The HI Tully-Fisher relation of early-Type galaxies

Milan Den Heijer, Tom A. Oosterloo, Paolo Serra, Gyula I G Józsa, Jürgen Kerp, Raffaella Morganti, Michele Cappellari, Timothy A. Davis, Pierre Alain Duc, Eric Emsellem, Davor Krajnović, Richard M. McDermid, Torsten Naab, Anne Marie Weijmans, P. Tim De Zeeuw

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    49 Citations (Scopus)

    Abstract

    We study the HiK-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 (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/Lfor 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.

    Original languageEnglish
    Article numberA98
    Pages (from-to)1-11
    Number of pages11
    JournalAstronomy and Astrophysics
    Volume581
    DOIs
    Publication statusPublished - 1 Sept 2015

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