A simple analytical model for estimating the fraction (Ωgas) of matter in gaseous form within the collapsed dark matter (DM) haloes is presented. The model is developed using (i) the Press-Schechter formalism to estimate the fraction of baryons in DM haloes, and (ii) the observational estimates of the star formation rate at different redshifts. The prediction for Ωgas from the model is in broad...

A simple analytic model for estimating the fraction (Ωgas) of matter in gaseous form within the collapsed dark matter (DM) haloes is presented. The model is developed using (i) the Press-Schechter formalism to estimate the fraction of baryons in DM haloes, and (ii) the observational estimates of the star formation rate at different redshifts. The prediction for Ωgas from the model is in broad a...

In hierarchical models of gravitational clustering, virialized haloes are biased tracers of the matter distribution. As discussed by Mo & White (1996), this bias is nonlinear and stochastic. They developed a model which allows one to write down analytic expressions for the mean of the bias relation, in the initial Lagrangian, and the evolved, Eulerian, spaces. We provide analytic expressions fo...

Low resistivity in argillaceous sandstone reservoirs may be attributed either to the effect of microporosity, or to specific effects due to clays and/or to conducting minerals. In the frame of a study on pore lining chlorite bearing sandstones, from different hydrocarbon reservoirs, measurements of cation exchange capacities and specific surface areas have been performed, on whole rocks as well...

We use recent observations of the H I mass function to constrain galaxy formation. The data conflict with the standard model where most of the gas in a low-mass dark matter halo is assumed to settle into a disc of cold gas that is depleted by star formation and supernova-driven outflows until the disc becomes gravitationally stable. Assuming a star formation threshold density supported by both ...

Large dynamic range numerical simulations of atomic cooling driven collapse of gas in pre-galactic DM haloes with Tvir ∼ 10000K show that the gas loses 90% and more of its angular momentum before rotational support sets in. In a fraction of these haloes where the metallicity is low and UV radiation suppressesH2 cooling, conditions are thus very favourable for the rapid build-up of massive black...

We study the mass assembly history (MAH) of dark matter haloes. We compare MAHs obtained using (i) merger trees constructed with the extended Press Schechter (EPS) formalism, (ii) numerical simulations, and (iii) the Lagrangian perturbation code PINOCCHIO. We show that the PINOCCHIO MAHs are in excellent agreement with those obtained using numerical simulations, while the EPS formalism predicts...

We investigate the baryon fraction in dark matter haloes formed in non-radiative gasdynamical simulations of the ΛCDM cosmogony. By combining a realisation of the Millennium Simulation (Springel et al.) with a simulation of a smaller volume focussing on dwarf haloes, our study spans five decades in halo mass, from 10 h M⊙ to 10 h M⊙. We find that the baryon fraction within the halo virial radiu...