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A Model of Spectral Line Broadening in Signal Forecasts for Line-intensity Mapping Experiments

Chung, Dongwoo T. and Breysse, Patrick C. and Ihle, Håvard T. and Padmanabhan, Hamsa and Silva, Marta B. and Bond, J. Richard and Borowska, Jowita and Cleary, Kieran A. and Eriksen, Hans Kristian and Foss, Marie Kristine and Gundersen, Joshua Ott and Keating, Laura C. and Sturtzel Lunde, Jonas Gahr and Philip, Liju and Stutzer, Nils-Ole and Viero, Marco P. and Watts, Duncan J. and Wehus, Ingunn Kathrine (2021) A Model of Spectral Line Broadening in Signal Forecasts for Line-intensity Mapping Experiments. Astrophysical Journal, 923 (2). Art. No. 188. ISSN 0004-637X. doi:10.3847/1538-4357/ac2a35.

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Line-intensity mapping observations will find fluctuations of integrated line emission are attenuated by varying degrees at small scales due to the width of the line emission profiles. This attenuation may significantly impact estimates of astrophysical or cosmological quantities derived from measurements. We consider a theoretical treatment of the effect of line broadening on both the clustering and shot-noise components of the power spectrum of a generic line-intensity power spectrum using a halo model. We then consider possible simplifications to allow easier application in analysis, particularly in the context of inferences that require numerous, repeated, fast computations of model line-intensity signals across a large parameter space. For the CO Mapping Array Project and the CO(1–0) line-intensity field at z ∼ 3 serving as our primary case study, we expect a ∼10% attenuation of the spherically averaged power spectrum on average at relevant scales of k ≈ 0.2–0.3 Mpc⁻¹ compared to ∼25% for the interferometric Millimetre-wave Intensity Mapping Experiment targeting shot noise from CO lines at z ∼ 1–5 at scales of k ≳ 1 Mpc⁻¹. We also consider the nature and amplitude of errors introduced by simplified treatments of line broadening and find that while an approximation using a single effective velocity scale is sufficient for spherically averaged power spectra, a more careful treatment is necessary when considering other statistics such as higher multipoles of the anisotropic power spectrum or the voxel intensity distribution.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Chung, Dongwoo T.0000-0003-2618-6504
Breysse, Patrick C.0000-0001-8382-5275
Ihle, Håvard T.0000-0003-3420-7766
Padmanabhan, Hamsa0000-0002-8800-5740
Silva, Marta B.0000-0003-0209-4816
Bond, J. Richard0000-0003-2358-9949
Eriksen, Hans Kristian0000-0003-2332-5281
Keating, Laura C.0000-0001-5211-1958
Watts, Duncan J.0000-0002-5437-6121
Wehus, Ingunn Kathrine0000-0003-3821-7275
Additional Information:© 2021. The American Astronomical Society. Received 2021 April 22; revised 2021 September 17; accepted 2021 September 24; published 2021 December 21. 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. K.C. acknowledges support from the National Science Foundation under grant Nos. 1518282 and 1910999. Work at the University of Oslo is supported by the Research Council of Norway through grant 251328. H.P. acknowledges support from the Swiss National Science Foundation through Ambizione grant PZ00P2_179934. J.O.G. acknowledges support from the Keck Institute for Space Studies, NSF AST-1517108, and the University of Miami. L.C.K. was supported by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 885990. Thanks to Sarah Church and Karto Keating for early discussions that motivated and informed the present work, and to Tim Pearson and other members of the COMAP collaboration for helpful comments on the manuscript. We thank Matthew Becker and Risa Wechsler for access to the Chinchilla cosmological simulation (c400-2048) used in this work. We thank Riccardo Pavesi for access to the COLDz ABC posterior sample used in this work. COMAP is supported by the National Science Foundation under grant No. 1910999. This research made use of NASA's Astrophysics Data System Bibliographic Services. Some of the computing for this project was performed on the Sherlock cluster. D.T.C. would like to thank Stanford University and the Stanford Research Computing Center for providing computational resources and support that contributed to these research results. Part of this work was shown pre-publication at the 2021 Line Intensity Mapping Workshop hosted by the University of Chicago and the Kavli Institute for Cosmological Physics, whose (virtual) hospitality we gratefully acknowledge. Finally, we thank an anonymous referee whose comments helped improve the manuscript. Software: hmf(Murray et al. 2013); Matplotlib(Hunter 2007); Astropy, a community-developed core Python package for astronomy (Astropy Collaboration et al. 2013).
Group:Keck Institute for Space Studies
Funding AgencyGrant Number
Canadian Institute for Theoretical AstrophysicsUNSPECIFIED
Dunlap Institute for Astronomy and AstrophysicsUNSPECIFIED
University of TorontoUNSPECIFIED
Research Council of Norway251328
Swiss National Science Foundation (SNSF)PZ00P2_179934
Keck Institute for Space Studies (KISS)UNSPECIFIED
University of MiamiUNSPECIFIED
Marie Curie Fellowship885990
Subject Keywords:High-redshift galaxies; Radio astronomy; CO line emission
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: High-redshift galaxies (734); Radio astronomy (1338); CO line emission (262)
Record Number:CaltechAUTHORS:20211221-473273000
Persistent URL:
Official Citation:Dongwoo T. Chung et al 2021 ApJ 923 188
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112609
Deposited By: George Porter
Deposited On:21 Dec 2021 21:58
Last Modified:21 Dec 2021 21:58

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