The XFaster Power Spectrum and Likelihood Estimator for the Analysis of Cosmic Microwave Background Maps

Creators: Gambrel, A. E.; Rahlin, A. S.; Song, X.; Contaldi, C. R.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bergman, A. S.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bonetti, J. A.; Bryan, S. A.; Chiang, H. C.; Duivenvoorden, A. J.; Eriksen, H. K.; Farhang, M.; Filippini, J. P.; Fraisse, A. A.; Freese, K.; Galloway, M. M.; Gandilo, N. N.; Gualtieri, R.; Gudmundsson, J. E.; Halpern, M.; Hartley, J.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Huang, Z.; Irwin, K. D.; Jones, W. C.; Karakci, A.; Kuo, C. L.; Kermish, Z. D.; Leung, J. S.-Y.; Li, S.; Mak, D. S. Y.; Mason, P. V.; Megerian, K.; Moncelsi, L.; Morford, T. A.; Nagy, J. M.; Netterfield, C. B.; Nolta, M.; O'Brient, R.; Osherson, B.; Padilla, I. L.; Racine, B.; Reintsema, C.; Ruhl, J. E.; Ruud, T. M.; Shariff, J. A.; Shaw, E. C.; Shiu, C.; Soler, J. D.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; van der List, J. F.; Weber, A. C.; Wehus, I. K.; Wen, S.; Wiebe, D. V.; Young, E. Y.

Abstract

We present the XFaster analysis package, a fast, iterative angular power spectrum estimator based on a diagonal approximation to the quadratic Fisher matrix estimator. It uses Monte Carlo simulations to compute noise biases and filter transfer functions and is thus a hybrid of both Monte Carlo and quadratic estimator methods. In contrast to conventional pseudo-Cℓ–based methods, the algorithm described here requires a minimal number of simulations and does not require them to be precisely representative of the data to estimate accurate covariance matrices for the bandpowers. The formalism works with polarization-sensitive observations and also data sets with identical, partially overlapping, or independent survey regions. The method was first implemented for the analysis of BOOMERanG data and also used as part of the Planck analysis. Here we describe the full, publicly available analysis package, written in Python, as developed for the analysis of data from the 2015 flight of the Spider instrument. The package includes extensions for self-consistently estimating null spectra and estimating fits for Galactic foreground contributions. We show results from the extensive validation of XFaster using simulations and its application to the Spider data set.

Additional Information

© 2021. The American Astronomical Society. Received 2021 May 21; revised 2021 August 24; accepted 2021 August 24; published 2021 November 25. We acknowledge the contribution to the development of the XFaster pipeline by all members of the BOOMERanG, Planck, and Spider collaborations. Spider is supported in the U.S. by the National Aeronautics and Space Administration under grants NNX07AL64G, NNX12AE95G, and NNX17AC55G issued through the Science Mission Directorate and by the National Science Foundation through PLR-1043515. Logistical support for the Antarctic deployment and operations is provided by the NSF through the U.S. Antarctic Program. Support in Canada is provided by the Natural Sciences and Engineering Research Council and the Canadian Space Agency. Support in Norway is provided by the Research Council of Norway. Support in Sweden is provided by the Swedish Research Council through the Oskar Klein Centre (contract No. 638-2013-8993), as well as a grant from the Swedish Research Council (dnr. 2019-93959) and a grant from the Swedish Space Agency (dnr. 139/17). The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. The multiplexing readout electronics were developed with support from the Canada Foundation for Innovation and the British Columbia Knowledge Development Fund. A.E.G. is supported by the Kavli Institute for Cosmological Physics at the University of Chicago through an endowment from the Kavli Foundation and its founder, Fred Kavli. C.R.C. was supported by UKRI consolidated grants ST/P000762/1, ST/N000838/1, and ST/T000791/1. K.F. holds the Jeff and Gail Kodosky Endowed Chair at UT Austin and is grateful for that support. W.C.J. acknowledges the generous support of the David and Lucile Packard Foundation, which has been crucial to the success of the project. Some of the results in this paper have been derived using the HEALPix package (Gorski et al. 2005). The computations described in this paper were performed on four computing clusters: Hippo at the University of KwaZulu-Natal, Feynman at Princeton University, and the GPC and Niagara supercomputers at the SciNet HPC Consortium (Loken et al. 2010; Ponce et al. 2019). SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada, the Government of Ontario, Ontario Research Fund–Research Excellence, and the University of Toronto. The collaboration is grateful to the British Antarctic Survey, particularly Sam Burrell, and the Alfred Wegener Institute and the crew of R.V. Polarstern for invaluable assistance with the recovery of the data and payload after the 2015 flight. Brendan Crill and Tom Montroy made significant contributions to Spider's development. This project, like so many others that he founded and supported, owes much to the vision and leadership of the late Professor Andrew E. Lange.

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