Large scale stellar kinematic profiles

We study the balance in dynamical (rotational versus pressure) support of nearly 400 galaxies with stellar kinematics out to $\ge1.5R_e$ in the Sydney AAO Multi Integral Feld (SAMI) Galaxy Survey. We present $V/\sigma$ and local spin radial profiles. Although there is a broad range in amplitude, most kinematic profiles are self similar and monotonously increase across the probed radial range. We find very few galaxies with the dramatic kinematic transition expected between in-situ and accreted stars. We compare the $V/\sigma$ gradient and maximum values to the visual morphologies of the galaxies to better understand the link between visual and kinematic morphologies.

We find that the dynamical support of galaxies is linked to their visual morphology. Late-type systems have higher rotational support and steeper $V/\sigma$ gradients compared to early-type galaxies. On average, the visual morphology of galaxies reflects their dynamical state, although we observe considerable scatter and are plagued by the inevitable dependence on inclination.

We perform a search for so-called ``embedded discs'', which are kinematically cold discy structures embedded within large scale bulges. A careful visual inspection of the kinematics reveals only 2 galaxies harbouring embedded discs. This is more than an order of magnitude fewer than identified in some previous studies. The reason for this tension could be due to differences in the sample selection between various studies of the large scale kinematics of galaxies.

PAPER USES: Stellar mass estimates, MGE fits, stellar kinematics and visual morphologies.

Publication Date: 
May 2018
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