Related papers: Galaxies appear simpler than expected
Spiral galaxies comprise three major structural components; thin discs, thick discs, and central bulges. Relative dominance of these components is known to correlate with the total mass of the galaxy, and produces a remarkable morphological…
Observations made using large ground-based and space-borne telescopes have probed cosmic history all the way from the present-day to a time when the Universe was less than a tenth of its present age. Earlier on lies the remaining frontier,…
The morphological classification of galaxies provides vital physical information about the orbital motions of stars in galaxies, and correlates in interesting ways with star formation history, and other physical properties. Galaxy…
A growing number of low luminosity and low surface brightness astronomical objects challenge traditional notions of both galaxies and star clusters. To address this, we propose a definition of galaxy independent of the cold dark matter…
Essentially everything of astronomical interest is either part of a galaxy, or from a galaxy, or otherwise relevant to the origin or evolution of galaxies. Diverse examples are that the isotropic composition of meteorites provides clues to…
Properties of nearby dwarf galaxies are briefly discussed. Dwarf galaxies vary widely in their star formation histories, the ages of their subpopulations, and in their enrichment history. Furthermore, many dwarf galaxies show evidence for…
Nearly a century after the true nature of galaxies as distant "island universes" was established, their origin and evolution remain great unsolved problems of modern astrophysics. One of the most promising ways to investigate galaxy…
We use a new fiber spectroscopic survey of 12 nearby, poor groups of galaxies to examine the dynamics and evolution of galaxies in these common, but poorly studied, environments. Some of our conclusions are: (1) The nine groups in our…
Our knowledge of the Universe remains discovery-led: in the absence of adequate physics-based theory, interpretation of new results requires a scientific methodology. Commonly, scientific progress in astrophysics is motivated by the…
The intrinsic properties of galaxies are influenced by their environments, underscoring the environment's critical role in galaxy formation and evolution. Traditionally, these environments are categorized into four fixed classifications:…
Current ideas on the formation of the Galaxy are reviewed. Many of the observed characteristics of our Milky Way System are consistent with a scenario in which the Galaxy formed inside out, with the inner part of it evolving by rapid…
Advances in extragalactic astronomy have prompted the development of increasingly realistic models which aim to describe the formation and evolution of galaxies. We review the philosophy behind one such technique, called semi-analytic…
Formation process(es) of galactic bulges are not yet clarified although several mechanisms have been proposed. In a previous study, we suggested one possibility that galactic bulges have been formed from the cold gas inflowing through…
Galaxies are built by complex physical processes with significant inherent stochasticity. It is therefore surprising that the inferred dark matter distributions in galaxies are strongly correlated with the observed baryon distributions…
In this review, I provide an overview of theoretical aspects related to the evolution of galaxies as a function of environment. I discuss the main physical processes at play, their characteristic time-scales and environmental dependency,…
Gravitational interactions and mergers are shaping and reshaping galaxies throughout the observable universe. While observations of interacting galaxies at low redshifts yield detailed information about the processes at work, observations…
There is accumulating evidence that the faint end of the galaxy luminosity function might be very different in different locations. The luminosity function might be rising in rich clusters and flat or declining in regions of low density. If…
Galaxies accrete their mass by means of both smooth accretion from the cosmic web, and the mergers of smaller entities. We wish to quantify the respective role of these two modes of accretion, which could determine the morphological types…
Cosmic structure originated from minute density perturbations in an almost homogeneous universe. The first stars are believed to be very massive and luminous, providing the first ionizing radiation and heavy elements to the universe and…
According to the current paradigm, galaxies form and reside in extended cold dark matter (CDM) halos and in turn are key tracers of cosmological structure. Understanding how different types of galaxies occupy halos of different masses is…