In the ellipsoidal collapse model, the critical density for the collapse of a gravitationally bound object is a function of its mass. In the excursion set formalism, this translates into a moving barrier problem such that the mass function of dark matter haloes is given by the first crossing probability of a random walker across the barrier. In this paper, we study this first crossing probabili...

Enission-line variability data for Seyfert 1 galaxies provide strong evidence for the existence of supermassive black holes in the nuclei of these galaxies, and that the line-emitting gas is moving in the gravitational potential of that black hole. The time-delayed response of the emission lines to continuum variations is used to infer the size of the line-emitting region, which is then combine...

We report on the 2: 00 5 (400 pc) resolution CO (J = 1 ! 0) observations covering the whole length of the bar in the strongly barred late-type spiral galaxy NGC 7479. CO emission is detected only along a dust lane that traverses the whole length of the bar, including the nucleus. The emission is strongest in the nucleus. The distribution of emission is clumpy along the bar outside the nucleus, ...

Observations of damped Lyα systems offer a unique window on the neutral-gas reservoirs that gave rise to galaxies at high redshifts. This review focuses on critical properties such as the H I and metal content of the gas and on independent evidence for star formation. Together, these provide an emerging picture of gravitationally bound objects in which accretion of gas from the IGM replenishes ...

Properties of effective interactions in neutron-rich matter are reflected in the medium’s equation of state (EOS), which is a relationship among several state variables. Spin and isospin asymmetries play an important role in the energy balance and could alter the stability conditions of the nuclear EOS. The EOS has far-reaching consequences for numerous nuclear processes in both the terrestrial...

Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence for a diffuse, hot, thermal plasma at a temperature of ∼ 9. 10 7 K (∼ 8 keV) found by previous surveys to extend over a few hundred parsecs in the Galactic Centre region. This plasma coexists with the usual components of the interstellar medium such as cold molecular clouds and a soft (0.8 keV) component p...

We present VLA H i 21 cm observations of HIJASS J1021 6842, which has been discovered in the direction of the M81 Group. Our synthesis imaging reveals that the H i is distributed over a larger angular extent and velocity range than the single-dish discovery observations. Assuming that HIJASS J1021 6842 is at the distance of the M81 Group, we detect M, of H i distributed over as much as 30 kpc, ...

A population of molecular clouds with a significantly greater scale height than that of Giant Molecular Clouds has been identified by examining maps of the latitude distribution of the CO(1 − 0) emission in the first quadrant of the Galaxy. These clouds are found by identifying emission more than 2.6 times the scale-height away from the galactic midplane (centroid of CO emission) at the tangent...

This talk reviews the constraints imposed by binary-pulsar data on gravity theories, and notably on “scalar-tensor” theories which are the most natural alternatives to general relativity. Because neutron stars have a strong gravitational binding energy, binarypulsar tests are qualitatively different from solar-system experiments: They have the capability of probing models which are indistinguis...

We study the effects of anisotropic pressure on the properties of spherically symmetric, gravitationally bound objects. We consider the full generalrelativistic treatment of this problem and obtain exact solutions for various forms of the equation of state connecting the radial and tangential pressures. It is shown that pressure anisotropy can have significant effects on the structure and prope...