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| Formato: | Preprint |
| Publicado: |
2025
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| Acceso en línea: | https://arxiv.org/abs/2504.15641 |
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| _version_ | 1866915253278736384 |
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| author | Luan, Luan Wang, Q. Daniel |
| author_facet | Luan, Luan Wang, Q. Daniel |
| contents | X-ray observations can be used to effectively probe the galactic ecosystem, particularly its hot and energetic components. However, existing X-ray studies of nearby star-forming galaxies are limited by insufficient data statistics and a lack of suitable spectral modeling to account for X-ray emission and absorption geometry. We present results from an X-ray spectral study of M51 using 1.3-Ms Chandra data, the most extensive for such a galaxy. This allows the extraction of diffuse X-ray emission spectra from spiral arm phase-dependent regions using a logarithmic spiral coordinate system. A hierarchical Bayesian approach analyzes these spectra, testing models from simple 1-T hot plasma to those including distributed hot plasma and X-ray-absorbing cool gas. We recommend a model fitting the spectra well, featuring a galactic corona with a lognormal temperature distribution and a disk with mixed X-ray emissions and absorption. In this model, only half of the coronal emission is subject to internal absorption. The best-fit absorbing gas column density is roughly twice that inferred from optical extinction of stellar light. The temperature distribution shows a mean temperature of $\sim 0.1$ keV and an average one-dex dispersion that is enhanced on the spiral arms. The corona's radiative cooling might balance the mechanical energy input from stellar feedback. These results highlight the effectiveness of X-ray mapping of the corona and cool gas in spiral galaxies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_15641 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Diffuse X-ray emission in M51: a hierarchical Bayesian spatially-resolved spectral analysis Luan, Luan Wang, Q. Daniel High Energy Astrophysical Phenomena Astrophysics of Galaxies X-ray observations can be used to effectively probe the galactic ecosystem, particularly its hot and energetic components. However, existing X-ray studies of nearby star-forming galaxies are limited by insufficient data statistics and a lack of suitable spectral modeling to account for X-ray emission and absorption geometry. We present results from an X-ray spectral study of M51 using 1.3-Ms Chandra data, the most extensive for such a galaxy. This allows the extraction of diffuse X-ray emission spectra from spiral arm phase-dependent regions using a logarithmic spiral coordinate system. A hierarchical Bayesian approach analyzes these spectra, testing models from simple 1-T hot plasma to those including distributed hot plasma and X-ray-absorbing cool gas. We recommend a model fitting the spectra well, featuring a galactic corona with a lognormal temperature distribution and a disk with mixed X-ray emissions and absorption. In this model, only half of the coronal emission is subject to internal absorption. The best-fit absorbing gas column density is roughly twice that inferred from optical extinction of stellar light. The temperature distribution shows a mean temperature of $\sim 0.1$ keV and an average one-dex dispersion that is enhanced on the spiral arms. The corona's radiative cooling might balance the mechanical energy input from stellar feedback. These results highlight the effectiveness of X-ray mapping of the corona and cool gas in spiral galaxies. |
| title | Diffuse X-ray emission in M51: a hierarchical Bayesian spatially-resolved spectral analysis |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2504.15641 |