Comparing dynamical and photometric-stellar masses of early-type galaxies at z ~ 1

¹ European Southern Observatory, Karl Schwarzschild Strasse 2, Garching bei Muenchen, 85748, Germany e-mail: arettura@eso.org
² Université Paris-Sud 11, 15 rue Georges Clemenceau, 91405 Orsay, France
³ Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd. Arago, 75014 Paris, France
⁴ Dipartimento di Scienze Fisiche, Università degli Studi di Napoli “Federico II”, via Cinthia, 80126 Napoli, Italy
⁵ NOAO, 950 North Cherry Avenue, PO Box 26732, Tucson, AZ 85726-6732, USA
⁶ ST-ECF, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
⁷ Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁸ Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁹ Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
¹⁰ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
¹¹ European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
¹² Department of Physics, University of California at Davis, 1 Shields Avenue, Davis, CA 95616-8677, USA
¹³ Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 413, PO Box 808, 7000 East Avenue, Livermore, CA 94551, USA

Received: 24 March 2006
Accepted: 11 August 2006

Abstract

Aims.The purpose of this study is to explore the relationship between galaxy stellar masses, based on multiwavelength photometry spectral template fitting and dynamical masses based on published velocity dispersion measurements, for a sample of 48 early-type galaxies at with HST/ACS morphological information.

Methods.We determine photometric-stellar masses and perform a quantitative morphological analysis of cluster and field galaxies at redshift , using ground- and space-based multiwavelength data available on the GOODS-S field and on the field around the X-ray luminous cluster RDCS1252.9-2927 at . We use multi-band photometry over 0.4–8 μm from HST/ACS, VLT/ISAAC and Spitzer/IRAC to estimate photometric-stellar masses using Composite Stellar Population (CSP) templates computed with PEGASE.2 (Fioc & Rocca-Volmerange 1997) models. We compare stellar masses with those obtained using CSPs built with Bruzual & Charlot (2003, MNRAS, 344, 1000; BC03) and Maraston (2005, MNRAS, 362, 799; M05) models. We then compare photometric-stellar mass and dynamical mass estimates as a function of morphological parameters obtained from HST/ACS imaging.

Results.Based on our sample, which spans the mass range , we find that 1) PEGASE.2, BC03, M05 yield consistent photometric-stellar masses for early-type galaxies at with a small scatter (0.15 dex rms); 2) adopting a Kroupa IMF, photometric-stellar masses match dynamical mass estimates for early-type galaxies with an average offset of 0.27 dex; 3) assuming a constant IMF, increasing dark matter fraction with the increasing galaxy mass can explain the observed trend; 4) we observe that early-type galaxies with significant disk components (Sa/Sab) or with signs of dynamical interaction tend to have the largest deviation from a one-to-one relation