Related papers: The quest for a stable disk
(highly abridged) We define three requirements for accurate simulations that attempt to model circumstellar disks and the formation of collapsed objects (e.g. planets) within them. First, we define a resolution requirement based on the…
Growth rates for gravitational instabilities in a thick disk of gas and stars are determined for a turbulent gas that dissipates on the local crossing time. The scale heights are derived from vertical equilibrium. The accuracy of the usual…
We explore the gravitational instability of clumpy and turbulent gas discs, taking into account the Larson-type scaling laws observed in giant molecular clouds (GMCs) and HI, as well as more general scaling relations. This degree of freedom…
We perform controlled N-body simulations of disc galaxies growing within live dark matter (DM) haloes to present-day galaxies that contain both thin and thick discs. We consider two types of models: a) thick-disc initial conditions to which…
Self-gravitating stellar disks with random motion support both exponentially growing and, in some cases, purely oscillatory axisymmetric bending modes, unlike their cold disk counterparts. A razor-thin disk with even a very small degree of…
We combine deep optical and IR photometry for 326 spiral galaxies from two recent galaxy samples and report that the surface brightness profiles of late-type spirals are best fit by two exponentials. Moreover, the ratio of bulge and disk…
We carry out a detailed orbit analysis of gravitational potentials selected at different times from an evolving self-consistent model galaxy consisting of a two-component disk (stars+gas) and a live halo. The results are compared with a…
About one third of early-type barred galaxies host small-scale secondary bars. The formation and evolution of such double-barred galaxies remain far from being well understood. In order to understand the formation of such systems, we…
In this letter we study the mean sizes of Halpha clumps in turbulent disk galaxies relative to kinematics, gas fractions, and Toomre Q. We use 100~pc resolution HST images, IFU kinematics, and gas fractions of a sample of rare, nearby…
We study the structure and evolution of the very early protostellar disk (``protodisk'') just after protostar formation, where disk self-gravity dominates and the stellar contribution is dynamically minor. The disk redistributes angular…
I review the arguments for the importance of halo structure in driving galaxy evolution and coupling a galaxy to its environment. We begin with a general discussion of the key dynamics and examples of structure dominated by modes. We find…
Gravitational instabilities (GIs) are spiral distortions in a self-gravitating disk that appear wherever the local surface density and temperature become favorable for their growth. The restructuring of the disk as it becomes unstable, the…
We investigate the long-term and large-scale viscous evolution of dense planetary rings using a simple 1D numerical code. We use a physically realistic viscosity model derived from N-body simulations (Daisaka et al., 2001), and dependent on…
We present a new method to study the characteristic scales of collapse and fragmentation in galactic disks. Clump formation is seeded in simulations via controlled perturbations with a specified wavelength and velocity. These are applied to…
We study the neutral hydrogen properties of a sample of 20 bulgeless disk galaxies (Sd - Sdm Hubble types), an interesting class that can be used to constrain galaxy formation and evolution, especially the role of mergers versus internal…
We present results from the "Ponos" simulation suite on the early evolution of a massive, $M_{\rm vir}(z=0)=1.2\times 10^{13}$ M$_{\odot}$ galaxy. At $z\gtrsim6$, before feedback from a central supermassive black hole becomes dominant, the…
Gravitational instabilities play an important role in structure formation of gas-rich high-redshift disc galaxies. In this paper, we revisit the axisymmetric perturbation theory and the resulting growth of structure by taking the realistic…
We combine HST imaging from the GEMS survey with photometric redshifts from COMBO-17 to explore the evolution of disk-dominated galaxies since z<1.1. The sample is comprised of all GEMS galaxies with Sersic indices n<2.5, derived from fits…
We investigate the formation of multiple spiral modes in Milky Way-like disk-halo systems without explicitly exciting perturbations. We explore how numerical resolution, the level of local disk stability, and the presence of a live halo…
New observations in favour of a significant role of secular evolution are reviewed: central star formation boosted in pseudo-bulge barred galaxies, relations between bulge and disk, evidence for rejuvenated bulges. Numerical simulations…