The non‐Gaussian cold spot in Wilkinson Microwave Anisotropy Probe: significance, morphology and foreground contribution

By M. Cruz, Marco Tucci, Enrique Martinez-Gonzalez, Patricio Vielva. 2006

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The non–Gaussian cold spot in the 1–year WMAP data, described in Vielva et al. and Cruz et al., is analysed in detail in the present paper. First of all, we perform a more rigorous calculation of the significance of the non–zero kurtosis detected in WMAP maps by Vielva et al. in wavelet space, mainly generated by the Spot. We confirm the robustness of that detection, since the probability of obtaining this deviation by chance is 0.69%. Afterwards, the morphology of the Spot is studied by applying Spherical Mexican Hat Wavelets with different ellipticities. The shape of the Spot is found to be almost circular. Finally, we discuss if the observed non–Gaussianity in wavelet space can arise from bad subtracted foreground residues in the WMAP maps. We show that the flat frequency dependence of the Spot cannot be explained by a thermal Sunyaev–Zeldovich effect. Based on our present knowledge of Galactic foreground emissions, we conclude that the significance of our detection is not affected by Galactic residues in the region of the Spot. Considering different Galactic foreground estimates, the probability of finding such a big cold spot in Gaussian simulations is always below 1%.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/294b1eb681e18a412dc1c54a459532d237471def

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Citations in the corpus

The Pantheon+ Analysis: Cosmological Constraints (2022, unknown): “The “CMB cold spot,” a 5° region of−70 μK centered at (l∼ 209°, b∼−57°), was first detected in data from the Wilkinson Microwave Anisotropy Probe (Vielva et al. 2004; Cruz et al. 2006), and subsequently in Planck data (Gurzadyan et al. 2014).”
Extragalactic Radio Sources and the WMAP Cold Spot (2007, methodology): “3) Similar results are found when using totally independent methods to model and subtract out the foreground emission (Cruz et al. 2006), namely the combined and foreground cleaned Q-V-W map (Bennett et al. 2003) and the weighted internal linear combination analysis (Tegmark et al. 2003).”
Confronting Lemaitre–Tolman–Bondi models with observational cosmology (2008, background): “This should not come as a surprise, we do live in an (locally) inhomogeneous universe, some say that within a large underdense void [6, 7, 8, 9, 10, 11] similar to that which induces a cold spot in the CMB [12, 13 , 14] so why should we assume global homogeneity? In fact, the possibility that we ha”
SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: ARE THERE COSMIC MICROWAVE BACKGROUND ANOMALIES? (2010, background): “Following up on this, Cruz et al. (2006) reported that the kurtosis in the wavelet distribution could be exclusively attributed to a single cold spot, which we call Cold Spot II, in the sky map at Galactic coordinates (l = 209◦, b = −57◦), as indicated by the red curve in Figure 2.”
INCREASING EVIDENCE FOR HEMISPHERICAL POWER ASYMMETRY IN THE FIVE-YEAR WMAP DATA (2009, background): “…violation of statistical isotropy in the WMAP data has grown very large, indeed (e.g., Bernui et al. 2006; Bielewicz et al. 2005; Copi et al. 2006; Cruz et al. 2005, 2006; Eriksen et al. 2004b,c, 2005; Jaffe et al. 2005, 2006; Mart́ınez-González et al. 2006; McEwen et al. 2008; Räth et al.…”
FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2008, unknown): “…et al. 2004; Schwarz et al. 2004; Copi et al. 2006, 2007; Gordon et al. 2005; Bielewicz et al. 2005; Jaffe et al. 2005, 2006; Vielva et al. 2004; Cruz et al. 2005, 2006, 2007b,a; Cayón et al. 2005; Bridges et al. 2007; Wiaux et al. 2008; Räth et al. 2007; Land & Magueijo 2005b,a, 2007; Rakić…”