Volume 581, September 2015
|Number of page(s)||11|
|Published online||11 September 2015|
The H I Tully-Fisher relation of early-type galaxies
Argelander Institut für Astronomie (AIfA), University of
Bonn, Auf dem Hügel
2 Max-Planck Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany
3 ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
4 Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
5 CSIRO Astronomy and Space Science, Australia Telescope National Facility, PO Box 76, Epping, NSW 1710, Australia
6 SKA South Africa Radio Astronomy Research Group, 3rd Floor, The Park Park Road Pinelands, 7405, South Africa
7 Rhodes University, Department of Physics and Electronics, Rhodes Centre for Radio Astronomy, Techniques & Technologies, PO Box 94, Grahamstown 6140, South Africa
8 Sub-Department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
9 Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts AL1 9AB, UK
10 Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp – CNRS – Université Paris Diderot, 91191 Gif-sur-Yvette Cedex, France
11 European Southern Observatory, Karl-Schwarzschild-Straße 2, 85738 Garching, Germany
12 Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
13 Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia
14 Australian Gemini Office, Australian Astronomical Observatory, PO Box 915, Sydney, NSW 1670, Australia
15 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85741 Garching, Germany
16 School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
17 Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
Received: 3 July 2015
Accepted: 14 July 2015
We study the H iK-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 H i disks extending well beyond the optical body (≳ 5 Reff). 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 0.5-0.7 mag 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 (≲1 Reff). This indicates that the circular velocities at large radii are systematically 10% lower than those near 0.5−1 Reff, 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 = 0.54 M⊙/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.
Key words: galaxies: kinematics and dynamics / galaxies: elliptical and lenticular, cD
© ESO, 2015
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