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Padova, Italy

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D'Onofrio M.,Vicolo Osservatorio | Valentinuzzi T.,Vicolo Osservatorio | Fasano G.,National institute for astrophysics | Moretti A.,National institute for astrophysics | And 10 more authors.
Astrophysical Journal Letters | Year: 2011

We report on the discovery of a relation between the stellar mass M * of early-type galaxies (hereafter ETGs), their shape, as parameterized by the Sersic index n, and their stellar mass-to-light ratio M*/L. In a three-dimensional log space defined by these variables, the ETGs populate a plane surface with small scatter. This relation tells us that galaxy shape and stellar population are not independent physical variables, a result that must be accounted for by theories of galaxy formation and evolution. © 2011. The American Astronomical Society.


Omizzolo A.,Specola Vaticana | Omizzolo A.,National institute for astrophysics | Fasano G.,National institute for astrophysics | Reverte Paya D.,GRANTECAN S.A. | And 10 more authors.
Astronomy and Astrophysics | Year: 2014

Context. This paper belongs to a series presenting the WIde Field Nearby Galaxy-cluster Survey (WINGS). The WINGS project has collected wide-field, optical (B, V), and near-infrared (J, K) imaging as well as medium resolution spectroscopy of galaxies in a sample of 76 X-ray selected nearby clusters (0.04


D'Onofrio M.,Vicolo Osservatorio | Fasano G.,National institute for astrophysics | Moretti A.,Vicolo Osservatorio | Marziani P.,National institute for astrophysics | And 12 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013

By exploiting the data base of early-type galaxy (ETG) members of the WINGS survey of nearby clusters, we address here the long debated question of the origin and shape of the Fundamental Plane (FP). Our data suggest that different physical mechanisms concur in shaping and 'tilting' the FP with respect to the virial plane (VP) expectation. In particular, a 'hybrid solution' in which the structure of galaxies and their stellar population are the main contributors to the FP tilt seems to be favoured. We find that the bulk of the tilt should be attributed to structural non-homology, while stellar population effects play an important but less crucial role. In addition, our data indicate that the differential FP tilt between the V and K band is due to a sort of entanglement between structural and stellar population effects, for which the inward steepening of colour profiles (V - K) tends to increase at increasing the stellar mass of ETGs. The same kind of analysis applied to the ATLAS3D and Sloan Digital Sky Survey (SDSS) data in common with WINGS (WSDSS throughout the paper) confirms our results, the only remarkable difference being the less important role that our data attribute to the stellar mass-to-light-ratio (stellar populations) in determining the FP tilt. The ATLAS3D data also suggest that the FP tilt depends as well on the dark matter (DM) fraction and on the rotational contribution to the kinetic energy (Vrot/σ ), thus again pointing towards the above-mentioned 'hybrid solution'. We show that the global properties of the FP, i.e. its tilt and tightness, can be understood in terms of the underlying correlation among mass, structure and stellar population of ETGs, for which, at increasing the stellar mass, ETGs become (on average) 'older' and more centrally concentrated. Finally, we show that a Malmquist-like selection effect may mimic a differential evolution of the mass-to-light ratio for galaxies of different masses. This should be taken into account in the studies investigating the amount of the so-called 'downsizing' phenomenon. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

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