Astronomy and Astrophysics, volume 581A, 98-98 (2015/9-1)
The HI Tully-Fisher relation of early-type galaxies.
DEN HEIJER M., OOSTERLOO T.A., SERRA P., JOZSA G.I.G., KERP J., MORGANTI R., CAPPELLARI M., DAVIS T.A., DUC P.-A., EMSELLEM E., KRAJNOVIC D., McDERMID R.M., NAAB T., WEIJMANS A.-M. and TIM DE ZEEUW P.
Abstract (from CDS):
We study the Hi K-band Tully-Fisher relation and the baryonic Tully-Fisher relation for a sample of 16 early-type galaxies, taken from the ATLAS3D sample, which all have very regular Hi disks extending well beyond the optical body (>5Reff). We use the kinematics of these disks to estimate the circular velocity at large radii for these galaxies. We find that the Tully-Fisher relation for our early-type galaxies is offset by about 0.5-0.7mag from the relation for spiral galaxies, in the sense that early-type galaxies are dimmer for a given circular velocity. The residuals with respect to the spiral Tully-Fisher relation correlate with estimates of the stellar mass-to-light ratio, suggesting that the offset between the relations is mainly driven by differences in stellar populations. We also observe a small offset between our Tully-Fisher relation with the relation derived for the ATLAS3D sample based on CO data representing the galaxies' inner regions (≲1Reff). This indicates that the circular velocities at large radii are systematically 10% lower than those near 0.5-1Reff, in line with recent determinations of the shape of the mass profile of early-type galaxies. The baryonic Tully-Fisher relation of our sample is distinctly tighter than the standard one, in particular when using mass-to-light ratios based on dynamical models of the stellar kinematics. We find that the early-type galaxies fall on the spiral baryonic Tully-Fisher relation if one assumes M/LK=0.54M☉/L☉ for the stellar populations of the spirals, a value similar to that found by recent studies of the dynamics of spiral galaxies. Such a mass-to-light ratio for spiral galaxies would imply that their disks are 60-70% of maximal. Our analysis increases the range of galaxy morphologies for which the baryonic Tully-Fisher relations holds, strengthening previous claims that it is a more fundamental scaling relation than the classical Tully-Fisher relation.
galaxies: kinematics and dynamics - galaxies: elliptical and lenticular, cD
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