The SAMI Galaxy Survey: toward a unified dynamical scaling relation for galaxies of all types

• Published in: The Astrophysical Journal
• 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., Scott, N., Sharp, R., Tonini, C., Allen, J. T., Bloom, J., Bryant, J. J., Cluver, M., Davies, R. L., Drinkwater, M. J., Goodwin, M., Green, A., Kewley, L. J., Kostantopoulos, I. S., Lawrence, J. S., Mahajan, S., Medling, A. M., Owers, M., Richards, S. N., Sweet, S. M., Wong, O. I.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Institute of Physics Publishing 2014
• Subjects: Galaxies: evolution; Galaxies: fundamental parameters; Galaxies: kinematics and dynamics; Tully-Fisher relation; Digital sky survey; To-light ratios; Spiral galaxies; Disk galaxies; S0 galaxies; Field; Hexabundles; Kinematics; Dispersion; 1912 Space and Planetary Science; 3103 Astronomy and Astrophysics; sami
• Online Access: https://espace.library.uq.edu.au/view/UQ:348846/thumbnail_UQ348846_OA_t.jpg; https://espace.library.uq.edu.au/view/UQ:348846/UQ348846_OA.pdf; https://espace.library.uq.edu.au/view/UQ:348846

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-*) to internal velocity quantified by the S-0.5 parameter, which combines the contribution of both dispersion (sigma) and rotational velocity (V-rot) to the dynamical support of a galaxy (S-0.5 = root 0.5 V-rot(2) + sigma(2)). Our results are independent of the baryonic component from which sigma and V-rot are estimated, as the S-0.5 of stars and gas agree remarkably well. This represents a significant improvement compared to the canonical M-* versus Vrot and M-* versus s 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-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-*/M-circle dot) < 11. Such relation appears to be more general and at least as tight as any other dynamical scaling relation, representing a unique tool for investigating the link between galaxy kinematics and baryonic content, and a less biased comparison with theoretical models.