Related papers: Galaxies appear simpler than expected
A new view on our Galaxy has recently emerged, with large consequences on its formation scenarios. Not only new dwarf satellites have been detected, still orbiting and tidally disrupting, but also a multitude of stellar streams or tidal…
Galaxy evolution depends strongly on the environment. Dynamical interactions and subsequent evolution make galaxies more concentrated, with higher surface densities, and also trigger star-formation, which consumes the available cold gas.…
This article reviews the prevailing paradigm for how galaxies and larger structures formed in the universe: gravitational instability. Basic observational facts are summarized to motivate the standard cosmological framework underlying most…
A local property of standard cosmology - growth of primordial perturbations - implies at least six different formation mechanisms of dwarf galaxies. A global property - the topology of the Universe - may enable direct observational study of…
Gravitational lensing studies suggest that the Universe may contain a population of dark galaxies; we investigate this intriguing possibility and propose a mechanism to explain their nature. In this mechanism a dark galaxy is formed with a…
Using cosmological hydrodynamical simulations, we investigate the effects of hierarchical aggregation on the triggering of star formation in galactic-like objects. We include a simple star formation model to transform the cold gas in dense…
In our modern understanding of galaxy formation, every galaxy forms within a dark matter halo. The formation and growth of galaxies over time is connected to the growth of the halos in which they form. The advent of large galaxy surveys as…
The current understanding of galaxy formation is that it proceeds in a 'bottom up' way, with the formation of small clumps of gas and stars that merge hierarchically until giant galaxies are built up. The baryonic gas loses the thermal…
Eliptical and bulge galaxies share a tight correlation of velocity distribution to both luminosity and black hole mass. There are similar orbital speeds for all galaxies of a given luminosity including dark matter (DM) at large radii. The…
In models of galaxy formation in a hierarchical Universe, elliptical galaxies form through the merging of smaller disk systems. These models yield a number of testable predictions if reliable techniques for determining the relative ages and…
A major problem in extragalactic astronomy is the inability to distinguish in a robust, physical, and model independent way how galaxy populations are related to each other and to their formation histories. A similar, but distinct, and also…
Increasingly good statistical data on the galaxy population at high and low redshift enable the development of new phenomenological approaches to galaxy evolution based on application of the simplest continuity equations. This has given new…
Stars and planets are the fundamental objects of the Universe. Their formation processes, though related, may differ in important ways. Stars almost certainly form from gravitational collapse and probably have formed this way since the…
Recent surveys of star forming regions have shown that most stars, and probably all massive stars, are born in dense stellar clusters. The mechanism by which a molecular cloud fragments to form several hundred to thousands of individual…
Our Galaxy, the Milky Way, is a benchmark for understanding disk galaxies. It is the only galaxy whose formation history can be studied using the full distribution of stars from white dwarfs to supergiants. The oldest components provide us…
Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In…
The current consensus is that galaxies begin as small density fluctuations in the early Universe and grow by in situ star formation and hierarchical merging. Stars begin to form relatively quickly in sub-galactic sized building blocks…
Major progress has been made over the last few years in understanding hydrodynamical processes on cosmological scales, in particular how galaxies get their baryons. There is increasing recognition that a large part of the baryons accrete…
Galaxy growth depends critically on the interplay between radiative cooling of cosmic gas and the resulting energetic feedback that cooling triggers. This interplay has proven exceedingly difficult to model, even with large supercomputer…
We present in this paper a new three-dimensional galaxy classification system designed to account for the diversity of galaxy properties in the nearby universe. To construct this system we statistically analyse a sample of >22,000 galaxies…