Professor James Binney FRS

Abstract:

In this study, the role of presence in the imitation of a virtual model was examined. Immersive virtual environment technology (IVET) was used to create photorealistic virtual representations of the self that were depicted eating food in a virtual world. Changes in the virtual environment (via a changing or unchanging body) were incorporated to create variance in perceived subjective presence. Based on previous research, presence was hypothesized to affect the relationship between the environmental manipulations and the behavioral outcome of imitating the avatar's eating behavior. Here we show that presence did indeed affect imitation, but that the effects varied for men and women in accordance with previous research on sex differences in eating behavior. Men who experienced high presence were more likely than low presence men to imitate the virtual model and eat candy, whereas women who experienced high presence were more likely than low presence women to suppress the behavior and not eat candy. © 2009 by the Massachusetts Institute of Technology.

Abstract:

We reanalyse the measurements of parallax, proper motion, and line-of-sight velocity for 18 masers in high mass star-forming regions presented by Reid et al. (2009). We use a likelihood analysis to investigate the distance of the Sun from the Galactic centre, R_0, the rotational speed of the local standard of rest, v_0, and the peculiar velocity of the Sun, vsol, for various models of the rotation curve, and models which allow for a typical peculiar motion of the high mass star-forming regions. We find that these data are best fit by models with non-standard values for vsol or a net peculiar motion of the high mass star-forming regions. We argue that a correction to vsol is much more likely, and that these data support the conclusion of Binney (2009) that V_sol should be revised upwards from 5.2 km/s to 11 km/s. We find that the values of R_0 and v_0 that we determine are heavily dependent on the model we use for the rotation curve, with model-dependent estimates of R_0 ranging from 6.7 \pm 0.5kpc to 8.9 \pm 0.9kpc, and those of v_0 ranging from 200 \pm 20 km/s to 279 \pm 33 km/s. We argue that these data cannot be thought of as implying any particular values of R_0 or v_0. However, we find that v_0/R_0 is better constrained, lying in the range 29.9-31.6 km/s/kpc for all models but one.

Abstract:

Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies.

Abstract:

Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies. © 2009 Macmillan Publishers Limited. All rights reserved.

Abstract:

We describe a technique that finds orbits through the Galaxy that are consistent with measurements of a tidal stream, taking into account the extent that tidal streams do not precisely delineate orbits. We show that if accurate line-of-sight velocities are measured along a well defined stream, the technique recovers the underlying orbit through the Galaxy and predicts the distances and proper motions along the stream to high precision. As the error bars on the location and velocities of the stream grow, the technique is able to find more and more orbits that are consistent with the data and the uncertainties in the predicted distances and proper motions increase. With radial-velocity data along a stream ~40deg long and <0.3deg wide on the sky accurate to ~1 km/s the precisions of the distances and tangential velocities along the stream are 4 percent and 5 km/s, respectively. The technique can be used to diagnose the Galactic potential: if circular-speed curve is actually flat, both a Keplerian potential and Phi(r) proportional to r are readily excluded. Given the correct radial density profile for the dark halo, the halo's mass can be determined to a precision of 5 percent.