Decoding the Single-peaked HI Spectra of Low Redshift Post-starburst Galaxies
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arXiv
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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866909755099840512 |
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| author | Huang, Qifeng Wang, Jing Ellison, Sara L. Liang, Zezhong Lin, Xuchen Yang, Dong |
| author_facet | Huang, Qifeng Wang, Jing Ellison, Sara L. Liang, Zezhong Lin, Xuchen Yang, Dong |
| contents | Recent observations with the Five-hundred-meter Aperture Spherical Telescope (FAST) have revealed abundant reservoirs of neutral hydrogen (HI) in low redshift post-starburst galaxies (PSBs), raising the question of why star formation ceases rapidly in these systems. In this study, we present a detailed analysis of the shape of the integrated HI spectra of 67 PSBs. We find that PSBs exhibit significantly higher HI spectral concentration values ($K$) compared to a matched sample from xGASS, and are more comparable to those of starburst galaxies. By extending our analysis to spatially resolved HI data from THINGS and ATLAS$^{\rm 3D}$, we show that both centrally concentrated HI distributions and dynamically unsettled HI can effectively increase $K$, while non-axisymmetric structures only contribute to the scatter of the $K$ distribution. Distinguishing between central concentration and dynamically unsettled gas as the origin of high $K$ can be achieved by measuring the spectral asymmetry ($A_{\rm F}$), making the $K$-$A_{\rm F}$ plane a powerful diagnostic tool for identifying galaxies with unsettled HI using integrated spectra alone. Based on their location in the $K$-$A_{\rm F}$ plane, we find that most PSBs are not dominated by unsettled HI, but rather exhibit elevated central gas concentration. Both modes of gas redistribution in PSBs may eventually contribute to their quenching. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_19545 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Decoding the Single-peaked HI Spectra of Low Redshift Post-starburst Galaxies Huang, Qifeng Wang, Jing Ellison, Sara L. Liang, Zezhong Lin, Xuchen Yang, Dong Astrophysics of Galaxies Recent observations with the Five-hundred-meter Aperture Spherical Telescope (FAST) have revealed abundant reservoirs of neutral hydrogen (HI) in low redshift post-starburst galaxies (PSBs), raising the question of why star formation ceases rapidly in these systems. In this study, we present a detailed analysis of the shape of the integrated HI spectra of 67 PSBs. We find that PSBs exhibit significantly higher HI spectral concentration values ($K$) compared to a matched sample from xGASS, and are more comparable to those of starburst galaxies. By extending our analysis to spatially resolved HI data from THINGS and ATLAS$^{\rm 3D}$, we show that both centrally concentrated HI distributions and dynamically unsettled HI can effectively increase $K$, while non-axisymmetric structures only contribute to the scatter of the $K$ distribution. Distinguishing between central concentration and dynamically unsettled gas as the origin of high $K$ can be achieved by measuring the spectral asymmetry ($A_{\rm F}$), making the $K$-$A_{\rm F}$ plane a powerful diagnostic tool for identifying galaxies with unsettled HI using integrated spectra alone. Based on their location in the $K$-$A_{\rm F}$ plane, we find that most PSBs are not dominated by unsettled HI, but rather exhibit elevated central gas concentration. Both modes of gas redistribution in PSBs may eventually contribute to their quenching. |
| title | Decoding the Single-peaked HI Spectra of Low Redshift Post-starburst Galaxies |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2508.19545 |