http://arxiv.org/abs/1701.08583
The integrated Sachs-Wolfe imprint of extreme structures in the cosmic web probes the dynamical nature of dark energy. Looking through typical cosmic voids, no anomalous signal has been reported. On the contrary, $super$voids, associated with large-scale fluctuations in the gravitational potential, have shown potentially disturbing excess signals. In this study, we used the Jubilee ISW simulation to demonstrate how the stacked signal depends on the void definition. We found that large underdensities, with at least $\sim5$ merged sub-voids, show a peculiar ISW imprint shape with central cold spots and surrounding hot rings, offering a natural way to define $super$voids in the cosmic web. We then inspected the real-world BOSS DR12 data using the simulated imprints as templates. The imprinted profile of BOSS $super$voids appears to be more compact than in simulations, requiring an extra $\alpha \approx 0.7$ re-scaling of filter sizes. The data reveals an excess ISW-$like$ signal with $A_{\rm ISW}\approx9$ amplitude at the $\sim2.5\sigma$ significance level, unlike previous studies that used isolated voids and reported good consistency with $A_{\rm ISW}=1$. The tension with the Jubilee-based $\Lambda$CDM predictions is $>2\sigma$, in consistency with independent analyses of $super$voids in Dark Energy Survey data. We show that such a very large enhancement of the $A_{\rm ISW}$ parameter hints at a possible causal relation between the CMB Cold Spot and the Eridanus $super$void. The origin of these findings remains unclear.
A. Kovacs
Tue, 31 Jan 17
28/58
Comments: 15 pages, 10 figures. Submitted to MNRAS
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