LADUMA: looking at the distant universe with the MeerKAT array

The cosmic evolution of galaxies’ neutral atomic gas content is a major science driver for the Square Kilometre Array (SKA), as well as for its South African (MeerKAT) and Australian (ASKAP) precursors. Among the H I large survey programs (LSPs) planned for ASKAP and MeerKAT, the deepest and narrowest tier of the “wedding cake” will be defined by the combined L-band+UHF-band Looking At the Distant Universe with the MeerKAT Array (LADUMA) survey, which will probe H I in emission within a single “cosmic vuvuzela” that extends to z = 1.4, when the universe was only a third of its present age. Through a combination of individual and stacked detections (the latter relying on extensive multi-wavelength studies of the survey’s target field), LADUMA will study the redshift evolution of the baryonic Tully–Fisher relation and the cosmic H I density, the variation of the H I mass function with redshift and environment, and the connection between H I content and galaxies’ stellar properties (mass, age, etc.). The survey will also build a sample of OH megamaser detections that can be used to trace the cosmic merger history. This proceedings contribution provides a brief introduction to the survey, its scientific aims, and its technical implementation, deferring a more complete discussion for a future article after the implications of a recent review of MeerKAT LSP project plans are fully worked out

The environmental dependence of neutral hydrogen in the GIMIC simulations

We use the Galaxies-Intergalactic Medium Interaction Calculation (GIMIC) cosmological hydrodynamic simulation at z = 0 to study the distribution and environmental dependence of neutral hydrogen (H I) gas in the outskirts of simulated galaxies. This gas can currently be probed directly in, for example, Lyα absorption via the observation of background quasars. Radio facilities, such as the Square Kilometre Array, will provide a complementary probe of the diffuse H I in emission and will constrain the physics underpinning the complex interplay between accretion and feedback mechanisms which affect the intergalactic medium. We extract a sample of 488 galaxies from a resimulation of the average cosmic density GIMIC region. We estimate the neutral hydrogen content of these galaxies and the surrounding intergalactic medium within which they reside. We investigate the average H I radial profiles by stacking the individual profiles according to both mass and environment. We find high H I column densities at large impact parameters in group environments and markedly lower H I densities for non-group galaxies. We suggest that these results likely arise from the combined effects of ram pressure stripping and tidal interactions present in group environments

Towards a design tool for visualizing the functional demand placed on older adults by everyday living tasks

This paper discusses the development of a design tool using data calculated from the biomechanical functional demand on joints in older adults during activities of daily living, portrayed using a visual 'traffic-light' system. Whole body movements of 84 older adults were analysed using a 3D motion capture system and reaction forces were measured by force platforms, and translated into a 3D software model. Although originally intended as a tool for designers, the early evaluation of this method of visualizing the data suggests that it may be of value across those involved in the professional care of older adults