Chandra Measurements of a Complete Sample of X-ray Luminous Galaxy Clusters: The Luminosity-Mass Relation

We present the results of work involving a statistically complete sample of 34 galaxy clusters, in the redshift range 0.15$\le$z$\le$0.3 observed with $Chandra$. We investigate the luminosity-mass ($LM$) relation for the cluster sample, with the masses obtained via a full hydrostatic mass analysis. We utilise a method to fully account for selection biases when modeling the $LM$ relation, and find that the $LM$ relation is significantly different than the relation modelled when not account for selection effects. We find that the luminosity of our clusters is 2.2$\pm$0.4 times higher (when accounting for selection effects) than the average for a given mass, its mass is 30% lower than the population average for a given luminosity. Equivalently, using the $LM$ relation measured from this sample without correcting for selection biases would lead to the underestimation by 40% of the average mass of a cluster with a given luminosity. Comparing the hydrostatic masses to mass estimates determined from the $Y_{X}$ parameter, we find that they are entirely consistent, irrespective of the dynamical state of the cluster.Comment: 31 pages, 43 figures, accepted for publication in MNRA

Sunyaev-Zel'dovich-measured Pressure Profiles from the Bolocam X-Ray/SZ Galaxy Cluster Sample

We describe Sunyaev-Zel'dovich (SZ) effect measurements and analysis of the intracluster medium (ICM) pressure profiles of a set of 45 massive galaxy clusters imaged using Bolocam at the Caltech Submillimeter Observatory. We deproject the average pressure profile of our sample into 13 logarithmically spaced radial bins between 0.07R_(500) and 3.5R_(500), and we find that a generalized Navarro, Frenk, and White (gNFW) profile describes our data with sufficient goodness-of-fit and best-fit parameters (C_(500), α, β, γ, P_0 = 1.18, 0.86, 3.67, 0.67, 4.29). We use X-ray data to define cool-core and disturbed subsamples of clusters, and we constrain the average pressure profiles of each of these subsamples. We find that, given the precision of our data, the average pressure profiles of disturbed and cool-core clusters are consistent with one another at R≳ 0.15R_(500), with cool-core systems showing indications of higher pressure at R≾ 0.15R_(500). In addition, for the first time, we place simultaneous constraints on the mass scaling of cluster pressure profiles, their ensemble mean profile, and their radius-dependent intrinsic scatter between 0.1R_(500) and 2.0R_(500). The scatter among profiles is minimized at radii between ≃ 0.2R_(500) and ≃ 0.5R_(500), with a value of ≃ 20%. These results for the intrinsic scatter are largely consistent with previous analyses, most of which have relied heavily on X-ray derived pressures of clusters at significantly lower masses and redshifts compared to our sample. Therefore, our data provide further evidence that cluster pressure profiles are largely universal with scatter of ≃ 20%-40% about the universal profile over a wide range of masses and redshifts

An experimental and kinetic modelling study of pyrolysis and combustion of acetone-butanol-ethanol (abe) mixtures

Bio-butantol is being studied extensively as alternative to conventional fuels due to its propensity of decreasing soot formation and improving the octane number of gasoline, resulting in renewed interest in the the acetone-butanol-ethanol (ABE) fermentation process and combustion of mixtures of acetone, butanol and ethanol. Therefore in this work a detailed mechanism for the pyrolysis and oxidation of ABE is presented containing ∼200 species and ∼6000 reactions. The mechanism is validated against newly acquired pyrolysis data. Laminar flame speeds computations of alcohols and ABE complement the detailed comparisons of the pyrolysis data and allow to further validate the combustion behaviour of bio-butanol