Unexpected topology of the temperature fluctuations in the cosmic microwave background
| Autor: | Pratyush Pranav, Herbert Edelsbrunner, Hubert Wagner, Armin Schwartzman, Thomas Buchert, Bernard J. T. Jones, Rien van de Weygaert, Robert J. Adler |
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| Přispěvatelé: | Astronomy, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Gaussian Cosmic microwave background Cosmic background radiation FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics cosmic background radiation Topology 01 natural sciences Topological defect methods: numerical symbols.namesake 0103 physical sciences FOS: Mathematics Algebraic Topology (math.AT) Mathematics - Algebraic Topology Planck Instrumentation and Methods for Astrophysics (astro-ph.IM) 010303 astronomy & astrophysics Physics methods: statistical 010308 nuclear & particles physics Computer Science::Information Retrieval Spectral density Astronomy and Astrophysics early Universe CMB cold spot Space and Planetary Science symbols Anomaly (physics) [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] Astrophysics - Instrumentation and Methods for Astrophysics Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Astronomy and astrophysics, 627(July 2019):A163. EDP Sciences Astronomy and Astrophysics-A&A Astronomy and Astrophysics-A&A, EDP Sciences, 2019, 627, pp.A163. ⟨10.1051/0004-6361/201834916⟩ Astron.Astrophys. Astron.Astrophys., 2019, 627, pp.A163. ⟨10.1051/0004-6361/201834916⟩ Astronomy and Astrophysics-A&A, 2019, 627, pp.A163. ⟨10.1051/0004-6361/201834916⟩ Astronomy & Astrophysics |
| ISSN: | 0004-6361 |
| DOI: | 10.1051/0004-6361/201834916⟩ |
| Popis: | We study the topology generated by the temperature fluctuations of the Cosmic Microwave Background (CMB) radiation, as quantified by the number of components and holes, formally given by the Betti numbers, in the growing excursion sets. We compare CMB maps observed by the Planck satellite with a thousand simulated maps generated according to the LCDM paradigm with Gaussian distributed fluctuations. The survey of the CMB over $\mathbb{S}^2$ is incomplete due to obfuscation effects by bright point sources and other extended foreground objects like our own galaxy. To deal with such situations, where analysis in the presence of "masks" is of importance, we introduce the concept of relative homology. The parametric $\chi^2$-test shows differences between observations and simulations, yielding $p$-values at per-cent to less than per-mil levels roughly between 2 to 7 degrees. The highest observed deviation for $b_0$ and $b_1$ is approximately between $3\sigma$-4$\sigma$ at scales of 3 to 7 degrees. There are reports of mildly unusual behaviour of the Euler characteristic at 3.66 degrees in the literature, computed from independent measurements of the CMB temperature fluctuations by Planck's predecessor WMAP satellite. The mildly anomalous behaviour of Euler characteristic is related to the strongly anomalous behaviour of components and holes. These are also the scales at which the observed maps exhibit low variance compared to the simulations. Non-parametric tests show even stronger differences at almost all scales. Regardless, beyond the trivial possibility that this may still be a manifestation of an extreme Gaussian case, these observations, along with the super-horizon scales involved, may motivate to look at primordial non-Gaussianity. Alternative scenarios worth exploring may be models with non-trivial topology. Comment: 18 pages, 16 figures, 3 tables, submitted to Astronomy \& Astrophysics |
| Databáze: | OpenAIRE |
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