Evolutionary Synthesis Models for Galaxy Transformation in Clusters

Abstract

The galaxy population in rich local galaxy clusters shows a ratio of one quarter elliptical galaxies, two quarters S0 galaxies, and one quarter spiral galaxies. Observations of clusters at redshift 0.5 show a perspicuously different ratio, the dominant galaxy type are spiral galaxies with a fraction of two quarters while the number of S0 galaxies decreases to a fraction of one quarter (Dressler et al. 1997). This shows an evolution of the galaxy population in clusters since redshift 0.5 and it has been suspected that galaxy transformation processes during the infall into a cluster are responsible for this change. These could be merging, starburst or rampressure stripping. We use our evolutionary synthesis models to describe various possible effects of those interactions on the star formation of spiral galaxies infalling into clusters. We study the effects of starbursts of various strengths as well as of the truncation of star formation at various epochs on the color and luminosity evolution of model galaxies of various spectral types. As a first application we present the comparison of our models with observed properties of the local S0 galaxy population to constrain possible S0 formation mechanisms in clusters. Application to other types of galaxies is planned for the future.

Globular cluster systems in low-luminosity early-type galaxies near the Fornax cluster centre

“…However, interaction between galaxies is likely to play a role in their formation history (e.g. Bicker, Fritze‐von Alvensleben & Fricke 2003; Falcón‐Barroso et al 2004; Shioya, Bekki & Couch 2004). This interaction could have triggered a starburst in NGC 1387, causing the abundant formation of metal‐rich clusters.…”

The impact of starbursts and post-starbursts on the photometric evolution of high redshift galaxies

“…These average absolute B-band luminosities and their 1-σ ranges are M B = −20.8 ± 1.7, M B = −18.1 ± 0.94, and M B = −17.0 ± 0.77 mag for E, Sb, and Sd galaxies, respectively (cf. Bicker et al 2003Bicker et al , 2004. …”

Dust properties of nearby disks: M31 case

“…Note that a large fraction of the extinction may be internal to a starburst galaxy Figure 3. The agreement between the total hydrogen column density N(H) and the color excess EB−V with respect to Kurth et al (1999) model colors of globulars (left) and with respect to colors of ellipticals (right) as predicted by the GALEV models (Bicker et al 2004). The extinction values are listed in Table 2 and correspond to RV =3.1 and χ 2 min .…”

“…It allows also to fix some of these parameters, while still varying the rest of them. The intrinsic colors of globulars were adopted from the model of Kurth et al (1999) and for the ellipticals -from Bicker et al (2004).…”

“…Summary of the χ 2 minimization. The matches of the apparent colors to the globular cluster models of Kurth et al (1999) is given in the left and to the intrinsic colors of ellipticals predicted by the GALEV models of Bicker et al (2004) is given on the right. The numbers of the targets as the same as in Table 1.…”