STScI Preprint #1346

The Properties of Field Elliptical Galaxies at Intermediate Redshift. I: Empirical Scaling Laws

Based on observations collected at the European Southern Observatory, La Silla and with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by Association of Universities for Research in Astronomy, Inc. (AURA), under NASA contract NAS5-26555.

We present measurements of the Fundamental Plane (FP) parameters (the effective radius, the mean effective surface brightness, and the central velocity dispersion) of six field elliptical galaxies at intermediate redshift. The imaging is taken from the Medium Deep Survey of the Hubble Space Telescope, while the kinematical data are obtained from long-slit spectroscopy using the 3.6-m ESO telescope. The Fundamental Plane appears well defined in the field even at redshift 0.3. The data show a shift in the FP zero point with respect to the local relation, possibly indicating modest evolution, consistent with the result found for intermediate redshift cluster samples. The FP slopes derived for our field data, plus other cluster ellipticals at intermediate redshift taken from the literature, differ from the local ones, but are still consistent with the interpretation of the FP as a result of homology, of the virial theorem and of the existence of a relation between luminosity and mass, L M. We also derive the surface brightness vs. effective radius relation for nine galaxies with redshift up to z 0.6, and data from the literature; the evolution that can be inferred is consistent with what is found using the FP.

Status:

Appeared in: Monthly Notices of the R.A.S.

Affiliations:

¹ Scuola Normale Superiore, P.za dei Cavalieri 7, I56126, Pisa, Italy
² Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
³ On assignment from the Space Sciences Division of the European Space Agency
⁴ On leave from the Scuola Normale Superiore, Pisa, Italy
⁵ ESO, Karl-Schwarzschild Str. 2, D85748, Garching bei München, Germany