ar X iv : a st ro - p h / 98 12 18 4 v 1 9 D ec 1 99 8 ASTROPHYSICS WITH HESSI

ar X iv : a st ro - p h / 98 12 12 1 v 1 7 D ec 1 99 8 Nuclear kpc - sized disks of spiral galaxies

A complex structure of nuclear disks of normal spiral galaxies is illustrated on the example of five galaxies, observed at 6m telescope. A problem of gravitational stability of nuclear disks is shortly discussed.

ar X iv : a st ro - p h / 98 12 16 7 v 1 9 D ec 1 99 8 LYMAN BREAK GALAXIES AT z ∼ 3 AND BEYOND

We report on the status of large surveys of photometrically selected star forming galaxies at z ∼ 3 and z ∼ 4, with particular emphasis on both the advantages and the limitations of selecting objects using the “Lyman break” technique. Current results on the luminosity functions, luminosity densities, color distribution, star formation rates, clustering properties, and the differential evolution...

ar X iv : a st ro - p h / 98 11 41 8 v 1 2 6 N ov 1 99 8 Astrophysics on the GRAPE Family of Special Purpose Computers Piet Hut Institute for Advanced Study

The GRAPE-4, the world's fastest computer in 1995-1997, has produced some major scientific results, through a wide diversity of large-scale simulations in astrophysics. Applications have ranged from planetary formation, through the evolution of star clusters and galactic nuclei, to the formation of galaxies and clusters of galaxies.

ar X iv : a st ro - p h / 98 12 32 8 v 1 1 7 D ec 1 99 8 MOND in the Early Universe

I explore some consequences of Milgrom’s modified dynamics for cosmology. There appear to be two promising tests for distinguishing MOND from CDM: (1) the rate of growth of structure and (2) the baryon fraction. These should be testable with observations of clusters at high redshift and the microwave background, respectively.

ar X iv : a st ro - p h / 98 08 21 9 v 1 2 0 A ug 1 99 8 Sgr A ∗ : A supermassive black hole or a spatially extended object ?