The SAMI galaxy survey : understanding observations of large-scale outflows at low redshift with EAGLE simulations

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Tescari, E., Cortese, L., Power, C., Wyithe, J. S. B., Ho, I.- T., Crain, R. A., Bland-Hawthorn, J., Croom, S. M., Kewley, L. J., Schaye, J., Bower, R. G., Theuns, T., Schaller, M., Barnes, Luke A. (R19196), Brough, S., Bryant, J. J., Goodwin, M., Gunawardhana, M. L. P., Lawrence, J. S., Leslie, S. K., Lopez-Sanchez, A. R., Lorente, N. P. F., Medling, A. M., Richards, S. N., Sweet, S. M., Tonini, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: U.K., Oxford University Press 2018
• Subjects: XXXXXX - Unknown; sami
• Online Access: https://doi.org/10.1093/mnras/stx2315; https://hdl.handle.net/1959.7/uws:64574

This work presents a study of galactic outflows driven by stellar feedback. We extract main-sequence disc galaxies with stellar mass 10(9) <= M-*/M-circle dot <= 5.7 x 10(10) 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 (s) 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 sigma-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 (Sigma(SFR)), with low-M*/low-Sigma(SFR) galaxies showing a narrow peak at low sigma (similar to 30 km s(-1)) and more active, high-M-*/high-Sigma(SFR) galaxies reaching sigma > 150 km s(-1). Although supernova-driven galactic winds in the EAGLE simulations may not entrain enough gas with T < 10(5) 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 sigma-distribution. The following equivalence relations hold in EAGLE: (i) low-sigma peak double left right arrow disc of the galaxy double left right arrow gas with T < 10(5) K; (ii) high-sigma tail double left right arrow galactic winds double left right arrow gas with T >= 10(5) K.