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The SAMI Galaxy Survey : understanding observations of large-scale outflows at low redshift with EAGLE simulations.

Tescari, E. and Cortese, L. and Power, C. and Wyithe, J. S. B. and Ho, I.-T. and Crain, R. A. and Bland-Hawthorn, J. and Croom, S. M. and Kewley, L. J. and Schaye, J. and Bower, R. G. and Theuns, T. and Schaller, M. and Barnes, L. and Brough, S. and Bryant, J. J. and Goodwin, M. and Gunawardhana, M. L. P. and Lawrence, J. S. and Leslie, S. K. and López-Sánchez, Á. R. and Lorente, N. P. F. and Medling, A. M. and Richards, S. N. and Sweet, S. M. and Tonini, C. (2018) 'The SAMI Galaxy Survey : understanding observations of large-scale outflows at low redshift with EAGLE simulations.', Monthly notices of the Royal Astronomical Society., 473 (1). pp. 380-397.

Abstract

This work presents a study of galactic outflows driven by stellar feedback. We extract main-sequence disc galaxies with stellar mass 109 ≤ M⋆/ M⊙ ≤ 5.7 × 1010 at redshift z = 0 from the highest resolution cosmological simulation of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) set. Synthetic gas rotation velocity and velocity dispersion (σ) maps are created and compared to observations of disc galaxies obtained with the Sydney-AAO (Australian Astronomical Observatory) Multi-object Integral field spectrograph (SAMI), where σ-values greater than 150 km s−1 are most naturally explained by bipolar outflows powered by starburst activity. We find that the extension of the simulated edge-on (pixelated) velocity dispersion probability distribution depends on stellar mass and star formation rate surface density (ΣSFR), with low-M⋆/low-ΣSFR galaxies showing a narrow peak at low σ (∼30 km s−1) and more active, high-M⋆/high-ΣSFR galaxies reaching σ > 150 km s−1. Although supernova-driven galactic winds in the EAGLE simulations may not entrain enough gas with T <105 K compared to observed galaxies, we find that gas temperature is a good proxy for the presence of outflows. There is a direct correlation between the thermal state of the gas and its state of motion as described by the σ-distribution. The following equivalence relations hold in EAGLE: (i) low-σ peak  ⇔ disc of the galaxy  ⇔ gas with T <105 K; (ii) high-σ tail  ⇔ galactic winds  ⇔ gas with T ≥105 K.

Item Type:Article
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1093/mnras/stx2315
Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:05 September 2017
Date deposited:17 January 2018
Date of first online publication:09 September 2017
Date first made open access:17 January 2018

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