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arXiv · 1512.02694

Could multiple voids explain the Cosmic Microwave Background Cold Spot anomaly?

Krishna Naidoo·Aurélien Benoit-Lévy·Ofer Lahav
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Abstract

Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a > 3 sigma primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ~-50 mu K. In this model the central CS temperature lies at ~ 2 sigma but fails to explain the CS hot ring. An alternative multi-void model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multi-void scenarios) are removed. The CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.

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Krishna Naidoo, Aurélien Benoit-Lévy, Ofer Lahav. 2016-03-22. Could multiple voids explain the Cosmic Microwave Background Cold Spot anomaly?. https://doi.org/10.1093/mnrasl%2Fslw043

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