All sky CMB map from cosmic strings integrated Sachs-Wolfe effect

TL;DR

This paper presents the first high-resolution full-sky CMB map induced by cosmic strings, enabling better calibration of non-Gaussianity estimators and improving understanding of cosmic string effects on the CMB.

Contribution

The authors generated the first high-resolution full-sky CMB map from cosmic strings using a massively parallel ray tracing method and state-of-the-art simulations.

Findings

Map contains about 200 million pixels at sub-arcminute resolution.

Map corrects previous flat sky approximation results.

Generation required approximately 800,000 CPU hours.

Abstract

By actively distorting the Cosmic Microwave Background (CMB) over our past light cone, cosmic strings are unavoidable sources of non-Gaussianity. Developing optimal estimators able to disambiguate a string signal from the primordial type of non-Gaussianity requires calibration over synthetic full sky CMB maps, which till now had been numerically unachievable at the resolution of modern experiments. In this paper, we provide the first high resolution full sky CMB map of the temperature anisotropies induced by a network of cosmic strings since the recombination. The map has about 200 million sub-arcminute pixels in the healpix format which is the standard in use for CMB analyses (Nside=4096). This premiere required about 800,000 cpu hours; it has been generated by using a massively parallel ray tracing method piercing through a thousands of state of art Nambu-Goto cosmic string numerical simulations which pave the comoving volume between the observer and the last scattering surface. We explicitly show how this map corrects previous results derived in the flat sky approximation, while remaining completely compatible at the smallest scales.