The lightest supersymmetric particle, most likely the neutralino, might account for a large fraction of dark matter in the Universe. We show that the primordial spectrum of density fluctuations in neutralino cold dark matter (CDM) has a sharp cutoff due to two damping mechanisms: collisional damping during the kinetic decoupling of the neutralinos at O(10 MeV) and free streaming after last scat...

We have compared numerical simulations to observations for the nearby (< 40 Mpc) groups of galaxies (Huchra & Geller 1982 and Ramella et al. 2002). The group identification is carried out using a group-finding algorithm developed by Huchra & Geller (1982). Using cosmological N-body simulation code with the ΛCDM cosmology, we show that the dynamical properties of groups of galaxies identified fr...

The problem of the existence of nonzero invariant mass of the graviton can have the fundamental significance. The estimate for the upper bound on the graviton mass (m g < 2 · 10 −62) has been derived in Ref. [1], where the authors used the data on the existence of the gravitational coupling between the galaxy clusters, which is not cut off by the Yukawa potential at least up to distances ∼500 K...

Based on unified theory of electromagnetic interactions and gravitational interactions, the non-relativistic limit of the equation of motion of a charged Dirac particle in gravitational field is studied. From the Schrodinger equation obtained from this non-relativistic limit, we could see that the classical Newtonian gravitational potential appears as a part of the potential in the Schrodinger ...

If the Standard Model is correct, and fundamental fermions exist only in the three generations, then the CKM matrix should be unitary. However, there remain questions over 2+ standard deviations from unitarity in the various data sets, in part from the value of the neutron lifetime. We discuss a simple space-based experiment that, at an orbit height of 500 km above Earth, would measure the kine...

We simulate the future evolution of the observed inhomogeneities in the local universe assuming that the global expansion rate is dominated by a cosmological constant. We find that within two Hubble times (∼ 30 billion years) from the present epoch, large-scale structures will freeze in comoving coordinates and the mass distribution of bound objects will stop evolving. The Local Group will get ...

We show that the isentropic subclass of Buchdahl’s exact solution for a gaseous relativistic star is stable and gravitationally bound for all values of the compactness ratio u[≡ (M/R), where M is the total mass and R is the radius of the configuration in geometrized units] in the range, 0 < u ≤ 0.20, corresponding to the regular behaviour of the solution. This result is in agreement with the ex...

We construct a Galacto-Local Group rotation curve, combining the Galactic rotation curve with a diagram, where galacto-centric radial velocities of outer globular clusters and member galaxies of the Local Group are plotted against their galacto-centric distances. The high-velocity ends of this pseudo rotation curve within a radius R ∼ 150 kpc are well traced by a rotation curve calculated for t...

Recent hydrodynamic simulations of galaxy formation reveal streams of cold (T ∼ 10 K) gas flowing into the centers of dark matter halos as massive as 10M⊙ at redshifts z ∼ 1–3. In this paper we show that if > ∼ 10% of the gravitational binding energy of the gas is radiated away, then the simulated cold flows are spatially extended Lyα sources with luminosities, Lyα line widths, and number densi...

We here propose a two-step model for gamma-ray bursts (GRBs) associated with supernovae. In the first step, the core collapse of a star with mass ≥ 19M⊙ leads to a massive neutron star and a normal supernova, and subsequently hypercritical accretion of the neutron star from the supernova ejecta may give rise to a jet through neutrino annihilation along the stellar rotation axis. However, becaus...