Jialu Li, Adwin Boogert, Alexander G. G. M. Tielens
{"title":"关于 JWST/MIRI 观测到的气相 H2O 中红外吸收线的解释","authors":"Jialu Li, Adwin Boogert, Alexander G. G. M. Tielens","doi":"10.3847/1538-4365/ad571a","DOIUrl":null,"url":null,"abstract":"Rovibrational absorption lines of H<sub>2</sub>O in the 5–8 <italic toggle=\"yes\">μ</italic>m wavelength range selectively probe gas against the mid-infrared continuum-emitting background of the inner regions of young stellar objects and active galactic nuclei and deliver important information about these warm, dust-obscured environments. JWST/Mid-Infrared Instrument (MIRI) detects these lines in many lines of sight at a moderate spectral resolving power of <italic toggle=\"yes\">R</italic> ∼ 3500 (full width at half-maximum of 85 km s<sup>−1</sup>). Based on our analysis of high-resolution SOFIA/EXES observations, we find that the interpretation of JWST/MIRI absorption spectra can be severely hampered by the blending of individual transitions and the lost information on the intrinsic line width or the partial coverage of the background continuum source. In this paper, we point out problems such as degeneracy that arise in deriving physical properties from an insufficiently resolved spectrum. This can lead to differences in the column density by 2 orders of magnitude. We emphasize the importance of weighting optically thin and weak lines in spectral analyses and provide recipes for breaking down the coupled parameters. We also provide an online tool to generate the H<sub>2</sub>O absorption line spectra that can be compared to observations.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On the Interpretation of Mid-infrared Absorption Lines of Gas-phase H2O as Observed by JWST/MIRI\",\"authors\":\"Jialu Li, Adwin Boogert, Alexander G. G. M. Tielens\",\"doi\":\"10.3847/1538-4365/ad571a\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Rovibrational absorption lines of H<sub>2</sub>O in the 5–8 <italic toggle=\\\"yes\\\">μ</italic>m wavelength range selectively probe gas against the mid-infrared continuum-emitting background of the inner regions of young stellar objects and active galactic nuclei and deliver important information about these warm, dust-obscured environments. JWST/Mid-Infrared Instrument (MIRI) detects these lines in many lines of sight at a moderate spectral resolving power of <italic toggle=\\\"yes\\\">R</italic> ∼ 3500 (full width at half-maximum of 85 km s<sup>−1</sup>). Based on our analysis of high-resolution SOFIA/EXES observations, we find that the interpretation of JWST/MIRI absorption spectra can be severely hampered by the blending of individual transitions and the lost information on the intrinsic line width or the partial coverage of the background continuum source. In this paper, we point out problems such as degeneracy that arise in deriving physical properties from an insufficiently resolved spectrum. This can lead to differences in the column density by 2 orders of magnitude. We emphasize the importance of weighting optically thin and weak lines in spectral analyses and provide recipes for breaking down the coupled parameters. We also provide an online tool to generate the H<sub>2</sub>O absorption line spectra that can be compared to observations.\",\"PeriodicalId\":22368,\"journal\":{\"name\":\"The Astrophysical Journal Supplement Series\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-07-31\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Astrophysical Journal Supplement Series\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.3847/1538-4365/ad571a\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Astrophysical Journal Supplement Series","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/1538-4365/ad571a","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
On the Interpretation of Mid-infrared Absorption Lines of Gas-phase H2O as Observed by JWST/MIRI
Rovibrational absorption lines of H2O in the 5–8 μm wavelength range selectively probe gas against the mid-infrared continuum-emitting background of the inner regions of young stellar objects and active galactic nuclei and deliver important information about these warm, dust-obscured environments. JWST/Mid-Infrared Instrument (MIRI) detects these lines in many lines of sight at a moderate spectral resolving power of R ∼ 3500 (full width at half-maximum of 85 km s−1). Based on our analysis of high-resolution SOFIA/EXES observations, we find that the interpretation of JWST/MIRI absorption spectra can be severely hampered by the blending of individual transitions and the lost information on the intrinsic line width or the partial coverage of the background continuum source. In this paper, we point out problems such as degeneracy that arise in deriving physical properties from an insufficiently resolved spectrum. This can lead to differences in the column density by 2 orders of magnitude. We emphasize the importance of weighting optically thin and weak lines in spectral analyses and provide recipes for breaking down the coupled parameters. We also provide an online tool to generate the H2O absorption line spectra that can be compared to observations.