On the Dn- relation for elliptical galaxies

The Infrared Diameter { Velocity Dispersion Relation for Elliptical Galaxies

Using single channel infrared photometry from the literature, a provisional K-band diameter{velocity dispersion relation for elliptical galaxies in the Coma and Virgo clusters is derived. The Coma cluster relation has 1.5 times lower scatter at K than in B or V. Excluding 4 outliers, the RMS scatter at K for 24 galaxies in Coma is only 4.8% in distance, close to the limit implied by the observa...

A metallicity-flattening relation for dwarf elliptical galaxies

It is shown that bright cluster dwarf ellipticals follow a relation between metallicity and apparent flattening. Rounder dwarfs tend to be more metal-rich. The evidence is based on colour as well as spectroscopic line-strength data from the literature. The large scatter of dEs around the mean metallicity-luminosity relation, usually ascribed to large observational errors, turns out to be an ell...

Origin of the colour-magnitude relation of elliptical galaxies

Evolutionary models of elliptical galaxies are constructed by using a new population synthesis code. Model parameters are calibrated to reproduce the observed colour-magnitude (CM) relation of Coma ellipticals in V −K vs. MV diagram. The SEDs are degenerated in stellar age and metallicity. An attempt is performed to break this degeneracy, by simulating evolution of the CM relation of elliptical...

Elliptical Galaxies

The photoionization effect of the ultraviolet background on the colour-magnitude relation of elliptical galaxies

We examined effects of the ultraviolet background radiation (UVB) on the colour– magnitude relation (CMR) of elliptical galaxies in clusters of galaxies in the hierarchical clustering scenario by using a semi-analytic model of galaxy formation. In our model the UVB photoionizes gas in dark haloes and suppresses the cooling of the diffuse hot gas onto galaxy discs. By using a semi-analytic model...