Silicon, sulfur and iron in the interstellar medium: a high-resolution X-ray spectral study of GX 340+0
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| Autores principales: | , , , , , , , |
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| Formato: | Preprint |
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2026
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| author | Rogantini, Daniele Canizares, Claude Costantini, Elisa Gu, Liyi Mehdipour, Missagh Psaradaki, Ioanna Schulz, Norbert S. Zeegers, Sascha T. |
| author_facet | Rogantini, Daniele Canizares, Claude Costantini, Elisa Gu, Liyi Mehdipour, Missagh Psaradaki, Ioanna Schulz, Norbert S. Zeegers, Sascha T. |
| contents | High-resolution X-ray spectroscopy provides a powerful probe of the interstellar medium (ISM), giving direct access to the composition and physical state of dust grains and atomic species in dense environments. We present a study of the gas and dust along the line of sight to the bright low-mass X-ray binary GX 340+0, which samples higher-density gases in the ISM. Using deep Chandra/HETG spectra, we characterize X-ray absorption fine structure from dust, gas absorption lines, and the optical depths of the Si, S, and Fe K-edges. By fitting these three edges simultaneously, we reduce degeneracies in the dust composition and find that amorphous olivine dominates the fractional contribution among the dust columns ($\sim$65%), followed by metallic iron ($\sim$19%), iron sulfides (pyrrhotite and troilite; $\sim$10%), and fayalite ($\sim$5%), with the remaining species contributing only a few percent in total. From the inferred stoichiometry, we estimate that $\sim$74% of Fe is associated with silicates, $\sim$8% with sulfides, and $\sim$18% with metallic iron, suggesting that Fe is predominantly incorporated in iron rich silicate grains along this sightline. We detect S ii absorption and infer a sulfur dust fraction of $\sim$35%. We also detect absorption structure near the Ca and Ar K edges, highlighting the need for improved atomic photoabsorption data. The Chandra/HETG spectral resolution remains essential to disentangle dust and gas contributions at the Si and S K edges, providing a benchmark for dust characterization in high-density regions in the ISM. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_03375 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Silicon, sulfur and iron in the interstellar medium: a high-resolution X-ray spectral study of GX 340+0 Rogantini, Daniele Canizares, Claude Costantini, Elisa Gu, Liyi Mehdipour, Missagh Psaradaki, Ioanna Schulz, Norbert S. Zeegers, Sascha T. Astrophysics of Galaxies High Energy Astrophysical Phenomena High-resolution X-ray spectroscopy provides a powerful probe of the interstellar medium (ISM), giving direct access to the composition and physical state of dust grains and atomic species in dense environments. We present a study of the gas and dust along the line of sight to the bright low-mass X-ray binary GX 340+0, which samples higher-density gases in the ISM. Using deep Chandra/HETG spectra, we characterize X-ray absorption fine structure from dust, gas absorption lines, and the optical depths of the Si, S, and Fe K-edges. By fitting these three edges simultaneously, we reduce degeneracies in the dust composition and find that amorphous olivine dominates the fractional contribution among the dust columns ($\sim$65%), followed by metallic iron ($\sim$19%), iron sulfides (pyrrhotite and troilite; $\sim$10%), and fayalite ($\sim$5%), with the remaining species contributing only a few percent in total. From the inferred stoichiometry, we estimate that $\sim$74% of Fe is associated with silicates, $\sim$8% with sulfides, and $\sim$18% with metallic iron, suggesting that Fe is predominantly incorporated in iron rich silicate grains along this sightline. We detect S ii absorption and infer a sulfur dust fraction of $\sim$35%. We also detect absorption structure near the Ca and Ar K edges, highlighting the need for improved atomic photoabsorption data. The Chandra/HETG spectral resolution remains essential to disentangle dust and gas contributions at the Si and S K edges, providing a benchmark for dust characterization in high-density regions in the ISM. |
| title | Silicon, sulfur and iron in the interstellar medium: a high-resolution X-ray spectral study of GX 340+0 |
| topic | Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2604.03375 |