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The weak-lensing masses of filaments between luminous red galaxies

zhpd55 添加于 2017/4/14 9:15:03  288次阅读 | 0次推荐 | 0个评论

In the standard model of non-linear structure formation, a cosmic web of dark-matter-dominated filaments connects dark matter haloes. In this paper, we stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, we detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between Sloan Digital Sky Survey (SDSS)-III/Baryon Oscillation Spectroscopic Survey luminous red galaxies (LRGs). As a control, we compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. We detect the excess filament mass density in the projected pairs at the 5σ level, finding a mass of (1.6 ± 0.3) × 10^{13} M⊙ for a stacked filament region 7.1 h^{−1} Mpc long and 2.5 h^{−1} Mpc wide. This filament signal is compared with a model based on the three-point galaxy–galaxy-convergence correlation function, as developed in Clampitt et al., yielding reasonable agreement.

作 者:Seth D. Epps, Michael J. Hudson
期刊名称: Mon Not R Astron Soc
期卷页: Published: 01 March 2017 第468卷 第3期 2605-2613页
学科领域:数理科学 » 天文学 » 星系和类星体
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原文链接:https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx517
DOI: https://doi.org/10.1093/mnras/stx517
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关键词: gravitational lensing: weak, galaxies: elliptical and lenticular, cD, dark matter, large-scale structure of Universe
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备 注: Researchers at the University of Waterloo have been able to capture the first composite image of a dark matter bridge that connects galaxies together. The scientists publish their work in a new paper in Monthly Notices of the Royal Astronomical Society. The composite image, which combines a number of individual images, confirms predictions that galaxies across the universe are tied together through a cosmic web connected by dark matter that has until now remained unobservable. Dark matter, a mysterious substance that comprises around 25 per cent of the universe, doesn't shine, absorb or reflect light, which has traditionally made it largely undetectable, except through gravity. "For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together," said Mike Hudson, a professor of astronomy at the University of Waterloo. "This image moves us beyond predictions to something we can see and measure." As part of their research, Hudson and co-author Seth Epps, a master's student at the University of Waterloo at the time, used a technique called weak gravitational lensing, an effect that causes the images of distant galaxies to warp slightly under the influence of an unseen mass such as a planet, a black hole, or in this case, dark matter. The effect was measured in images from a multi-year sky survey at the Canada-France-Hawaii Telescope. They combined lensing images from more than 23,000 galaxy pairs located 4.5 billion light-years away to create a composite image or map that shows the presence of dark matter between the two galaxies. Results show the dark matter filament bridge is strongest between systems less than 40 million light years apart. "By using this technique, we're not only able to see that these dark matter filaments in the universe exist, we're able to see the extent to which these filaments connect galaxies together," said Epps.
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