Understanding the Nature of the Ultra-Steep Spectrum Diffuse Radio Source in the Galaxy Cluster Abell 272

Ultra-steep spectrum (USS) radio sources with complex filamentary morphologies are a poorly understood subclass of diffuse radio source found in galaxy clusters. They are characterised by power law spectra with spectral indices less than -1.5, and are typically located in merging clusters. We present X-ray and radio observations of the galaxy cluster A272, containing a USS diffuse radio source. The system is an ongoing major cluster merger with an extended region of bright X-ray emission south of the core. Surface brightness analysis yields a $3\sigma$ detection of a merger shock front in this region. We obtain shock Mach numbers $M_\rho = 1.20 \pm 0.09$ and $M_T = 1.7 \pm 0.3$ from the density and temperature jumps, respectively. Optical data reveals that the system is a merger between a northern cool core cluster and a southern non-cool core cluster. We find that the USS source, with spectral index $\alpha^{\text{74 MHz}}_{\text{1.4 GHz}} = -1.9 \pm 0.1$, is located in the bright southern region. Radio observations show that the source has a double-lobed structure with complex filaments, and is centred on the brightest cluster galaxy of the southern subcluster. We provide two suggestions for the origin of this source; the first posits the source as an AGN relic that has been re-energised by the passing of a merger shock front, while the second interprets the complex structure as the result of two overlapping AGN radio outbursts. We also present constraints on the inverse Compton emission at the location of the source.Comment: 14 pages, 16 figures, submitted to MNRA

Strong interaction effects in high-Z K- atoms

A systematic experimental study of strong interaction shifts, widths, and yields from high-Z kaonic atoms is reported. Strong interaction effects for the K-(8→7) transition were measured in U, Pb, and W, and the K-(7→6) transition in W was also observed. This is the first observation of two measurably broadened and shifted kaonic transitions in a single target and thus permitted the width of the upper state to be determined directly, rather than being inferred from yield data. The results are compared with optical-model calculations

Wealth in Britain: A Lifecycle Perspective

Summary: The distribution of wealth in Britain is extremely unequal: more so than the distribution of income. Yet, most recent research into poverty and inequality focuses on income as a measure of well-being: little is known about inequalities in wealth and assets such as financial savings, pensions and property. This book analyses the distribution of wealth across different groups throughout the UK. Levels of wealth vary across different age-groups, and the book focuses on the role of the lifecycle in explaining differences in levels of assets. It explores the factors which influence the accumulation and the running down of assets, examines people’s knowledge about the different ways of accumulating wealth, and looks at why different people build up a wealth base in different ways - and with varying degrees of success. The book is based on a literature review; analysis of the data obtained from the government’s Family Resources Survey; and follow-up interviews with 40 families at different life-cycle stages. It will be useful reading for all researchers, academics, policy-makers and pressure groups involved in economics, welfare and benefits, fiscal policy and inequality in Britain