Related papers: Dwarf Irregular Galaxies and the Intergalactic Med…
Radio galaxies with bent jets are predominantly located in groups and clusters of galaxies. We use bent-double radio sources, under the assumption that their jets are bent by ram-pressure, to probe intragroup medium (IGM) gas densities in…
Ram-pressure stripping (RPS) is a well observed phenomenon of massive spiral galaxies passing through the hot intra-cluster medium (ICM) of galaxy clusters. For dwarf galaxies (DGs) within a cluster, the transformation from gaseous to…
Dwarf galaxies are excellent cosmological probes, because their shallow potential wells make them very sensitive to the key processes that drive galaxy evolution, including baryonic feedback, tidal interactions, and ram pressure stripping.…
In two previous papers, we presented simulations of the first galaxies in a representative volume of the Universe. The simulations are unique because we model feedback-regulated galaxy formation, using time-dependent,…
In recent years, multiple studies have reported substantial populations of large, low-surface-brightness galaxies in local galaxy clusters. Various theories that aim to explain the presence of such ultra-diffuse galaxies (UDGs) have since…
Spectroscopic studies of low-luminosity early-type galaxies are essential to understand their origin and evolution but remain challenging because of low surface brightness levels. We describe an observational campaign with the new…
Some aspects of the chemical evolution of late-type dwarf galaxies are reviewed, together with their implications on three issues of cosmological relevance: similarity to primeval galaxies, derivation of the primordial helium abundance,…
We examine the origins of the bimodality observed in the global properties of galaxies around a stellar mass of 3x10^10 M_sun by comparing the environmental dependencies of star-formation for the giant and dwarf galaxy populations. The…
40 galaxies are currently known as, or suspected to be Local Group members within a radius of 1.8 Mpc. 37 of these galaxies are dwarf galaxies with M_B > -18.5 mag. I present a compilation of the star formation histories of dwarf…
Tidal Dwarf Galaxies (TDGs) are objects presently forming from gas which has been expelled from their parent galaxies during an interaction. We observed the CO emission of a sample of 11 TDGs, of which 8 were detected. The CO is found at…
Compact groups of galaxies have posed a number of challenging questions. Intensive observational and theoretical studies are now providing answers to many of these, and at the same time, are revealing unexpected new clues about the nature…
The characteristics and properties of the stellar populations and evolutionary histories of Local Group galaxies are summarized and compared to predictions of cosmological models. No clear signature of the re-ionization epoch is observed;…
In this contribution the discovery and properties of ultra-compact dwarf galaxies are presented, and their possible origin is discussed. This new type of galaxy resides in the cores of galaxy clusters. In the fundamental plane diagram of…
We study numerically the formation of dSph galaxies. Intense star bursts, e.g. in gas-rich environments, typically produce a few to a few hundred young star clusters, within a region of just a few hundred pc. The dynamical evolution of…
We study star-formation-inducing mechanisms in galaxies through multi- wavelength measurements of a sample of dwarf galaxies in the Virgo cluster described in paper I. Our main goal is to test how star formation inducing mechanisms depend…
Low mass galaxies in the Local Group are dominated by dark matter and comprise the well studied ``dwarf Spheroidal" (dSph) class, with typical masses of $10^{9-10}M_\odot$ and also the equally numerous ``ultra faint dwarfs" (UFD),…
Could there be intermediate mass black holes in essentially all old dwarf galaxies? I argue that current observations of Active Galactic Nuclei in dwarfs allow such a radical hypothesis which provides early feedback and potentially provides…
Nearby dwarf irregular galaxies were searched for compact star clusters using data from the HST archives. Three of the galaxies were found to host both populous clusters (M_V<-9.5 at a fiducial age of 10 Myr) and super-star clusters…
We use a sample of 73 simulated satellite and central dwarf galaxies spanning a stellar mass range of $10^{5.3}-10^{9.1} M_\odot$ to investigate the origin of their stellar age gradients. We find that dwarf galaxies often form their stars…
Here I discuss recent work on brown dwarfs, massive stars and the IMF in general. The stellar IMF can be well described by an invariant two-part power law in present-day star-formation events within the Local Group of galaxies. It is nearly…