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COMAP Early Science. IV. Power Spectrum Methodology and Results

Ihle, Håvard T. and Borowska, Jowita and Cleary, Kieran A. and Eriksen, Hans Kristian and Foss, Marie K. and Harper, Stuart E. and Kim, Junhan and Lunde, Jonas G. S. and Philip, Liju and Rasmussen, Maren and Stutzer, Nils-Ole and Uzgil, Bade D. and Watts, Duncan J. and Wehus, Ingunn Kathrine and Bond, J. Richard and Breysse, Patrick C. and Catha, Morgan and Church, Sarah E. and Chung, Dongwoo T. and Dickinson, Clive and Dunne, Delaney A. and Gaier, Todd and Gundersen, Joshua Ott and Harris, Andrew I. and Hobbs, Richard and Lamb, James W. and Lawrence, Charles R. and Murray, Norman and Readhead, Anthony C. S. and Padmanabhan, Hamsa and Pearson, Timothy J. and Rennie, Thomas J. and Woody, David P. (2022) COMAP Early Science. IV. Power Spectrum Methodology and Results. Astrophysical Journal, 933 (2). Art. No. 185. ISSN 0004-637X. doi:10.3847/1538-4357/ac63c5.

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We present the power spectrum methodology used for the first-season COMAP analysis, and assess the quality of the current data set. The main results are derived through the Feed–Feed Pseudo-Cross-Spectrum (FPXS) method, which is a robust estimator with respect to both noise modeling errors and experimental systematics. We use effective transfer functions to take into account the effects of instrumental beam smoothing and various filter operations applied during the low-level data processing. The power spectra estimated in this way have allowed us to identify a systematic error associated with one of our two scanning strategies, believed to be due to residual ground or atmospheric contamination. We omit these data from our analysis and no longer use this scanning technique for observations. We present the power spectra from our first season of observing, and demonstrate that the uncertainties are integrating as expected for uncorrelated noise, with any residual systematics suppressed to a level below the noise. Using the FPXS method, and combining data on scales k = 0.051–0.62 Mpc⁻¹, we estimate P_(CO(k)) = −2.7 ± 1.7 × 10⁴ μK² Mpc³, the first direct 3D constraint on the clustering component of the CO(1–0) power spectrum in the literature.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ihle, Håvard T.0000-0003-3420-7766
Cleary, Kieran A.0000-0002-8214-8265
Eriksen, Hans Kristian0000-0003-2332-5281
Foss, Marie K.0000-0001-8896-3159
Harper, Stuart E.0000-0001-7911-5553
Kim, Junhan0000-0002-4274-9373
Philip, Liju0000-0001-7612-2379
Stutzer, Nils-Ole0000-0001-5301-1377
Uzgil, Bade D.0000-0001-8526-3464
Watts, Duncan J.0000-0002-5437-6121
Wehus, Ingunn Kathrine0000-0003-3821-7275
Bond, J. Richard0000-0003-2358-9949
Breysse, Patrick C.0000-0001-8382-5275
Chung, Dongwoo T.0000-0003-2618-6504
Dickinson, Clive0000-0002-0045-442X
Dunne, Delaney A.0000-0002-5223-8315
Gundersen, Joshua Ott0000-0002-7524-4355
Harris, Andrew I.0000-0001-6159-9174
Lamb, James W.0000-0002-5959-1285
Readhead, Anthony C. S.0000-0001-9152-961X
Padmanabhan, Hamsa0000-0002-8800-5740
Pearson, Timothy J.0000-0001-5213-6231
Rennie, Thomas J.0000-0002-1667-3897
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 November 19; revised 2022 February 25; accepted 2022 March 25; published 2022 July 13. Focus on Early Science Results from the CO Mapping Array Project (COMAP). This material is based upon work supported by the National Science Foundation, under grant Nos. 1517108, 1517288, 1517598, 1518282, and 1910999, and by the Keck Institute for Space Studies, under "The First Billion Years: A Technical Development Program for Spectral Line Observations." Parts of the work were carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with the National Aeronautics and Space Administration, and funded through the internal Research and Technology Development program. D.T.C. is supported by a CITA/Dunlap Institute postdoctoral fellowship. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. C.D. acknowledges support from an STFC Consolidated Grant (ST/P000649/1). J.B., H.K.E., M.K.F., H.T.I., J.G.S.L., M.R., N.O.S., D.W., and I.K.W. acknowledge support from the Research Council of Norway through grants 251328 and 274990, and from the European Research Council (ERC) under the Horizon 2020 Research and Innovation Program (grant agreement No. 819478, Cosmoglobe). J.G. acknowledges support from the University of Miami and is grateful to Hugh Medrano for assistance with cryostat design. S.H. acknowledges support from an STFC Consolidated Grant (ST/P000649/1). J.K. is supported by a Robert A. Millikan Fellowship from Caltech. At JPL, we are grateful to Mary Soria for assembly work on the amplifier modules and to Jose Velasco, Ezra Long, and Jim Bowen for the use of their amplifier test facilities. H.P. acknowledges support from the Swiss National Science Foundation through Ambizione Grant PZ00P2_179934. P.C.B. is supported by the James Arthur Postdoctoral Fellowship. We thank Isu Ravi for her contributions to the warm electronics and antenna–driven characterization. The scientific color maps roma and tokyo (Crameri 2021) are used in this study to prevent visual distortion of the data and exclusion of readers with color-vision deficiencies (Crameri et al. 2020). Finally, we want to thank the anonymous referee, whose comments and suggestions have helped to improve and clarify this manuscript. Software: Matplotlib (Hunter 2007); Astropy, a community-developed core Python package for astronomy (Astropy Collaboration et al. 2013).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Keck Institute for Space Studies, Owens Valley Radio Observatory (OVRO)
Funding AgencyGrant Number
Keck Institute for Space Studies (KISS)UNSPECIFIED
JPL Internal Research and Technology Development ProgramUNSPECIFIED
Canadian Institute for Theoretical AstrophysicsUNSPECIFIED
Dunlap Institute for Astronomy and AstrophysicsUNSPECIFIED
University of TorontoUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/P000649/1
Research Council of Norway251328
Research Council of Norway274990
European Research Council (ERC)819478
University of MiamiUNSPECIFIED
Robert A. Millikan FellowshipUNSPECIFIED
Swiss National Science Foundation (SNSF)PZ00P2_179934
James Arthur FellowshipUNSPECIFIED
Subject Keywords:CO line emission; Cosmological evolution; High-redshift galaxies; Molecular gas; Radio astronomy
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: CO line emission (262); Cosmological evolution (336); High-redshift galaxies (734); Molecular gas (1073); Radio astronomy (1338)
Record Number:CaltechAUTHORS:20220727-38447000
Persistent URL:
Official Citation:Håvard T. Ihle et al 2022 ApJ 933 185
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115917
Deposited By: George Porter
Deposited On:28 Jul 2022 22:55
Last Modified:28 Jul 2022 22:55

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