Could multiple voids explain the cosmic microwave background Cold Spot anomaly?
Abstract
Understanding the observed Cold Spot (CS, temperature of ∼ - 150 μK at its centre) on the cosmic microwave background is an outstanding problem. Explanations vary from assuming it is just a ≳3σ 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 μK. In this model the central CS temperature lies at ∼2σ but fails to explain the CS hot ring. An alternative multivoid 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 multivoid scenarios) are removed. The CS tension with the Λ cold dark matter model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2016
- DOI:
- 10.1093/mnrasl/slw043
- arXiv:
- arXiv:1512.02694
- Bibcode:
- 2016MNRAS.459L..71N
- Keywords:
-
- cosmic background radiation;
- large-scale structure of Universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 5 pages, 3 figures, as appears in MNRAS Letters