相关论文: Conundrum of the Large Scale Streaming
Observations have repeatedly confirmed the presence of large-scale peculiar motions in the universe, commonly referred to as ``bulk flows''. These are vast regions of the observable universe, typically spanning scales of several hundred…
The accelerating expansion of the Universe at recent epochs has called into question the validity of general relativity on cosmological scales. One probe of gravity is a comparison of expansion history of the Universe with the history of…
Streaming instability is a privileged channel to bridge the gap between collisional growth of dust grains and planetesimal formation triggered by gravity. This instability is thought to develop through its secular mode, which is long-time…
Recent surveys seem to support bulk peculiar velocities well in excess of those anticipated by the standard cosmological model. In view of these results, we consider here some of the theoretical implications of large-scale drift motions. We…
We present numerical simulations of dust clumping and planetesimal formation initiated by the streaming instability with self-gravity. We examine the variability in the planetesimal formation process by employing simulation domains with…
A theory of clustering of inertial particles advected by a turbulent velocity field caused by an instability of their spatial distribution is suggested. The reason for the clustering instability is a combined effect of the particles inertia…
A simple model of how objects of different masses stream towards each other as they cluster gravitationally is described. The model shows how the mean streaming velocity of dark matter particles is related to the motions of the parent dark…
The gravitational field of a massive object (for instance, of a galaxy group or cluster) disturbs the Hubble stream, decreasing its speed. Dependence $v(r_0)$ of the radial velocity of the stream from the present-day radius $r_0$ can be…
The formation of globular clusters and their relation to the distribution of dark matter have long puzzled astronomers. One of the most recently-proposed globular cluster formation channels ties ancient star clusters to the large-scale…
Bulk peculiar flows are commonplace in the universe, with many surveys reporting their presence on scales spanning between few hundred and several hundred Mpc. However, the sizes and the speeds of some of these bulk flows are well in excess…
We consider inertial particles suspended in an incompressible turbulent flow. Due to inertia of particles, their velocity field acquires small compressible component. Its presence leads to a new qualitative effect --- possibility of…
What is the role of clusters of galaxies in probing the large-scale velocity field of the universe? We investigate the distribution of peculiar velocities of clusters of galaxies in the popular low-density ($\Omega=0.3$) flat…
Peculiar velocities of clusters of galaxies can be measured by studying the fluctuations in the cosmic microwave background (CMB) generated by the scattering of the microwave photons by the hot X-ray emitting gas inside clusters. While for…
I summarize both observational and theoretical developments in the last few years in measuring and understanding the large-scale velocity field of galaxies, with special attention to the bulk flow, or average peculiar velocity, within…
Peculiar velocities are the motions of galaxies due to the gravitational influence of large-scale structure, and thus are an important cosmological probe of the underlying matter density field. In recent years the number of surveys designed…
Streaming instability is a powerful mechanism which concentrates dust grains in pro- toplanetary discs, eventually up to the stage where they collapse gravitationally and form planetesimals. Previous studies inferred that it should be…
Clusters of galaxies are large gravitationally bound systems which consist of several observable components: hundreds of galaxies, hot gas between the galaxies and sometimes relativistic particles. These components are emitting in different…
We review the use of peculiar velocities of galaxies as a probe of cosmological models. We put particular emphasis on comparison of the peculiar velocity and density fields, focussing on the discrepancies between various recent analyses. We…
Reviews observational situation in the measurement of peculiar velocities in the local universe. Emphasis is placed on such topics as: Do spirals and ellipticals yield the same peculiar velocity field? What is the cluster velocity…
By virtue of their high galaxy space densities and their large spatial separations, clusters are efficient and accurate tracers of the large-scale density and velocity fields. Substantial progress has been made over the past decade in the…