Related papers: The Hubble stream near a massive object: the exact…
To complement hydrodynamic studies of the tidal disruption of the star by a massive black hole, we present the study of stellar luminosity and its variations, produced by the strong gravitational field of the black hole during a close…
In hierarchical clustering, galaxy clusters accrete mass through the aggregation of smaller systems. Thus, the velocity field of the infall regions of clusters contains significant random motion superimposed on radial infall. Because the…
Monopole and dipole signatures of the peculiar velocity field as derived from the SFI sample of field spirals and the SCI and SC2 samples of cluster spirals are presented. The monopole exhibits no evidence of a `Hubble bubble' within 7000…
Gravitational waves propagate along null geodesics like light rays in the geometrical optics approximation, and they may have a chance to suffer from gravitational lensing by intervening objects, as is the case for electromagnetic waves.…
Most massive stars form in dense clusters where gravitational interactions with other stars may be common. The two nearest forming massive stars, the BN object and Source I, located behind the Orion Nebula, were ejected with velocities of…
Maximum Likelihood estimation of the bulk flow from radial peculiar motions of galaxies, generally assumes a constant velocity field inside the survey volume. The assumption is inconsistent with the definition of the bulk flow as the…
\def\spose#1{\hbox to 0pt{#1\hss}} \def\lta{\mathrel{\spose{\lower 3pt\hbox{$\mathchar"218$}} \raise 2.0pt\hbox{$\mathchar"13C$}}} Groups of galaxies are highly linked to cosmology: 1) groups are tidally destroyed by the tidal field of the…
The Universe has a gravitational horizon, coincident with the Hubble sphere, that plays an important role in how we interpret the cosmological data. Recently, however, its significance as a true horizon has been called into question, even…
Motivated by the recent work of Robinson and Wilczek, we evaluate the gravitational anomaly of a chiral scalar field in a Vaidya spacetime of arbitrary mass function, and thus the outgoing flux from the time-dependent horizon in that…
In this paper we investigate how observational effects could possibly bias cosmological inferences from peculiar velocity measurements. Specifically, we look at how bulk flow measurements are compared with theoretical predictions. Usually…
Velocity dispersion ($\sigma$) in stellar streams from globular clusters (GCs) is sensitive to heating by Galactic substructure, including dark matter (DM) subhalos. Recent studies have compared $\sigma$ in observed and modeled streams to…
Recent discoveries of streamer-like structures around protostellar sources challenge the traditional picture of isolated, axisymmetric star formation. Here, we present new ALMA observations of [BHB2007]1, a flat-spectrum source connected to…
Large-scale peculiar motions are believed to reflect the local inhomogeneity and anisotropy of the universe, triggered by the ongoing process of structure formation. As a result, realistic observers do not follow the smooth Hubble flow but…
Dark matter sub-halos that pass near or through a thin tidal star stream locally increase its velocity dispersion. Subsequent orbital evolution further increases the velocity dispersion and stream width, lowering the surface density of a…
It is shown in this paper that deviations of galaxy cluster lenses from spherical symmetry can render mass estimates for galaxy clusters based on the formation of large arcs systematically to high. Numerical models show that the mass needed…
We develop statistical methods for identifying star streams in the halo of the Milky Way galaxy that exploit observed spatial and radial velocity distributions. Within a great circle, departures of the observed spatial distribution from…
Gravitational waves (GWs) offer an alternative way to measure the Hubble parameter. The optimal technique, the ``bright siren'' approach, requires the identification of an electromagnetic counterpart. However, a significant fraction of…
It has recently been claimed that the Hubble Sphere represents a previously unknown limit to our view of the universe, with light we detect today coming from a proper distance less than this "Cosmic Horizon" at the present time. By…
In this paper, we investigate spherically symmetric perfect fluid gravitational collapse in metric $f(R)$ gravity. We take non-static spherically symmetric metric in the interior region and static spherically symmetric metric in the…
The helicity flux density is a novel quantity which characterizes the angle-dependence of the helicity of radiative gravitons and it may be tested by gravitational wave experiments in the future. We derive a quadrupole formula for the…