We present some of the first infrared spectral maps acquired by SPHEREx. These maps, which to our knowledge are the largest of their type ever compiled in the near-infrared, reveal multiple strong lines due to interstellar ices and polycyclic aromatic hydrocarbons (PAHs) throughout the Cygnus X and North American Nebula regions. The maps emphasize the strongest features arising from the 3 μm H2O, 4.27 μm CO2, and 4.67 μm CO lines and the 3.28 μm PAH feature, all of which are detected over large areas with complex and filamentary spatial distributions. The ice absorption maps of H2O and CO2 in particular broadly trace dense, cold, and well-shielded regions across Cygnus X, consistent with the established picture of efficient ice formation in dense molecular clouds. The interstellar ice features are also detected abundantly in diffuse absorption over wide areas. The relative strengths of the H2O and CO2 features vary among different lines of sight, indicating possible differences in local physical conditions or chemical variations. The 3.28 μm PAH emission correlates with the emission from the 7.7 and 11.2 μm features but shows small differences that may trace the grain-size distribution and variations in the ambient UV field. SPHEREx all-sky spectral imaging—only a small fraction of which is showcased in this work—will support numerous science investigations, including the structure of the Galaxy, the physics of the interstellar medium, and the chemistry of stars.
SPHEREx Widefield Infrared Spectral Mapping of Interstellar Ices and Polycyclic Aromatic Hydrocarbons
Creators
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Hora, Joseph L.1
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Noh, Jinyoung K.2
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Melnick, Gary J.1
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Hensley, Brandon S.3
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Paladini, Roberta4
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Lee, Jeong-Eun2
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Ashby, Matthew L. N.1
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Tolls, Volker1
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Kim, Jaeyeong1, 5
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Werner, Michael W.3
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Bock, James J.3, 6
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Bruton, Sean6
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Chen, Shuang-Shuang6
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Chang, Tzu-Ching3, 6
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Chiang, Yi-Kuan7
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Cooray, Asantha8
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Crill, Brendan P.3, 6
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Cukierman, Ari J.6
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Doré, Olivier3, 6
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Faisst, Andreas L.4
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Huai, Zhaoyu6
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Hui, Howard6
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Jeong, Woong-Seob5
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Kang, Miju5
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Korngut, Phil M.6
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Lee, Ho-Gyu5
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Lisse, Carey M.9, 10
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Masters, Daniel C.4
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Murgia, Giulia6
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Nguyen, Chi H.6
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Rustamkulov, Zafar4
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Seok, Ji Yeon5
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Wen, Robin Y.6
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Yang, Yujin5
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Zemcov, Michael3, 11
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1.
Harvard-Smithsonian Center for Astrophysics
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2.
Seoul National University
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3.
Jet Propulsion Lab
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4.
Infrared Processing and Analysis Center
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5.
Korea Astronomy and Space Science Institute
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6.
California Institute of Technology
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7.
Institute of Astronomy and Astrophysics, Academia Sinica
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8.
University of California, Irvine
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9.
Johns Hopkins University
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10.
Johns Hopkins University Applied Physics Laboratory
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11.
Rochester Institute of Technology
Abstract
Copyright and License
© 2026. 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.
Acknowledgement
We acknowledge support from the SPHEREx project under a contract from the NASA/Goddard Space Flight Center to the California Institute of Technology.
Part of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).
This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST.
We acknowledge the use of the Smithsonian High Performance Cluster (SI/HPC), Smithsonian Institution, doi:10.25572/SIHPC. The authors acknowledge the Texas Advanced Computing Center (TACC)21 at The University of Texas at Austin for providing computational resources that have contributed to the research results reported within this paper. J.-E.L. and J.K.N. were supported by National Research Foundation of Korea (NRF) grants funded by the Korea government (MSIT; grant Nos. 2021R1A2C1011718 and RS-2024-00416859).
This research made use of Montage. It is funded by the National Science Foundation under grant No. ACI-1440620, and was previously funded by the National Aeronautics and Space Administration's Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology.
This work made use of Astropy: a community-developed core Python package and an ecosystem of tools and resources for astronomy.
Files
Hora_2026_ApJ_1001_165.pdf
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2603.12390 (arXiv)
Funding
- National Aeronautics and Space Administration
- 80NM0018D0004
- National Aeronautics and Space Administration
- NAS 5-03127
- National Research Foundation of Korea
- 2021R1A2C1011718
- National Research Foundation of Korea
- RS-2024-00416859
- National Science Foundation
- ACI-1440620
- National Aeronautics and Space Administration
- NCC5-626
Dates
- Submitted
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2026-01-16
- Accepted
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2026-03-11
- Available
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2026-04-15Published online
Caltech Custom Metadata
- Caltech groups
- Division of Physics, Mathematics and Astronomy (PMA) , Infrared Processing and Analysis Center (IPAC) , Astronomy Department , Physics Department
- Publication Status
- Published