COMAP Pathfinder – Season 2 results. II. Updated constraints on the CO(1–0) power spectrum

Creators: Stutzer, N.-O.¹; Lunde, J. G. S.¹; Breysse, P. C.^{2, 3}; Chung, D. T.^{4, 5, 6}; Cleary, K. A.⁷; Dunne, D. A.⁷; Eriksen, H. K.¹; Ihle, H. T.¹; Padmanabhan, H.⁸; Tolgay, D.^{4, 5}; Wehus, I. K.¹; Bond, J. R.^{4, 5}; Church, S. E.⁹; Gaier, T.¹⁰; Gundersen, J. O.¹¹; Harris, A. I.¹²; Harper, S. E.¹³; Hobbs, R.⁷; Kim, J.¹⁴; Lamb, J. W.⁷; Lawrence, C. R.¹⁰; Murray, N.^{4, 5}; Pearson, T. J.⁷; Philip, L.^{10, 15}; Readhead, Anthony C. S.⁷; Rennie, T. J.^{13, 16}; Woody, D. P.⁷; COMAP Collaboration

1. University of Oslo
2. New York University
3. Southern Methodist University
4. Canadian Institute for Theoretical Astrophysics
5. University of Toronto
6. Cornell University
7. California Institute of Technology
8. University of Geneva
9. Stanford University
10. Jet Propulsion Lab
11. University of Miami
12. University of Maryland, College Park
13. University of Manchester
14. Korea Advanced Institute of Science and Technology
15. Brookhaven National Laboratory
16. University of British Columbia

Abstract

We present updated constraints on the cosmological 3D power spectrum of carbon monoxide CO(1–0) emission in the redshift range 2.4–3.4. The constraints are derived from the two first seasons of Carbon monOxide Mapping Array Project (COMAP) Pathfinder line intensity mapping observations aiming to trace star formation during the epoch of galaxy assembly. These results improve on the previous Early Science results through both increased data volume and an improved data processing methodology. On the methodological side, we now perform cross-correlations between groups of detectors ("feed groups"), as opposed to cross-correlations between single feeds, and this new feed group pseudo power spectrum (FGPXS) is constructed to be more robust against systematic effects. In terms of data volume, the effective mapping speed is significantly increased due to an improved observational strategy as well as a better data selection methodology. The updated spherically and field-averaged FGPXS,C~(k), is consistent with zero, at a probability-to-exceed of around 34%, with an excess of 2.7σin the most sensitive bin. Our power spectrum estimate is about an order of magnitude more sensitive in our six deepest bins across 0.09 Mpc−1

Copyright and License

© The Authors 2024. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

We 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. 772253 bits2cosmology and 819478 Cosmoglobe). This material is based upon work supported by the National Science Foundation under Grant Nos. 1517108, 1517288, 1517598, 1518282, 1910999, and 2206834, as well as 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. PCB is supported by the James Arthur Postdoctoral Fellowship HP acknowledges support from the Swiss National Science Foundation via Ambizione Grant PZ00P2_179934. JK acknowledges support from a Robert A. Millikan Fellowship while at Caltech. DC 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. Research in Canada is supported by NSERC and CIFAR. SEH acknowledges funding from an STFC Consolidated Grant (ST/P000649/1) and a UKSA grant (ST/Y005945/1) funding LiteBIRD foreground activities. JG acknowledges support from the Keck Institute for Space Science, NSF AST-1517108, and University of Miami, and Hugh Medrano for assistance with cryostat design. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korean government(MSIT) (RS-2024-00340759). NOS and JGSL extend a great thanks to Sigurd K. Næss for all the fruitful discussions in the office, and while biking through nature, during the last three years. This work was first presented at the Line Intensity Mapping 2024 conference held in Urbana, Illinois; we thank the organizers for their hospitality and the participants for useful discussions.

Software References

Software acknowledgments. Matplotlib for plotting (Hunter 2007); NumPy (Harris et al. 2020) and SciPy (Virtanen et al. 2020) for efficient numerics and array handling in Python; Astropy a community-made core Python package for astronomy (Astropy Collaboration 2013, 2018, 2022); Multi-node parallelization with MPI for Python (Dalcín et al. 2005, 2008; Dalcin et al. 2011; Dalcin & Fang 2021); Pixell (https://github.com/simonsobs/pixell) for handling sky maps in rectangular pixelization.

Additional Information

Published together:

COMAP Pathfinder – Season 2 results. I. Improved data selection and processing. https://doi.org/10.1051/0004-6361/202451121
COMAP Pathfinder – Season 2 results. II. Updated constraints on the CO(1–0) power spectrum. https://doi.org/10.1051/0004-6361/202451123
COMAP Pathfinder – Season 2 results. III. Implications for cosmic molecular gas content at z ~ 3. https://doi.org/10.1051/0004-6361/202451122.

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