THE SAMI GALAXY SURVEY: TOWARD A UNIFIED DYNAMICAL SCALING RELATION FOR GALAXIES OF ALL TYPES

• Published in: Astrophysical journal. Letters 2014-11, Vol.795 (2), p.1-6
• Main Authors: Cortese, L, Fogarty, L M R, Ho, I-T, Bekki, K, Bland-Hawthorn, J, Colless, M, Couch, W, Croom, S M, Glazebrook, K, Mould, J
• Format: Article
• Language: English
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; BARYONS; COMPARATIVE EVALUATIONS; Dispersions; GALACTIC EVOLUTION; GALAXIES; Kinematics; MASS; MORPHOLOGY; Rotation; SCALING LAWS; STARS; Stellar mass; VELOCITY
• ISSN: 2041-8213; 2041-8205; 2041-8213
• DOI: 10.1088/2041-8205/795/2/L37

We take advantage of the first data from the Sydney-AAO Multi-object Integral field Galaxy Survey to investigate the relation between the kinematics of gas and stars, and stellar mass in a comprehensive sample of nearby galaxies. We find that all 235 objects in our sample, regardless of their morphology, lie on a tight relation linking stellar mass (M[low *]) to internal velocity quantified by the S sub(0.5) parameter, which combines the contribution of both dispersion ([sigma]) and rotational velocity (V sub(rot)) to the dynamical support of a galaxy (S sub(0.5) = (ProQuest: Formulae and/or non-USASCII text omitted). Our results are independent of the baryonic component from which [sigma] and V sub(rot) are estimated, as the S sub(0.5) of stars and gas agree remarkably well. This represents a significant improvement compared to the canonical M[low *] versus V sub(rot) and M[low *] versus [sigma] relations. Not only is no sample pruning necessary, but also stellar and gas kinematics can be used simultaneously, as the effect of asymmetric drift is taken into account once V sub(rot) and [sigma] are combined. Our findings illustrate how the combination of dispersion and rotational velocities for both gas and stars can provide us with a single dynamical scaling relation valid for galaxies of all morphologies across at least the stellar mass range 8.5 < log (M[low *]/M sub([middot in circle]))