The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers
Low-ionization broad absorption line QSOs (LoBALs) are suspected to be merging systems in which extreme, active galactic nucleus-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of Lo...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acc6d0 |
| _version_ | 1797696132446420992 |
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| author | Mariana S. Lazarova Gabriela Canalizo Mark Lacy Wyatt Behn Kaitlyn Raub Vardha N. Bennert Duncan Farrah |
| author_facet | Mariana S. Lazarova Gabriela Canalizo Mark Lacy Wyatt Behn Kaitlyn Raub Vardha N. Bennert Duncan Farrah |
| author_sort | Mariana S. Lazarova |
| collection | DOAJ |
| description | Low-ionization broad absorption line QSOs (LoBALs) are suspected to be merging systems in which extreme, active galactic nucleus-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of LoBALs, we present the first high-resolution morphological analysis of a volume-limited sample of 22 Sloan Digital Sky Survey (SDSS)-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field Camera 3 observations. Host galaxies are resolved in 86% of the systems in F125W, which is sensitive to old stellar populations, while only 18% are detected in F475W, which traces young, unobscured stellar populations. Signs of recent or ongoing tidal interaction are present in 45%–64% of the hosts, including double nuclei, tidal tails, bridges, plumes, shells, and extended debris. Ongoing interaction with a companion is apparent in 27%−41% of the LoBALs, with as much as 1/3 of the sample representing late-stage mergers at projected nuclear separations <10 kpc. Detailed surface brightness modeling indicates that 41% of the hosts are bulge dominated while only 18% are disks. We discuss trends in various properties as a function of merger stage and parametric morphology. Notably, mergers are associated with slower, dustier winds than those seen in undisturbed/unresolved hosts. Our results favor an evolutionary scenario in which quasar-level accretion during various merger stages is associated with the observed outflows in low- z LoBALs. We discuss differences between LoBALs and FeLoBALs and show that selection via the traditional balnicity index would have excluded all but one of the mergers. |
| first_indexed | 2024-03-12T03:21:52Z |
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| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:21:52Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj.art-807f7225486a40da87792f4166d23cf42023-09-03T13:56:00ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194926910.3847/1538-4357/acc6d0The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by MergersMariana S. Lazarova0https://orcid.org/0000-0003-3818-6691Gabriela Canalizo1https://orcid.org/0000-0003-4693-6157Mark Lacy2https://orcid.org/0000-0002-3032-1783Wyatt Behn3Kaitlyn Raub4Vardha N. Bennert5https://orcid.org/0000-0003-2064-0518Duncan Farrah6https://orcid.org/0000-0003-1748-2010Department of Physics and Astronomy, University of Northern Colorado , Greeley, CO 80639, USA ; mariana.lazarova@unco.eduDepartment of Physics and Astronomy, University of California , Riverside, CA 92521, USANational ALMA Science Center , National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USADepartment of Physics, University of Wisconsin-Madison , Madison, WI 53706, USA; previously at Department of Physics and Astronomy, University of Nebraska-Kearney , Kearney, NE 68849, USADepartment of Physics and Astronomy, University of Northern Colorado , Greeley, CO 80639, USA ; mariana.lazarova@unco.eduPhysics Department California Polytechnic State University , 1 Grand Avenue, San Luis Obispo, CA 93407, USADepartment of Physics and Astronomy, University of Hawai’i at Mãnoa , 2505 Correa Road, Honolulu, HI 96822, USALow-ionization broad absorption line QSOs (LoBALs) are suspected to be merging systems in which extreme, active galactic nucleus-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of LoBALs, we present the first high-resolution morphological analysis of a volume-limited sample of 22 Sloan Digital Sky Survey (SDSS)-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field Camera 3 observations. Host galaxies are resolved in 86% of the systems in F125W, which is sensitive to old stellar populations, while only 18% are detected in F475W, which traces young, unobscured stellar populations. Signs of recent or ongoing tidal interaction are present in 45%–64% of the hosts, including double nuclei, tidal tails, bridges, plumes, shells, and extended debris. Ongoing interaction with a companion is apparent in 27%−41% of the LoBALs, with as much as 1/3 of the sample representing late-stage mergers at projected nuclear separations <10 kpc. Detailed surface brightness modeling indicates that 41% of the hosts are bulge dominated while only 18% are disks. We discuss trends in various properties as a function of merger stage and parametric morphology. Notably, mergers are associated with slower, dustier winds than those seen in undisturbed/unresolved hosts. Our results favor an evolutionary scenario in which quasar-level accretion during various merger stages is associated with the observed outflows in low- z LoBALs. We discuss differences between LoBALs and FeLoBALs and show that selection via the traditional balnicity index would have excluded all but one of the mergers.https://doi.org/10.3847/1538-4357/acc6d0Active galaxiesInteracting galaxiesGalaxy evolutionQuasarsBroad-absorption line quasar |
| spellingShingle | Mariana S. Lazarova Gabriela Canalizo Mark Lacy Wyatt Behn Kaitlyn Raub Vardha N. Bennert Duncan Farrah The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers The Astrophysical Journal Active galaxies Interacting galaxies Galaxy evolution Quasars Broad-absorption line quasar |
| title | The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers |
| title_full | The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers |
| title_fullStr | The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers |
| title_full_unstemmed | The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers |
| title_short | The Nature of LoBAL QSOs. II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers |
| title_sort | nature of lobal qsos ii hst wfc3 observations reveal host galaxies dominated by mergers |
| topic | Active galaxies Interacting galaxies Galaxy evolution Quasars Broad-absorption line quasar |
| url | https://doi.org/10.3847/1538-4357/acc6d0 |
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