New Evolutionary Synthesis Tool for Modelling Young Star Clusters in Merging Galaxies

Globular cluster systems (GCSs) are vital tools for investigating the violent star formation histories of their host galaxies. This violence could e.g. have been triggered by galaxy interactions or mergers. The basic observational properties of a GCS are its luminosity function and color distributions (number of clusters per luminosity resp. color bin). A large number of observed GCSs show bimodal color distributions, which, by comparison with evolutionary synthesis (ES) models, can be translated into bimodality in metallicity and/or age. An additional uncertainty comes into play when one considers extinction within the host galaxy. These effects can be disentangled either by obtaining spectroscopic data for the clusters or by imaging observations in at least four passbands. This allows us then to discriminate between various formation scenarios of GCSs, e.g. the merger scenario by Ashman & Zepf and the multi-phase collapse model by Forbes et. al.. Young and metal-rich star cluster populations are seen to form in interacting and merging galaxies. We analyse multi-wavelength broad-band observations of these young cluster systems provided by the ASTROVIRTEL project.Comment: 6 pages, 6 figures, to appear in ESO Astrophysics Symposia 'Extragalactic Globular Cluster Systems', ed. by M. Kissler-Pati

Optimal Convergence Rates Results for Linear Inverse Problems in Hilbert Spaces

In this paper, we prove optimal convergence rates results for regularisation methods for solving linear ill-posed operator equations in Hilbert spaces. The result generalises existing convergence rates results on optimality to general source conditions, such as logarithmic source conditions. Moreover, we also provide optimality results under variational source conditions and show the connection to approximative source conditions

Perturbations in Bouncing Cosmological Models

I describe the features and general properties of bouncing models and the evolution of cosmological perturbations on such backgrounds. I will outline possible observational consequences of the existence of a bounce in the primordial Universe and I will make a comparison of these models with standard long inflationary scenarios.Comment: 9 pages, no figure

On red shifs in the transition region and corona

We present evidence that transition region red-shifts are naturally produced in episodically heated models where the average volumetric heating scale height lies between that of the chromospheric pressure scale height of 200 km and the coronal scale height of 50 Mm. In order to do so we present results from 3d MHD models spanning the upper convection zone up to the corona, 15 Mm above the photosphere. Transition region and coronal heating in these models is due both the stressing of the magnetic field by photospheric and convection `zone dynamics, but also in some models by the injection of emerging magnetic flux.Comment: 8 pages, 9 figures, NSO Workshop #25 Chromospheric Structure and Dynamic