Ciraulo, B Mazzilli, Fisher, D B, Elliott, R, Fraser-McKelvie, A, Hayden, M R, Martig, M., van de Sande, J., Battisti, A. J., Bland-Hawthorn, J., Bolatto, A. D., Brown, T. H., Catinella, B., Combes, F., Cortese, L., Davis, T. A.  ORCID: https://orcid.org/0000-0003-4932-9379, Emsellem, E., Gadotti, D. A., del P Lagos, C., Lin, X., Marasco, A., Peng, E., Pinna, F., Puzia, T. H., Silva-Lima, L. A., Valenzuela, L. M., van de Ven, G. and Wang, J.
2025.
The GECKOS Survey: Resolved, multiphase observations of mass-loading and gas density in the galactic wind of NGC 4666.
Monthly Notices of the Royal Astronomical Society
, staf1875.
10.1093/mnras/staf1875
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Abstract
We present a multiphase, resolved study of the galactic wind extending from the nearby starburst galaxy NGC 4666. For this we use VLT/MUSE observations from the GECKOS program and H i data from the WALLABY survey. We identify both ionised and H i gas in a biconical structure extending to at least z ∼8 kpc from the galaxy disk, with increasing velocity offsets above the midplane in both phases, consistent with a multiphase wind. The measured electron density, using [S ii], differs significantly from standard expectations of galactic winds. We find electron density declines from the galaxy centre to ∼2 kpc, then rises again, remaining high (∼100 − 300 cm−3) out to ∼5 kpc. We find that H i dominates the mass loading. The total H i mass outflow rate (above z > 2 kpc) is between $5-13~{\rm M}_{\odot }~\rm yr^{-1}$, accounting for uncertainties from disk-blurring and group interactions. The total ionised mass outflow rate (traced by Hα) is between $0.5~{\rm M}_{\odot }~\rm yr^{-1}$ and $5~{\rm M}_{\odot }~\rm yr^{-1}$, depending on ne(z) assumptions. From ALMA/ACA observations, we place an upper-limit on CO flux in the outflow which correlates to $\lesssim 2.9~{\rm M}_{\odot }~\rm yr^{-1}$. We also show that the entire outflow is not limited to the bicone, but a secondary starburst at the edge generates a more widespread outflow, which should be included in simulations. The cool gas in NGC 4666 wind has insufficient velocity to escape the halo of a galaxy of its mass, especially because most of the mass is present in the slower atomic phase. This strong biconical wind contributes to gas cycling around the galaxy.
| Item Type: | Article |
|---|---|
| Date Type: | Published Online |
| Status: | Published |
| Schools: | Schools > Physics and Astronomy |
| Additional Information: | License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2025-11-04 |
| Publisher: | Oxford University Press |
| ISSN: | 0035-8711 |
| Last Modified: | 17 Nov 2025 15:30 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/182461 |
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