@article{pranav_loops_2021, abstract = {We present a topological analysis of the temperature fluctuation maps from the {\textbackslash}emph\{Planck 2020\} Data release 4 ({DR}4) based on the {\textbackslash}texttt\{{NPIPE}\} data processing pipeline. For comparison, we also present the topological characteristics of the maps from {\textbackslash}emph\{Planck 2018\} Data release 3 ({DR}3). We perform our analysis in terms of the homology characteristics of the maps, invoking relative homology to account for analysis in the presence of masks. We perform our analysis for a range of smoothing scales spanning sub- and super-horizon scales corresponding to \${FWHM} = 5', 10', 20', 40', 80', 160', 320', 640'\$. Our main result indicates a significantly anomalous behavior of the loops in the observed maps compared to simulations that are modeled as isotopic and homogeneous Gaussian random fields. Specifically, we observe a \$4{\textbackslash}sigma\$ deviation between the observation and simulations in the number of loops at \${FWHM} = 320'\$ and \${FWHM} = 640'\$, corresponding to super-horizon scales of \$5\$ degrees and larger. In addition, we also notice a mildly significant deviation at \$2{\textbackslash}sigma\$ for all the topological descriptors for almost all the scales analyzed. Our results show a consistency across different data releases, and therefore, the anomalous behavior deserves a careful consideration regarding its origin and ramifications. Disregarding the unlikely source of the anomaly being instrumental systematics, the origin of the anomaly may be genuinely astrophysical -- perhaps due to a yet unresolved foreground, or truly primordial in nature. Given the nature of the topological descriptors, that potentially encodes information of all orders, non-Gaussianities, of either primordial or late-type nature, may be potential candidates. Alternate possibilities include the Universe admitting a non-trivial global topology, including effects induced by large-scale topological defects.}, author = {Pranav, Pratyush}, date = {2021-01-06}, eprint = {2101.02237}, eprinttype = {arxiv}, journaltitle = {{arXiv}:2101.02237 [astro-ph]}, keywords = {1 - Astrophysics, 1 - Nongalactic astrophysics, 2 - Betti numbers, 2 - Persistent homology, 3 - Maps, 3 - Radiomic data set, 3 - Temperature}, shorttitle = {Loops abound in the cosmic microwave background}, title = {Loops abound in the cosmic microwave background: A \$4{\textbackslash}sigma\$ anomaly on super-horizon scales}, url = {http://arxiv.org/abs/2101.02237}, urldate = {2021-01-08} }