Non-thermal X-ray Emission: An Alternative to Cluster Cooling Flows?

We report the results of experiments aimed at reducing the major problem with cooling flow models of rich cluster X-ray sources: the fact that most of the cooled gas or its products have not been found. Here we show that much of the X-ray emission usually attributed to cooling flows can, in fact, be modeled by a power-law component which is indicative of a source(s) other than thermal bremsstrahlung from the intracluster medium. We find that adequate simultaneous fits to ROSAT PSPCB and ASCA GIS/SIS spectra of the central regions of ten clusters are obtained for two-component models that include a thermal plasma component that is attributable to hot intracluster gas and a power-law component that is likely generated by compact sources and/or extended non-thermal emission. For five of the clusters that purportedly have massive cooling flows, the best-fit models have power-law components that contribute $\sim$ 30 % of the total flux (0.14 - 10.0 keV) within the central 3 arcminutes. Because cooling flow mass deposition rates are inferred from X-ray fluxes, our finding opens the possibility of significantly reducing cooling rates.Comment: 11 pages, 3 figures, emulateapj style. Accepted for publication in Ap

The Australian corporate closet, why it\u27s still so full: a review of incidence rates for sexual orientation discrimination gender identity discrimination in the workplace

The paper reviews the extant Australian literature on sexual orientation (SO) discrimination within the Australian workplace. In the research, there is variation in organisational workplace and a bias towards health and educational sectors as a research setting, which raises some methodological considerations such as poor generalisability to other organisational contexts. The small body of Australian research into SO discrimination encompasses; (i) varied methodological and theoretical approaches, (ii) disparate authors selecting a varied range of aspects of discrimination thus absenting a unifying framework to guide research and lacking as yet seminal authorship providing focus, iii) limited sampling of participants making comparisons difficult and further indicating the absence of a unifying framework with which to focus the research and iv) limited studies exclusively investigating workplace discrimination. In this paper, the Australian literature is presented chronologically, and where possible, it has linked studies together to indicate the commensurate nature of the studies to illustrate the incidence rates of SO discrimination in the Australian labour market as a rationale for GLBTIQ employees remaining in the corporate closet

Homophobia to heterosexism: constructs in need of re-visitation

Although the concept of homophobia has been used extensively in the literature since the early 1960s, researchers have shown growing concern for its relevance in present day research. Additionally, there has been variance in its definition leading to an array of ambiguities resulting in methodological limitations in empirical studies with a disregard for ensuring that definitions used match the focus of study. There have been numerous attempts to locate the construct within a theoretical framework and this has also resulted in weak empirical design. These weaknesses in research on homophobia have resulted in the coining of the construct heterosexism as a more contemporary and more appropriate definition than that of homophobia to indicate anti-gay discrimination. This review considers both terms with regard to their appropriateness and distinction and the utility of the construct heterosexism as it is applied to contemporary research on non-heterosexual communities. It is concluded that homophobia can no longer be framed as a straightforward function of individual psyches or irrational fear and loathing and that heterosexism is more appropriate in defining prejudiced behaviours and their consequences for non-heterosexual communities

The impact of baryonic processes on the two-point correlation functions of galaxies, subhaloes and matter

The observed clustering of galaxies and the cross-correlation of galaxies and mass provide important constraints on both cosmology and models of galaxy formation. Even though the dissipation and feedback processes associated with galaxy formation are thought to affect the distribution of matter, essentially all models used to predict clustering data are based on collisionless simulations. Here, we use large hydrodynamical simulations to investigate how galaxy formation affects the autocorrelation functions of galaxies and subhaloes, as well as their cross-correlation with matter. We show that the changes due to the inclusion of baryons are not limited to small scales and are even present in samples selected by subhalo mass. Samples selected by subhalo mass cluster ~10% more strongly in a baryonic run on scales r > 1Mpc/h, and this difference increases for smaller separations. While the inclusion of baryons boosts the clustering at fixed subhalo mass on all scales, the sign of the effect on the cross-correlation of subhaloes with matter can vary with radius. We show that the large-scale effects are due to the change in subhalo mass caused by the strong feedback associated with galaxy formation and may therefore not affect samples selected by number density. However, on scales r < r_vir significant differences remain after accounting for the change in subhalo mass. We conclude that predictions for galaxy-galaxy and galaxy-mass clustering from models based on collisionless simulations will have errors greater than 10% on sub-Mpc scales, unless the simulation results are modified to correctly account for the effects of baryons on the distributions of mass and satellites.Comment: 15 pages, 9 figures. Replaced to match the version accepted by MNRA

Revisiting the Baryon Fractions of Galaxy Clusters: A Comparison with WMAP 3-year Results

The universal baryonic mass fraction (Omega_b/Omega_m) can be sensitively constrained using X-ray observations of galaxy clusters. In this paper, we compare the baryonic mass fraction inferred from measurements of the cosmic microwave background with the gas mass fractions (f_gas) of a large sample of clusters taken from the recent literature. In systems cooler than 4 keV, f_gas declines as the system temperature decreases. However, in higher temperature systems, f_gas(r500) converges to approx. (0.12 +/- 0.02)(h/0.72)^{-1.5}, where the uncertainty reflects the systematic variations between clusters at r500. This is significantly lower than the maximum-likelihood value of the baryon fraction from the recently released WMAP 3-year results. We investigate possible reasons for this discrepancy, including the effects of radiative cooling and non-gravitational heating, and conclude that the most likely solution is that Omega_m is higher than the best-fit WMAP value (we find Omega_m = 0.36^{+0.11}_{-0.08}), but consistent at the 2-sigma level. Degeneracies within the WMAP data require that sigma_8 must also be greater than the maximum likelihood value for consistency between the data sets.Comment: 8 pages, 3 figures, MNRAS accepte