Incorporating Morphological Types into Semi-analytic Schemes for Galaxy Formation

We simulate the growth of large-scale structure in the universe using a N-body code. By combining these simulations with a Monte-Carlo method, we generate galaxy distributions at present that reproduces the observed morphology-density relation, with most ellipticals concentrated in the densest regions. By "tying" each galaxy to its nearest particle, we trace the trajectory of that galaxy back in time. This enables us to reconstruct the distribution of galaxies at high redshif...

We use semi-analytical modelling of galaxy formation to predict the redshift-size-evolution of elliptical galaxies. Using a simple model in which relative sizes of elliptical galaxies of a given mass correlate with the fraction of stars formed in a star burst during a major merger event, we are able to reproduce the observed size redshif t evolution. The size evolution is a result of the amount of cold gas available during the major merger. Mergers at high redshifts are gas-r...

Any realistic theory of galaxy formation must be set in the context of a model for the formation of structure in the universe. We describe a powerful approach -- semi-analytic modelling -- that combines a set of simple rules describing the gas processes involved in galaxy formation with a scheme to follow the hierarchical growth of dark matter haloes. Surprisingly few free parameters are required to specify the model, and these are fixed with reference to a subset of local ob...

Chemical and photometric models of elliptical galaxies with infall of primordial gas, and subsequent ejection of processed material via galactic winds, are described. Ensuring that these models are consistent with the present-day colour-luminosity relation and the measured intracluster medium (ICM) abundances, we demonstrate that the initial mass function (IMF) must be significantly flatter (i.e., x<=0.80) than the canonical Salpeter slope (i.e., x=1.35). Such a ``top-heavy''...

The luminosity dependence of kinematical and isophotal properties of elliptical galaxies is investigated using numerical simulations of galaxy merging, combined with semi-analytical models of hierarchical structure formation. Mergers of spiral galaxies as the only formation mechanism for elliptical galaxies can neither reproduce the kinematical and photometric properties of very massive elliptical galaxies nor the change from rotationally flattened disky to anisotropic boxy s...

I present a biased review of when the epoch of formation of galaxies (both disks and ellipticals) maybe took place. I base my arguments in simple (mostly) analytic models that have been recently developed to reproduce most of the observed photometric, chemical and dynamical properties of galaxies both at low and high redshift.

A review of the present observational and theoretical status of elliptical galaxies is presented with the aim to clarify whether the monolithic or the hierarchical, is a more viable scenario for the origin of these structures. We describe the dynamical structure of elliptical galaxies using photometric and spectroscopic data, in particular 3D observations from integral field spectrographs, with emphasis on properties such as brightness distribution, velocity profiles, central...

Recent work has suggested that the amplitude of the size mass relation of massive early type galaxies evolves with redshift. Here we use a semi-analytical galaxy formation model to study the size evolution of massive early type galaxies. We find this model is able to reproduce the amplitude of present day amplitude and slope of the relation between size and stellar mass for these galaxies, as well as its evolution. The amplitude of this relation reflects the typical compactne...

The traditional view of elliptical galaxies has been that they formed in a single, rapid burst of star formation at high redshift, and have evolved quiescently since that time. In opposition to this traditional view is evidence that at least some elliptical galaxies have formed from the merger of two disk galaxies. What has not been clear is which process is the dominant formation mechanism for the large majority of elliptical galaxies. This question has significant implicati...

We revisit the scaling relations and star-forming histories of local elliptical galaxies using a novel selection method applied to the Sloan Digital Sky Survey DR7. We combine two probability-based automated spectroscopic and morphological classifications of about 600000 galaxies with z<0.25 to isolate true elliptical galaxies. Our sample selection method does not introduce artificial cuts in the parameters describing the galaxy but instead it associates to every object a wei...