Mapping water ice with infrared broadband photometry
Fuente:
arXiv
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| Natura: | Preprint |
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2025
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| _version_ | 1866909845683175424 |
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| author | Meingast, Stefan |
| author_facet | Meingast, Stefan |
| contents | Interstellar ices play a fundamental role in the physical and chemical evolution of molecular clouds and star-forming regions, yet their large-scale distribution and abundance remain challenging to map. In this work, I present the ice color excess method, which parametrizes the peak optical depth ($τ_{3.0}^{\mathrm{max}}$) of the prominent 3$μ$m absorption feature, which is predominantly caused by the presence of solid H$_2$O. The method builds on well-established near-infrared color excess techniques and uses widely available infrared broadband photometry. Through detailed evaluation of passband combinations and a comprehensive error analysis, I construct the ice color excess metric $Λ(W_1 - I_1)$. This parameter emerges as the optimal choice that minimizes systematic errors while leveraging high-quality, widely available photometry from Spitzer and WISE data archives. To calibrate the method, I compile from the literature a sample of stars located in the background of nearby molecular clouds, for which spectroscopically measured optical depths are available. The empirical calibration yields a remarkably tight correlation between $τ_{3.0}^{\mathrm{max}}$ and $Λ(W_1 - I_1)$. This photometric technique opens a new avenue for tracing the icy component of the interstellar medium on Galactic scales, providing a powerful complement to spectroscopic surveys and enabling new insights into the environmental dependence of the formation and evolution of icy dust grains. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_18688 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Mapping water ice with infrared broadband photometry Meingast, Stefan Astrophysics of Galaxies Interstellar ices play a fundamental role in the physical and chemical evolution of molecular clouds and star-forming regions, yet their large-scale distribution and abundance remain challenging to map. In this work, I present the ice color excess method, which parametrizes the peak optical depth ($τ_{3.0}^{\mathrm{max}}$) of the prominent 3$μ$m absorption feature, which is predominantly caused by the presence of solid H$_2$O. The method builds on well-established near-infrared color excess techniques and uses widely available infrared broadband photometry. Through detailed evaluation of passband combinations and a comprehensive error analysis, I construct the ice color excess metric $Λ(W_1 - I_1)$. This parameter emerges as the optimal choice that minimizes systematic errors while leveraging high-quality, widely available photometry from Spitzer and WISE data archives. To calibrate the method, I compile from the literature a sample of stars located in the background of nearby molecular clouds, for which spectroscopically measured optical depths are available. The empirical calibration yields a remarkably tight correlation between $τ_{3.0}^{\mathrm{max}}$ and $Λ(W_1 - I_1)$. This photometric technique opens a new avenue for tracing the icy component of the interstellar medium on Galactic scales, providing a powerful complement to spectroscopic surveys and enabling new insights into the environmental dependence of the formation and evolution of icy dust grains. |
| title | Mapping water ice with infrared broadband photometry |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2507.18688 |