Related papers: The Hierarchical Formation of the Galactic Disk
I briefly review the growing evidence that thick stellar disks surround most edge-on disk galaxies. Recent studies show that these extragalactic thick disks have old ages, low metallicities, long scale lengths, and moderately flattened…
How do galaxies move relative to one another? While we can examine the motion of dark matter subhalos around their hosts in simulations of structure formation, determining the orbits of satellites around their parent galaxies from…
Correlations between stellar kinematics and chemical abundances are fossil evidence for evolutionary connections between Galactic structural components. Extensive stellar surveys show that the only tolerably clear distinction between…
It is widely believed that star clusters form with low star formation efficiencies. With the onset of stellar winds by massive stars or finally when the first super nova blows off, the residual gas is driven out of the embedded star…
Spiral galaxies offer a unique opportunity to study the role of star formation in galaxy evolution and to test various theoretical star formation schemes. I review some recent relevant work on the evolution of spiral galaxies. Detailed…
The Galactic disk retains a vast amount of information about how it came to be, and how it evolved over cosmic time. However, we know very little about the secular processes associated with disk evolution. One major uncertainty is the…
Using test particle simulations we examine the structure of the outer Galactic disk as it is perturbed by a satellite in a tight eccentric orbit about the Galaxy. A satellite of mass a few times 10^9 Msol can heat the outer Galactic disk,…
We use numerical simulations to investigate the orbital characteristics of tidal debris from satellites whose orbits are dragged into the plane of galactic disks by dynamical friction before disruption. We find that these satellites may…
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…
Counterrotating stars in disk galaxies are a puzzling dynamical feature whose origin has been ascribed to either satellite accretion events or to disk instabilities triggered by deviations from axisymmetry. We use a cosmological simulation…
We study the distribution of orbital eccentricities of stars in thick disks generated by the heating of a pre-existing thin stellar disk through a minor merger (mass ratio 1:10), using N-body/SPH numerical simulations of interactions that…
Disk accretion may be the fundamental astrophysical process. Stars and planets form through the accretion of gas in a disk. Black holes and galaxies co-evolve through efficient disk accretion onto the central supermassive black hole.…
The tidal disruption of a star by a supermassive black hole is expected to lead to a short bright flare followed by an extended period of low-level emission. Existing models of the late-time accretion of the stellar debris via a thin disk…
The ongoing large spectroscopic surveys of the Milky Way such as SEGUE and RAVE have enabled us to take a fresh look at the structure of the Galactic thin and thick disks, and how their structure fits within the framework of structure…
We consider the effects of eccentricity on the fragmentation of gravitationally unstable accretion disks, using numerical hydrodynamics. We find that eccentricity does not affect the overall stability of the disk against fragmentation, but…
The role that minor mergers have played in the formation and structure of the Milky Way is still an open question, about which there is much debate. We use numerical simulations to explore the evolution of debris from a tidally disrupted…
Accumulation of new data on stellar hierarchical systems and the progress in numerical simulations of their formation open the door to genetic classification of these systems, where properties of a certain group (family) of objects are…
We study the orbital properties of stars in four (published) simulations of thick disks formed by: i) accretion from disrupted satellites, ii) heating of a pre-existing thin disk by a minor merger, iii) radial migration and iv) gas rich…
Nearly all of the initial angular momentum of the matter that goes into each forming star must somehow be removed or redistributed during the formation process. The possible transport mechanisms and the possible fates of the excess angular…
Galaxy disk formation must incorporate the multiphase nature of the interstellar medium. The resulting two-phase structure is generated and maintained by gravitational instability and supernova energy input, which yield a source of…