The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps
High-precision exoplanet eclipse light curves, like those possible with JWST, enable flux and temperature mapping of exoplanet atmospheres. These eclipse maps will have unprecedented precision, providing an opportunity to constrain current theoretical predictions of exoplanet atmospheres. However, e...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astronomical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-3881/acf862 |
| _version_ | 1797671729412177920 |
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| author | Ryan C. Challener Emily Rauscher |
| author_facet | Ryan C. Challener Emily Rauscher |
| author_sort | Ryan C. Challener |
| collection | DOAJ |
| description | High-precision exoplanet eclipse light curves, like those possible with JWST, enable flux and temperature mapping of exoplanet atmospheres. These eclipse maps will have unprecedented precision, providing an opportunity to constrain current theoretical predictions of exoplanet atmospheres. However, eclipse mapping has unavoidable mathematical limitations because many map patterns are unobservable. This “null space” has implications for making comparisons between predictions from general circulation models (GCMs) and the observed planet maps and thus affects our understanding of the physical processes driving the observed maps. We describe the eclipse-mapping null space and show how GCM forward models can be transformed to their observable modes for more appropriate comparison with retrieved eclipse maps, demonstrated with applications to synthetic data of an ultrahot Jupiter and a cloudy warm Jupiter under JWST best-case and extreme-precision observing scenarios. We show that the effects of the null space can be mitigated and manipulated through observational design, and JWST exposure times are short enough to not increase the size of the null space. Furthermore, we show the mathematical connection between the null space and the “eigenmapping” method, demonstrating how eigenmaps can be used to understand the null space in a model-independent way. We leverage this connection to incorporate null-space uncertainties in retrieved maps, which increases the uncertainties to encompass the ground truth for synthetic data. The comparisons between observed maps and forward models that are enabled by this work, and the improved eclipse-mapping uncertainties, will be critical to our interpretation of multidimensional aspects of exoplanets in the JWST era. |
| first_indexed | 2024-03-11T21:19:46Z |
| format | Article |
| id | doaj.art-3c54d3d9704f4b719f6269a9d354d754 |
| institution | Directory Open Access Journal |
| issn | 1538-3881 |
| language | English |
| last_indexed | 2024-03-11T21:19:46Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj.art-3c54d3d9704f4b719f6269a9d354d7542023-09-28T09:09:28ZengIOP PublishingThe Astronomical Journal1538-38812023-01-01166417610.3847/1538-3881/acf862The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed MapsRyan C. Challener0https://orcid.org/0000-0002-8211-6538Emily Rauscher1https://orcid.org/0000-0003-3963-9672Department of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109, USADepartment of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109, USAHigh-precision exoplanet eclipse light curves, like those possible with JWST, enable flux and temperature mapping of exoplanet atmospheres. These eclipse maps will have unprecedented precision, providing an opportunity to constrain current theoretical predictions of exoplanet atmospheres. However, eclipse mapping has unavoidable mathematical limitations because many map patterns are unobservable. This “null space” has implications for making comparisons between predictions from general circulation models (GCMs) and the observed planet maps and thus affects our understanding of the physical processes driving the observed maps. We describe the eclipse-mapping null space and show how GCM forward models can be transformed to their observable modes for more appropriate comparison with retrieved eclipse maps, demonstrated with applications to synthetic data of an ultrahot Jupiter and a cloudy warm Jupiter under JWST best-case and extreme-precision observing scenarios. We show that the effects of the null space can be mitigated and manipulated through observational design, and JWST exposure times are short enough to not increase the size of the null space. Furthermore, we show the mathematical connection between the null space and the “eigenmapping” method, demonstrating how eigenmaps can be used to understand the null space in a model-independent way. We leverage this connection to incorporate null-space uncertainties in retrieved maps, which increases the uncertainties to encompass the ground truth for synthetic data. The comparisons between observed maps and forward models that are enabled by this work, and the improved eclipse-mapping uncertainties, will be critical to our interpretation of multidimensional aspects of exoplanets in the JWST era.https://doi.org/10.3847/1538-3881/acf862Exoplanet atmospheresExoplanetsEclipses |
| spellingShingle | Ryan C. Challener Emily Rauscher The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps The Astronomical Journal Exoplanet atmospheres Exoplanets Eclipses |
| title | The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps |
| title_full | The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps |
| title_fullStr | The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps |
| title_full_unstemmed | The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps |
| title_short | The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps |
| title_sort | eclipse mapping null space comparing theoretical predictions with observed maps |
| topic | Exoplanet atmospheres Exoplanets Eclipses |
| url | https://doi.org/10.3847/1538-3881/acf862 |
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