The SAMI Galaxy Survey: Gas velocity dispersions in low-z star-forming galaxies and the drivers of turbulence

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Varidel, Mathew R, Croom, Scott M, Lewis, Geraint F, Fisher, Deanne B, Glazebrook, Karl, Catinella, Barbara, Cortese, Luca, Krumholz, Mark R, Bland-Hawthorn, Joss, Bryant, Julia J, Groves, Brent, Brough, Sarah, Federrath, Christoph, Lawrence, Jon S, Lorente, Nuria P, Owers, Matt S, Richards, Samuel N, López-Sánchez, Ángel R, Sweet, Sarah M, van de Sande, Jesse, Vaughan, Sam P
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press 2020
• Subjects: Space and Planetary Science; Astronomy and Astrophysics; sami
• Online Access: https://espace.library.uq.edu.au/view/UQ:5f7d33b

We infer the intrinsic ionized gas kinematics for 383 star-forming galaxies across a range of integrated star formation rates (SFR ∈ [10−3, 102] M⊙ yr−1) at z ≲ 0.1 using a consistent 3D forward-modelling technique. The total sample is a combination of galaxies from the Sydney-AAO Multiobject Integral field Spectrograph (SAMI) Galaxy survey and DYnamics of Newly Assembled Massive Objects survey. For typical low-z galaxies taken from the SAMI Galaxy Survey, we find the vertical velocity dispersion (σv,z) to be positively correlated with measures of SFR, stellar mass, H i gas mass, and rotational velocity. The greatest correlation is with SFR surface density (ΣSFR). Using the total sample, we find σv,z increases slowly as a function of integrated SFR in the range SFR ∈ [10−3, 1] M⊙ yr−1 from 17 ± 3 to 24 ± 5 km s−1 followed by a steeper increase up to σv,z ∼80 km s−1 for SFR ≳ 1 M⊙ yr−1. This is consistent with recent theoretical models that suggest a σv,z floor driven by star formation feedback processes with an upturn in σv,z at higher SFR driven by gravitational transport of gas through the disc.