Composite image of overdensity (blue contour) and metallicity (red contour) distribution around a star-forming galaxy at z=2.43. The enriched gas tends to escape toward the lower density regions. The filament remains unaffected by the wind. As a result, the cold accretion is still maintained through the filaments, which continues funneling gas to the galaxy. (Kawata & Rauch 2007)

Evolution of the distribution of dark matter density distribution of a group of galaxies (top), and the close-up rest-frame R-band images of an infalling disk galaxy (lower) from the face-on view. The contours correspond to the cold gas density. The arrows indicate the velocity of the galaxy with respect to the velocity of the group. After the galaxy enters the group, the cold gas displays a clear tail morphology in the direction opposite the galaxy's motion. However, we found that ram-pressure is not sufficient in the group to remove the cold disk gas. On the other hand, the majority of the hot gas in the galaxy is stripped. Since the cooling of the hot-gas component provides a source for new cold gas, the stripping of the hot component effectively cuts off the supply of cold gas, which in turn leads to a quenching of star formation. (Kawata & Mulchaey 2008)

Upper Panels: Dark Matter density evolution, Lower Panels: J band (observed frame) images of a simulated elliptical galaxy.

Predicted X-ray image which shows the blown-out phase of the hot gas.	History of the feedback energy from SNe II (red), SNe Ia (cyan) and the AGN (yellow).

Our model considers an AGN as being 'active' when a convergent gas inflow condition exists within the nucleus of a galaxy; otherwise, the AGN is assumed to remain dormant. This induces a self-regulated activity for the AGN, the result of which leads to a stable hot corona and the suppression of significant late-time star formation. These properties of our AGN heating model lead to a system consistent with both the X-ray and optical properties of comparable elliptical galaxies. (Kawata & Gibson 2005)

Distribution of the oldest stars in our galaxy (upper panel) compared with the full population of primordial stars (lower panel). While the oldest stars are all located near the center, where they are very difficult to detect, later forming stars made of gas without heavy elements should be located throughout the galaxy. The fact that no such stars have ever been detected places important scientific constraints on the properties and formation of these stars. Background image from DIRBE data, (c) Edward L. Wright (Scannapieco, Kawata, Brook, Schneider, Ferrara, Gibson 2006, press release)