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Durham University

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Publication details for Prof Ray Sharples

Harrison, C.M., Johnson, H.L., Swinbank, A.M., Stott, J.P., Bower, R.G., Smail, I., Tiley, A.L., Bunker, A.J., Cirasuolo, M., Sobral, D., Sharples, R.M., Best, P., Bureau, M., Jarvis, M.J. & Magdis, G. (2017). The KMOS Redshift One Spectroscopic Survey (KROSS): rotational velocities and angular momentum of z ≈ 0.9 galaxies. Monthly Notices of the Royal Astronomical Society 467(2): 1965-1983.

Author(s) from Durham


We present dynamical measurements for 586 Hα detected star-forming galaxies from the KMOS (K-band Multi-Object Spectrograph) Redshift One Spectroscopic Survey (KROSS). The sample represents typical star-forming galaxies at this redshift (z = 0.6–1.0), with a median star formation rate of ≈7 M⊙ yr−1 and a stellar mass range of log (M⋆[M⊙])≈9–11. We find that the rotation velocity-stellar mass relationship (the inverse of the Tully-Fisher relationship) for our rotationally-dominated sources (VC/σ0 > 1) has a consistent slope and normalisation as that observed for z = 0 disks. In contrast, the specific angular momentum (j⋆; angular momentum divided by stellar mass), is ≈0.2–0.3 dex lower on average compared to z = 0 disks. The specific angular momentum scales as
j s ∝M 0.6±0.2 ⋆
, consistent with that expected for dark matter (i.e.,
j DM ∝M 2/3 DM
). We find that z ≈ 0.9 star-forming galaxies have decreasing specific angular momentum with increasing Sérsic index. Visually, the sources with the highest specific angular momentum, for a given mass, have the most disk-dominated morphologies. This implies that an angular momentum–mass–morphology relationship, similar to that observed in local massive galaxies, is already in place by z ≈ 1.