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

L. Cortese, L. M R Fogarty, I. T. Ho, K. Bekki, J. Bland-Hawthorn, M. Colless, W. Couch, S. M. Croom, K. Glazebrook, J. Mould, N. Scott, R. Sharp, C. Tonini, J. T. Allen, J. Bloom, J. J. Bryant, M. Cluver, R. L. Davies, M. J. Drinkwater, M. GoodwinA. Green, L. J. Kewley, I. S. Kostantopoulos, J. S. Lawrence, S. Mahajan, A. M. Medling, M. Owers, S. N. Richards, S. M. Sweet, O. I. Wong

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


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 S0.5 parameter, which combines the contribution of both dispersion (σ) and rotational velocity (Vrot) to the dynamical support of a galaxy (S0.5 = √ 0.5 Vrot2 + σ2). Our results are independent of the baryonic component from which σ 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 σ 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 Vrot and σ 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) < 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.

Original languageEnglish
Article numberL37
Pages (from-to)1-6
Number of pages6
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - 10 Nov 2014
Externally publishedYes


  • galaxies: evolution
  • galaxies: fundamental parameters
  • galaxies: kinematics and dynamics


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