B-modes, while a shallower survey would exhibit larger changes on larger angular scales. In addition to the convolving effect of lensing on the ellipticity spectra we investigate the E/B-mode conversion, and discuss the possibility of measuring correlations between different multipoles which is evoked by the homogeneity breaking effect of the lensing displacement. Our conclusion is that although shape correlations generated by weak gravitational shear is dominant, the shifting effect due to lensing is shaping the ellipticity spectra on small angular scales and causes a number of interesting phenomena, which might be observable by future surveys.

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