Using weakly nonlinear conditional PDF for the density field around an overdense region we find that the expected density contrast around a peak is always smaller while its rms fluctuation larger than in the linear case. We apply these results to the spherical model of collapse as developed by Hoffman & Shaham (1985) and find that in the case of open Universe the effect of weakly nonlinear inte...

The return of the 1998 Giacobinid meteor shower associated with the comet 21P/Giacobini-Zinner was observed by meteor radar at Ondřejov, Czech Republic. The duration of the intense part of the shower was approximately 3 hours. Though the limiting magnitude of the radar is +8 Mr, only overdense echoes down to +4.2 Mr were analyzed. A maximum number of 82 such shower meteors was recorded in the t...

We present deep observations taken with the HST Advanced Camera for Surveys of the central massive galaxy in a forming cluster at z = 2.2. The galaxy hosting the powerful radio source MRC 1138–262 is associated with one of the most extensive merger systems known in the early universe. Our HST/ACS image shows many star-forming galaxies merging within a ∼200 kpc region that emits both diffuse lin...

ABSTRACTf Overdense, metal-rich regions, shielded from stellar radiation might remain neutral throughout reionization and produce metal as well 21 cm absorption lines. Simultaneous metals can complement each other probes of underlying gas properties. We use Aurora, a suite high-resolution radiation-hydrodynamical simulations galaxy formation, to investigate the occurrence such ‘aligned’ absorbe...