Observations of the Corona Borealis supercluster with the superextended Very Small Array: further constraints on the nature of the non-Gaussian cosmic microwave background cold spot

Abstract

We present interferometric imaging at 33 GHz, with the new superextended configuration of the Very Small Array (VSA), of a very deep decrement in the cosmic microwave background (CMB) temperature. This decrement is located in the direction of the Corona Borealis supercluster, at a position with no known galaxy clusters, and was discovered by a previous VSA survey. A total area of 3 deg2 has now been imaged, with an angular resolution of 7 arcmin and a flux sensitivity of 5 mJy beam−1. These observations confirm the presence of this strong and resolved negative spot at −37 ± 5 mJy beam−1(−229 ± 32 μK). This structure is also present in the Wilkinson Microwave Anisotropy Probe 5‐year data. The temperature of the W‐band (94 GHz) data at the position of the decrement agrees within 0.3σn with that observed by the VSA at 33 GHz and within 0.2σn with the Sunyaev–Zel'dovich (SZ) spectrum. Our analyses show that it is a non‐Gaussian feature in the CMB at a level of 4.4σ, where sigma accounts for primordial CMB fluctuations, thermal noise and residual radio source contributions. The probability of finding such a deviation or larger in simulations including Gaussian CMB is only 0.63 per cent. Therefore, an explanation other than primordial Gaussian CMB is required. We have considered the possibility of an SZ effect generated in a diffuse, extended warm/hot gas distribution. This hypothesis is especially relevant, as the presence of such structures, if confirmed, could provide the location for a significant fraction of the missing baryons in the Local Universe. However, from the absence of X‐ray emission in this region we conclude that the whole decrement cannot be generated solely via the SZ effect in such structure. Therefore, the most plausible scenario is a combination between a negative CMB feature and a SZ effect, probably generated by a warm/hot gas distribution.

Some statistical remarks on the giant GRB ring

“…The large amount of excess gravitating matter would have an imprint on the cosmic microwave background (CMB) (Cruz et al 2008;Génova-Santos et al 2008;Masina & Notari 2009;Das & Spergel 2009;Padilla-Torres et al 2009;Masina & Notari 2009;Solov'ev & Verkhodanov 2010;Granett, Szapudi & Neyrinck 2010;Bremer et al 2010;Chingangbam et al 2012;Fernández-Cobos et al 2013;Kovács & Granett 2015;Kovács & García-Bellido 2016) due to the integrated Sachs-Wolfe effect (Sachs & Wolfe 1967). A shell would have a ring on the CMB.…”

Future virialized structures: an analysis of superstructures in the SDSS-DR7

“…Porter et al (2008) find that star formation is significantly enhanced when galaxies fall into clusters along supercluster filaments. Superclusters have also been studied as hosts of Lyα absorbers (Stocke et al 1995; Penton, Stocke & Shull 2002) and are known to produce signatures in the cosmic background radiation (Dolag et al 2005; Génova‐Santos et al 2008; Flores‐Cacho et al 2009; Granett, Neyrinck & Szapudi 2009; Génova‐Santos et al 2010).…”

Textures and semi-local strings in supersymmetric hybrid inflation

“…Such dynamically unstable defects produce a spectrum of anisotropies qualitatively similar to strings [22] and are likely to have similar properties in respect of the degeneracy with n s . We note, in addition, the other cold spots detected on smaller scale in the CMB which do not appear to be associated with the Sunyaev-Zel'dovich effect [23].…”