The SAMI galaxy survey: gas velocity dispersions in low-z star-forming galaxies and the drivers of turbulence
Mathew Varidel, S. M. Croom, Geraint F. Lewis, David B. Fisher, Karl Glazebrook, Barbara Catinella, L. Cortese, Mark R. Krumholz, Joss Bland‐Hawthorn, Julia J. Bryant, Brent Groves, Sarah Brough, Christoph Federrath, Jon Lawrence, Nuria P. F. Lorente, M. S. Owers, Samuel Richards, Á. R. López-Sánchez, Sarah M. Sweet, Jesse van de Sande, Sam P Vaughan
Abstract
ABSTRACT 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.