The GECKOS Survey: resolved, multiphase observations of mass loading and gas density in the galactic wind of NGC 4666

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 ionized and H i gas in a biconical structure extending to at least $z\sim$ 8 kpc from the galaxy disc, with increasing velocity offsets above the mid-plane 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 $\sim 2$ kpc, then rises again, remaining high ($\sim 100-300$ cm$^{-3}$) out to $\sim$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 disc-blurring and group interactions. The total ionized mass outflow rate (traced by H$\alpha$) is between 0.5 and $5~{\rm M}_{\odot }~\rm yr^{-1}$, depending on $n_e(z)$ 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.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-11-03
DOI
https://doi.org/10.1093/mnras/staf1875
Primary Topic
Galaxies: Formation, Evolution, Phenomena
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article
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article

The GECKOS Survey: resolved, multiphase observations of mass loading and gas density in the galactic wind of NGC 4666

Toby Brown, Amelia Fraser-McKelvie, Joss Bland‐Hawthorn, L. Cortese et al.
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
article

The GECKOS Survey: resolved, multiphase observations of mass loading and gas density in the galactic wind of NGC 4666

Toby Brown, Amelia Fraser-McKelvie, Joss Bland‐Hawthorn, L. Cortese, Éric Emsellem, Francesca Pinna, Lucas M. Valenzuela, Antonino Marasco, Thomas H. Puzia, Barbara Catinella, Robert J. Elliott, Michael R. Hayden, David B. Fisher, Timothy A. Davis, Dimitri Alexei Gadotti, Claudia del P. Lagos, Alberto D. Bolatto, F. Combes, Junzhi Wang, Marie Martig, Andrew Battisti, Eric W. Peng, Luiz A. Silva-Lima, X. Lin
article en

Abstract

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 ionized and H i gas in a biconical structure extending to at least $z\sim$ 8 kpc from the galaxy disc, with increasing velocity offsets above the mid-plane 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 $\sim 2$ kpc, then rises again, remaining high ($\sim 100-300$ cm$^{-3}$) out to $\sim$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 disc-blurring and group interactions. The total ionized mass outflow rate (traced by H$\alpha$) is between 0.5 and $5~{\rm M}_{\odot }~\rm yr^{-1}$, depending on $n_e(z)$ 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.

Monthly Notices of the Royal Astronomical SocietyVol. 544(4)
Australian National University (AU), Herzberg Institute of Astrophysics (CA), Centre National de la Recherche Scientifique (FR), The University of Sydney (AU), University of Vienna (AT), European Southern Observatory (DE), Universidad de La Laguna (ES), Pontificia Universidad Católica de Chile (CL), Collège de France (FR), Durham University (GB), Peking University (CN), Université Paris Sciences et Lettres (FR), Observatoire de Paris (FR), Mount Stromlo Observatory (AU), UNSW Sydney (AU), Sorbonne Université (FR), Universidade Cidade de São Paulo (BR), Kavli Institute for Theoretical Sciences (CN), DAWN Center for Independent Living (US), Instituto de Astrofísica de Canarias (ES), Community Science and Data Center (US), NSF NOIRLab (US), ARC Centre of Excellence for All-sky Astrophysics (AU), Osservatorio Astronomico di Padova (IT), International Centre for Radio Astronomy Research (AU), Swinburne University of Technology (AU), Liverpool John Moores University (GB), University of Maryland, College Park (US), Cardiff University (GB), Ludwig-Maximilians-Universität München (DE), University of Oklahoma (US)
National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, Science and Industry Endowment Fund, National Radio Astronomy Observatory, Australian Government, Agenția Națională pentru Cercetare și Dezvoltare, Commonwealth Scientific and Industrial Research Organisation, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Korea Astronomy and Space Science Institute, Studienstiftung des Deutschen Volkes, Ministerio de Ciencia e Innovación, National Astronomical Observatory of Japan, Government of Western Australia, Agencia Nacional de Investigación y Desarrollo, National Science and Technology Council, HORIZON EUROPE Framework Programme, Science and Technology Facilities Council, National Institutes of Natural Sciences, European Regional Development Fund, Elitenetzwerk Bayern, Agencia Estatal de Investigación, CHIST-ERA
Openalex Percentile: Top 77%
Galaxies: Formation, Evolution, Phenomena
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