Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines
Galactic outflows provide important feedback effects to regulate the evolution of host galaxies. Two primary diagnostics of outflows are broad and/or blueshifted emission and absorption lines. Even though well-established methods exist to analyze these outflow signatures, connections between them ar...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/adc302 |
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| author | Xinfeng Xu Alaina Henry Timothy Heckman Cody Carr Allison L. Strom Tucker Jones Danielle A. Berg John Chisholm Dawn Erb Bethan L. James Anne Jaskot Crystal L. Martin Matilde Mingozzi Peter Senchyna Namrata Roy Claudia Scarlata Daniel P. Stark |
| author_facet | Xinfeng Xu Alaina Henry Timothy Heckman Cody Carr Allison L. Strom Tucker Jones Danielle A. Berg John Chisholm Dawn Erb Bethan L. James Anne Jaskot Crystal L. Martin Matilde Mingozzi Peter Senchyna Namrata Roy Claudia Scarlata Daniel P. Stark |
| author_sort | Xinfeng Xu |
| collection | DOAJ |
| description | Galactic outflows provide important feedback effects to regulate the evolution of host galaxies. Two primary diagnostics of outflows are broad and/or blueshifted emission and absorption lines. Even though well-established methods exist to analyze these outflow signatures, connections between them are rarely studied and largely unknown. In this paper, we conduct such a study in a sample of 33 low-redshift starburst galaxies. Their UV absorption lines are detected by the Hubble Space Telescope, and optical emission lines are observed by Keck or the Very Large Telescope. We find that the outflow properties derived from emission and absorption lines are tightly correlated. These include outflow maximum velocity, line width, and radial extent. On average, in the same galaxy, the maximum velocity and line width of outflows measured from emission lines reach only 60%–70% of those from the absorption lines. We also find outflow rates derived from emission lines are consistently lower than those from absorption lines by 0.2–0.5 dex. These findings can be explained by a radial decline in density and a corresponding increase in outflow velocity, combined with the fact that emission line luminosity scales with the square of the density while absorption line depth scales linearly. We test both spherical and biconical outflow models and find that the same radial outflow velocity and density distributions can explain the observed correlations. These results provide novel calibration between galactic outflow properties measured from the two diagnostics and underscore the need for high-fidelity UV and optical spectra to accurately assess galactic feedback effects in high- z galaxies. |
| format | Article |
| id | doaj-art-25324445274a4c82a8153100e5d94eac |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-25324445274a4c82a8153100e5d94eac2025-08-20T02:20:11ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198419410.3847/1538-4357/adc302Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission LinesXinfeng Xu0https://orcid.org/0000-0002-9217-7051Alaina Henry1https://orcid.org/0000-0002-6586-4446Timothy Heckman2https://orcid.org/0000-0001-6670-6370Cody Carr3https://orcid.org/0000-0003-4166-2855Allison L. Strom4https://orcid.org/0000-0001-6369-1636Tucker Jones5https://orcid.org/0000-0001-5860-3419Danielle A. Berg6https://orcid.org/0000-0002-4153-053XJohn Chisholm7https://orcid.org/0000-0002-0302-2577Dawn Erb8https://orcid.org/0000-0001-9714-2758Bethan L. James9https://orcid.org/0000-0003-4372-2006Anne Jaskot10https://orcid.org/0000-0002-6790-5125Crystal L. Martin11https://orcid.org/0000-0001-9189-7818Matilde Mingozzi12https://orcid.org/0000-0003-2589-762XPeter Senchyna13https://orcid.org/0000-0002-9132-6561Namrata Roy14https://orcid.org/0000-0002-4430-8846Claudia Scarlata15https://orcid.org/0000-0002-9136-8876Daniel P. Stark16https://orcid.org/0000-0001-6106-5172Department of Physics and Astronomy, Northwestern University , 2145 Sheridan Road, Evanston, IL 60208, USA ; xinfeng.xu@northwestern.edu; Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) , 1800 Sherman Avenue, Evanston, IL 60201, USACenter for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USACenter for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA; School of Earth and Space Exploration, Arizona State University , Tempe, AZ 85287, USACenter for Cosmology and Computational Astrophysics, Institute for Advanced Study in Physics, Zhejiang University , Hangzhou 310058, People’s Republic of China; Institute of Astronomy, School of Physics, Zhejiang University , Hangzhou 310058, People’s Republic of ChinaDepartment of Physics and Astronomy, Northwestern University , 2145 Sheridan Road, Evanston, IL 60208, USA ; xinfeng.xu@northwestern.edu; Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) , 1800 Sherman Avenue, Evanston, IL 60201, USADepartment of Physics and Astronomy, University of California Davis , 1 Shields Avenue, Davis, CA 95616, USADepartment of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USADepartment of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USAThe Leonard E. Parker Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee , 3135 N Maryland Avenue, Milwaukee, WI 53211, USAAURA for ESA, Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USADepartment of Astronomy, Williams College , Williamstown, MA 01267, USADepartment of Physics, University of California Santa Barbara , Santa Barbara, CA 93106, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USAThe Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USACenter for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USAMinnesota Institute for Astrophysics, University of Minnesota , 116 Church Street SE, Minneapolis, MN 55455, USAUniversity of California, Berkeley , Department of Astronomy, 501 Campbell Hall, Berkeley, CA 94720, USAGalactic outflows provide important feedback effects to regulate the evolution of host galaxies. Two primary diagnostics of outflows are broad and/or blueshifted emission and absorption lines. Even though well-established methods exist to analyze these outflow signatures, connections between them are rarely studied and largely unknown. In this paper, we conduct such a study in a sample of 33 low-redshift starburst galaxies. Their UV absorption lines are detected by the Hubble Space Telescope, and optical emission lines are observed by Keck or the Very Large Telescope. We find that the outflow properties derived from emission and absorption lines are tightly correlated. These include outflow maximum velocity, line width, and radial extent. On average, in the same galaxy, the maximum velocity and line width of outflows measured from emission lines reach only 60%–70% of those from the absorption lines. We also find outflow rates derived from emission lines are consistently lower than those from absorption lines by 0.2–0.5 dex. These findings can be explained by a radial decline in density and a corresponding increase in outflow velocity, combined with the fact that emission line luminosity scales with the square of the density while absorption line depth scales linearly. We test both spherical and biconical outflow models and find that the same radial outflow velocity and density distributions can explain the observed correlations. These results provide novel calibration between galactic outflow properties measured from the two diagnostics and underscore the need for high-fidelity UV and optical spectra to accurately assess galactic feedback effects in high- z galaxies.https://doi.org/10.3847/1538-4357/adc302Galaxy evolutionGalactic windsGalaxy kinematicsStarburst galaxiesGalaxy spectroscopyUltraviolet spectroscopy |
| spellingShingle | Xinfeng Xu Alaina Henry Timothy Heckman Cody Carr Allison L. Strom Tucker Jones Danielle A. Berg John Chisholm Dawn Erb Bethan L. James Anne Jaskot Crystal L. Martin Matilde Mingozzi Peter Senchyna Namrata Roy Claudia Scarlata Daniel P. Stark Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines The Astrophysical Journal Galaxy evolution Galactic winds Galaxy kinematics Starburst galaxies Galaxy spectroscopy Ultraviolet spectroscopy |
| title | Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines |
| title_full | Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines |
| title_fullStr | Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines |
| title_full_unstemmed | Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines |
| title_short | Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines |
| title_sort | shining a light on the connections between galactic outflows seen in absorption and emission lines |
| topic | Galaxy evolution Galactic winds Galaxy kinematics Starburst galaxies Galaxy spectroscopy Ultraviolet spectroscopy |
| url | https://doi.org/10.3847/1538-4357/adc302 |
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