An improved source-subtracted and destriped 408-MHz all-sky map

• Published in: Monthly notices of the Royal Astronomical Society Vol. 451; no. 4; p. 4300
• Main Authors: Remazeilles, M, Dickinson, C, Banday, A J, Bigot-Sazy, M-A, Ghosh, T
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01.08.2015
• Subjects: Cosmic microwave background temperature; Diffusion; Filtering; Fittings; Fluctuation; Impact analysis; Simulation; Single sex education; Stars & galaxies; Striations; Surveys; Symbols
• ISSN: 0035-8711; 1365-2966

The all-sky 408 MHz map of Haslam et al. is one the most important total-power radio surveys. It has been widely used to study diffuse synchrotron radiation from our Galaxy and as a template to remove foregrounds in cosmic microwave background data. However, there are a number of issues associated with it that must be dealt with, including large-scale striations and contamination from extragalactic radio sources. We have re-evaluated and reprocessed the rawest data available to produce a new and improved 408-MHz all-sky map. We first quantify the positional accuracy (...7 arcmin) and effective beam (56.0 plus or minus 1.0 arcmin) of the four individual surveys from which it was assembled. Large-scale striations associated with 1/f noise in the scan direction are reduced to a level ...1 K using a Fourier-based filtering technique. The most important improvement results from the removal of extragalactic sources. We have used an iterative combination of two techniques - two-dimensional Gaussian fitting and minimum curvature spline surface inpainting - to remove the brightest sources (... Jy), which provides a significant improvement over previous versions of the map. We quantify the impact with power spectra and a template fitting analysis of foregrounds to the WMAP data. The new map is publicly available and is recommended as the template of choice for large-scale diffuse Galactic synchrotron emission. We also provide a higher resolution map with small-scale fluctuations added, assuming a power-law angular power spectrum down to the pixel scale (1.7 arcmin). This should prove useful in simulations used for studying the feasibility of detecting H I fluctuations from the Epoch of Reionization. (ProQuest: ... denotes formulae/symbols omitted.)