The enormous data of the galaxies from the future sky survey might allow us to explore the time evolution of the galaxy distribution. It is also believed that the bias of the galaxies plays an important role for understanding the large-scale structure of the universe. In this paper, we investigate the time evolution of the bias in the stochastic formalism. Using the Egdeworth expansion, we deri...

We present results for a galaxy formation model which includes a simple treatment for the disruption of dwarf galaxies by gravitational forces and galaxy encounters within galaxy clusters. This is implemented a posteriori in a semi–analytic model by considering the stability of the cluster dark matter haloes at z = 0. We assume that a galaxy whose dark matter substructure has been disrupted wil...

We reanalyze the galaxy-mass correlation function measured by the Sloan Digital Sky Survey to obtain host dark matter halo masses at galaxy and galaxy group scales. We extend the data to galaxy clusters in the 2MASS catalog and study the relation between central galaxy luminosity and halo mass. While the central galaxy luminosity scales as ∼ M0.7−0.8 at low masses, the relation flattens to ∼ M<...

We present results for a galaxy formation model that includes a simple treatment for the disruption of dwarf galaxies by gravitational forces and galaxy encounters within galaxy clusters. This is implemented a posteriori in a semi-analytic model by considering the stability of cluster dark matter subhaloes at z = 0. We assume that a galaxy whose dark matter substructure has been disrupted will ...

We model gravitational collapse leading to star formation in a wide range of isolated disk galaxies using a three-dimensional, smoothed particle hydrodynamics code. The model galaxies include a dark matter halo and a disk of stars and isothermal gas. Absorbing sink particles are used to directly measure the mass of gravitationally collapsing gas. They reach masses characteristic of stellar clus...

Hubble Space Telescope (HST/ACS) images of the galaxy merger Tadpole (VV29=Arp 188=UGC 10214) are interpreted using the hydro-gravitational theory of Gibson 1996-2000 (HGT) that predicts galaxy masses within about 100 kpc (3.1×10 m) are dominated by dark halos of planetary mass primordial-fogparticles (PFPs) in dark proto-globular-star-clusters (PGCs). According to our interpretation, stars and...

We report on high spectral and spatial resolution kinematic observations of Hα emission from the Cartwheel system obtained with a scanning Fabry–Perot interferometer. Velocity fields for two galaxies were measured, for the main galaxy of the system, the Cartwheel galaxy, and for a spiral companion ∼ 25 h−1 kpc to the north. The velocity field and the rotation curve of the spiral companion shows...

I implement several DSP technique: FFT, Wiener Filter, convolution to preprocess the galaxy images and use some machine learning theories to learn and predict hand-made galaxy morphology classifications. My data and success metric are taken from a recent Kaggle competition “Galaxy Zoo The Galaxy Challenge”. I focus on three sequential algorithm modules: image analysis, data compression, and mac...

Galaxy cumulative comoving number density is commonly used to forge progenitor/descendant links between observed galaxy populations at different epochs. However, this method breaks down in the presence of galaxy mergers, or when galaxies experience stochastic growth rates. We present a simple analytic framework to treat the physical processes that drive the evolution and diffusion of galaxies w...

We study the dependence of galaxy properties on the clustercentric radius and the environment attributed to the nearest neighbor galaxy using the Sloan Digital Sky Survey (SDSS) galaxies associated with the Abell galaxy clusters. We find that there exists a characteristic scale where the properties of galaxies suddenly start to depend on the clustercentric radius at fixed neighbor environment. ...