科研之友
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摘要
We present a simple gravitational lens model to illustrate the ease of using the embedded lensing theory when studying cosmic voids. It confirms the previously used repulsive lensing models for deep voids. We start by estimating magnitude fluctuations and weak-lensing shears of background sources lensed by large voids. We find that sources behind large (similar to 90 Mpc) and deep voids (density contrast about -0.9) can be magnified or demagnified with magnitude fluctuations of up to similar to 0.05 mag and that the weak-lensing shear can be up to the similar to 10(-2) level in the outer regions of large voids. Smaller or shallower voids produce proportionally smaller effects. We investigate the "wiggling" of the primary cosmic microwave background (CMB) temperature anisotropies caused by intervening cosmic voids. The void-wiggling of primary CMB temperature gradients is of the opposite sign to that caused by galaxy clusters. Only extremely large and deep voids can produce wiggling amplitudes similar to galaxy clusters, similar to 15 mu K by a large void of radius similar to 4 degrees and central density contrast -0.9 at redshift 0.5 assuming a CMB background gradient of similar to 10 mu K arcmin(-1). The dipole signal is spread over the entire void area, and not concentrated at the lens center as it is for clusters. Finally, we use our model to simulate CMB sky maps lensed by large cosmic voids. Our embedded theory can easily be applied to more complicated void models and used to study gravitational lensing of the CMB, to probe dark matter profiles, to reduce the lensing-induced systematics in supernova Hubble diagrams, and to study the integrated Sachs-Wolfe effect.
- 出版日期2015-5-10
