Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface
Metals in the diffuse, ionized gas at the boundary between the Milky Way’s interstellar medium (ISM) and circumgalactic medium, known as the disk–halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region ar...
Saved in:
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad84f8 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850129149003300864 |
|---|---|
| author | Bo-Eun Choi Jessica K. Werk Kirill Tchernyshyov J. Xavier Prochaska Yong Zheng Mary E. Putman Drummond B. Fielding Jay Strader |
| author_facet | Bo-Eun Choi Jessica K. Werk Kirill Tchernyshyov J. Xavier Prochaska Yong Zheng Mary E. Putman Drummond B. Fielding Jay Strader |
| author_sort | Bo-Eun Choi |
| collection | DOAJ |
| description | Metals in the diffuse, ionized gas at the boundary between the Milky Way’s interstellar medium (ISM) and circumgalactic medium, known as the disk–halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region are challenging due to obscuration by the Milky Way ISM and uncertain ionization corrections that affect the total hydrogen column density. In this work, we constrain ionization corrections to neutral hydrogen column densities using precisely measured electron column densities from the dispersion measures of pulsars that lie in the same globular clusters as UV-bright targets with high-resolution absorption spectroscopy. We address the blending of absorption lines with the ISM by jointly fitting Voigt profiles to all absorption components. We present our metallicity estimates for the DHI of the Milky Way based on detailed photoionization modeling of the absorption from ionized metal lines and ionization-corrected total hydrogen columns. Generally, the gas clouds show a large scatter in metallicity, ranging between 0.04 and 3.2 Z _⊙ , implying that the DHI consists of a mixture of gaseous structures having multiple origins. We estimate the inflow and outflow timescales of the DHI ionized clouds to be 6–35 Myr. We report the detection of an infalling cloud with supersolar metallicity that suggests a Galactic fountain mechanism, whereas at least one low-metallicity outflowing cloud ( Z < 0.1 Z _⊙ ) poses a challenge for Galactic fountain and feedback models. |
| format | Article |
| id | doaj-art-8a76570732b04a21bc5d16cdff42d3ad |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-8a76570732b04a21bc5d16cdff42d3ad2025-08-20T02:33:05ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01976222210.3847/1538-4357/ad84f8Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo InterfaceBo-Eun Choi0https://orcid.org/0000-0002-9040-672XJessica K. Werk1https://orcid.org/0000-0002-0355-0134Kirill Tchernyshyov2https://orcid.org/0000-0003-0789-9939J. Xavier Prochaska3https://orcid.org/0000-0002-7738-6875Yong Zheng4https://orcid.org/0000-0003-4158-5116Mary E. Putman5https://orcid.org/0000-0002-1129-1873Drummond B. Fielding6https://orcid.org/0000-0003-3806-8548Jay Strader7https://orcid.org/0000-0002-1468-9668Department of Astronomy, University of Washington , Seattle, WA 98195, USADepartment of Astronomy, University of Washington , Seattle, WA 98195, USADepartment of Astronomy, University of Washington , Seattle, WA 98195, USADepartment of Astronomy and Astrophysics, University of California , Santa Cruz, CA 95064, USA; Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) , 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan; Division of Science, National Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanDepartment of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute , Troy, NY 12180, USADepartment of Astronomy, Columbia University , New York, NY 10027, USADepartment of Astronomy, Cornell University , Ithaca, NY 14853, USA; Center for Computational Astrophysics, Flatiron Institute , 162 Fifth Avenue, New York, NY 10010, USACenter for Data Intensive and Time Domain Astronomy, Department of Physics and Astronomy, Michigan State University , East Lansing, MI 48824, USAMetals in the diffuse, ionized gas at the boundary between the Milky Way’s interstellar medium (ISM) and circumgalactic medium, known as the disk–halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region are challenging due to obscuration by the Milky Way ISM and uncertain ionization corrections that affect the total hydrogen column density. In this work, we constrain ionization corrections to neutral hydrogen column densities using precisely measured electron column densities from the dispersion measures of pulsars that lie in the same globular clusters as UV-bright targets with high-resolution absorption spectroscopy. We address the blending of absorption lines with the ISM by jointly fitting Voigt profiles to all absorption components. We present our metallicity estimates for the DHI of the Milky Way based on detailed photoionization modeling of the absorption from ionized metal lines and ionization-corrected total hydrogen columns. Generally, the gas clouds show a large scatter in metallicity, ranging between 0.04 and 3.2 Z _⊙ , implying that the DHI consists of a mixture of gaseous structures having multiple origins. We estimate the inflow and outflow timescales of the DHI ionized clouds to be 6–35 Myr. We report the detection of an infalling cloud with supersolar metallicity that suggests a Galactic fountain mechanism, whereas at least one low-metallicity outflowing cloud ( Z < 0.1 Z _⊙ ) poses a challenge for Galactic fountain and feedback models.https://doi.org/10.3847/1538-4357/ad84f8Circumgalactic mediumMilky Way GalaxyMilky Way Galaxy fountainsGalaxy fountainsUltraviolet spectroscopy |
| spellingShingle | Bo-Eun Choi Jessica K. Werk Kirill Tchernyshyov J. Xavier Prochaska Yong Zheng Mary E. Putman Drummond B. Fielding Jay Strader Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface The Astrophysical Journal Circumgalactic medium Milky Way Galaxy Milky Way Galaxy fountains Galaxy fountains Ultraviolet spectroscopy |
| title | Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface |
| title_full | Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface |
| title_fullStr | Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface |
| title_full_unstemmed | Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface |
| title_short | Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface |
| title_sort | metallicity mapping of the ionized diffuse gas at the milky way disk halo interface |
| topic | Circumgalactic medium Milky Way Galaxy Milky Way Galaxy fountains Galaxy fountains Ultraviolet spectroscopy |
| url | https://doi.org/10.3847/1538-4357/ad84f8 |
| work_keys_str_mv | AT boeunchoi metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT jessicakwerk metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT kirilltchernyshyov metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT jxavierprochaska metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT yongzheng metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT maryeputman metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT drummondbfielding metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface AT jaystrader metallicitymappingoftheionizeddiffusegasatthemilkywaydiskhalointerface |