COMAP Early Science. II. Pathfinder Instrument

Creators: Lamb, James W.; Cleary, Kieran A.; Woody, David P.; Catha, Morgan; Chung, Dongwoo T.; Gundersen, Joshua Ott; Harper, Stuart E.; Harris, Andrew I.; Hobbs, Richard; Ihle, Håvard T.; Kocz, Jonathon; Pearson, Timothy J.; Philip, Liju; Powell, Travis W.; Basoalto, Lilian; Bond, J. Richard; Borowska, Jowita; Breysse, Patrick C.; Church, Sarah E.; Dickinson, Clive; Dunne, Delaney A.; Eriksen, Hans Kristian; Foss, Marie Kristine; Gaier, Todd; Kim, Junhan; Lawrence, Charles R.; Lunde, Jonas G. S.; Padmanabhan, Hamsa; Rasmussen, Maren; Readhead, Anthony C. S.; Reeves, Rodrigo; Rennie, Thomas J.; Stutzer, Nils-Ole; Viero, Marco P.; Watts, Duncan J.; Wehus, Ingunn Kathrine; COMAP Collaboration

Abstract

Line intensity mapping (LIM) is a new technique for tracing the global properties of galaxies over cosmic time. Detection of the very faint signals from redshifted carbon monoxide (CO), a tracer of star formation, pushes the limits of what is feasible with a total-power instrument. The CO Mapping Project Pathfinder is a first-generation instrument aiming to prove the concept and develop the technology for future experiments, as well as delivering early science products. With 19 receiver channels in a hexagonal focal plane arrangement on a 10.4 m antenna and an instantaneous 26–34 GHz frequency range with 2 MHz resolution, it is ideally suited to measuring CO (J = 1–0) from z ∼ 3. In this paper we discuss strategies for designing and building the Pathfinder and the challenges that were encountered. The design of the instrument prioritized LIM requirements over those of ancillary science. After a couple of years of operation, the instrument is well understood, and the first year of data is already yielding useful science results. Experience with this Pathfinder will guide the design of the next generations of experiments.

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 24; accepted 2021 December 18; published 2022 July 13. Focus on Early Science Results from the CO Mapping Array Project (COMAP). This material is based on 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, 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. and S.H. acknowledge 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. L.K. was supported by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 885990. J. Kim 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. R.R. acknowledges support from ANID-FONDECYT grant 1181620. M.V. acknowledges support from the Kavli Institute for Particle Astrophysics and Cosmology. We thank Isu Ravi for her contributions to the warm electronics and antenna drive characterization. We would also like to acknowledge the important contributions of Russell Keeney, Michael Virgin, and Andres Rizo for constructing and installing major mechanical parts of the instrument. We gratefully acknowledge hardware donations from Xilinx within the Xilinx University Program. Finally, we thank the anonymous referee for the careful reading of the manuscript.

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