Infrared Imaging Surveyor (IRIS, officially Astro-F) is a satellite which will be launched in the winter of 2003. The main purpose of the IRIS mission is an all sky survey in the mid- and far-IR with a flux limit much deeper than that of IRAS. In order to examine the performance of the survey and to find a suitable set of bandpasses for tracing galaxy evolution and picking up protogalaxy candidates as effective as possible using IRIS, we estimated the FIR galaxy counts based on a simple model with various sets of cosmological parameters and evolution types.

We investigated the environment of the radio-loud quasar 1335.8+2834 at z = 1.086 where an excess surface number density of galaxies was reported by Huthings et al. (1993). By obtaining near-infrared and new deep optical images of the field, we found a clustering of objects with very red optical-NIR color, 4 < R - K < 6 and 3 < I - K < 5 near the quasar. The colors and magnitude of the reddest objects are consistent with those predicted for old (2–4 Gyr) passively evolving elliptical galaxies at z = 1.1.

A large sample of QSOs/AGNs with detectable host galaxies is important to study the relations between the properties of the host and nucleus. Relatively faint active nuclei are of particular interest since they represent the low luminosity part of the QSO luminosity function, whose cosmological evolution is still poorly known. The non-stellar colors criterion cannot be applied to extended objects since most galaxies appear as non-stellar in color space. We have selected a sample of candidate AGNs with extended image structure on the basis of their variability, extending a previous survey for variability in objects with stellar structure (Trèvese et al. 1989, A J, 98, 108; 1994, ApJ, 433, 494). The new sample allows a comparison with different selection techniques and increases the completeness of our previous survey. We add to the previously published spectroscopic observations new data providing the confirmation of some additional candidates. Presently we have 5 confirmed candidates from our primary sample of 16 objects brighter than BJ = 22 (Bershady, Trèvese, & Kron 1997, ApJ, in press). Since it is likely that our sample contains some additional bona fide AGNs, further spectroscopic work is desirable. We can put a lower limit of 106±20 deg−2 on the surface density of AGNs brighter than BJ=22.0 mag. The newly detected extended AGNs are at least ten times fainter than MB=-23 mag and represent 13 % of the total number of AGNs.

We have carried out over 120 galaxy formation N-body simulations modeling gravity, gas dynamics and star formation using TREESPH on a parallel computer. Our aims were to investigate whether or not numerical galaxies formed from idealized cosmological perturbations can account for the Hubble sequence and the diversity of disk galaxies observed in the field.

Using a TREESPH code modified to run on a parallel computer and a new algorithm for modeling star formation, we have investigated the formation of disk galaxies from idealized cosmological perturbations.

The results from Hubble Space Telescope's Medium Deep Survey and Deep Fields indicate that there exists far more blue spiral galaxies at the intermediate and high redshifts than at the present epoch. A natural question therefore is: what have become of these excess late type galaxies as the Universe aged?

The Next Generation Space Telescope (NGST) is a key element in NASA's Origins program. The primary goals for the NGST are observing the origins of stars, galaxies, and the elements that are necessary for life. To reach those goals, the telescope must work in the near and mid-infrared – at wavelengths where the Earth's atmosphere outshines the distant galaxies by up to 8 orders of magnitude. NASA, industry, US astronomers and international collaborators have completed the initial feasibility study and have begun the development of the technologies required to make the mission affordable and ready to launch by 2007.