Information theoretic bounds on cosmic string detection in CMB maps with noise
Abstract
We use a convolutional neural network to study cosmic string detection in cosmic microwave background (CMB) flat sky maps with NambuGoto strings. On noiseless maps, we can measure string tensions down to order 10^{9}, however when noise is included we are unable to measure string tensions below 10^{7}. Motivated by this impasse, we derive an information theoretic bound on the detection of the cosmic string tension Gμ from CMB maps. In particular, we bound the information entropy of the posterior distribution of Gμ in terms of the resolution, noise level and total survey area of the CMB map. We evaluate these bounds for the ACT, SPT3G, Simons Observatory, Cosmic Origins Explorer, and CMBS4 experiments. These bounds cannot be saturated by any method.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 February 2020
 DOI:
 10.1093/mnras/stz3551
 arXiv:
 arXiv:1911.06378
 Bibcode:
 2020MNRAS.492.1329C
 Keywords:

 methods: data analysis;
 methods: statistical;
 cosmic background radiation;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 v3: corrected error in table 1 entry for the CORE experiment. This matches the erratum submitted for the version published in MNRAS. 7 pages, 1 figure, 1 table