Impact of Cluster Physics on the Sunyaev-Zel'dovich Power Spectrum

We use an analytic model to investigate the theoretical uncertainty on the thermal Sunyaev-Zel'dovich (SZ) power spectrum due to astrophysical uncertainties in the thermal structure of the intracluster medium. Our model accounts for star formation and energy feedback (from supernovae and active galactic nuclei) as well as radially dependent non-thermal pressure support due to random gas motions, the latter calibrated by recent hydrodynamical simulations. We compare the model against X-ray observations of low redshift clusters, finding excellent agreement with observed pressure profiles. Varying the levels of feedback and non-thermal pressure support can significantly change both the amplitude and shape of the thermal SZ power spectrum. Increasing the feedback suppresses power at small angular scales, shifting the peak of the power spectrum to lower ell. On the other hand, increasing the non-thermal pressure support has the opposite effect, significantly reducing power at large angular scales. In general, including non-thermal pressure at the level measured in simulations has a large effect on the power spectrum, reducing the amplitude by 50% at angular scales of a few arcminutes compared to a model without a non-thermal component. Our results demonstrate that measurements of the shape of the power spectrum can reveal useful information on important physical processes in groups and clusters, especially at high-redshift where there exists little observational data. Comparing with the recent South Pole Telescope measurements of the small-scale cosmic microwave background power spectrum, we find our model reduces the tension between the values of sigma_8 measured from the SZ power spectrum and from cluster abundances.Comment: 15 Pages, 9 Figures, updated to match version accepted by Ap

Disentangling correlated scatter in cluster mass measurements

The challenge of obtaining galaxy cluster masses is increasingly being addressed by multiwavelength measurements. As scatters in measured cluster masses are often sourced by properties of or around the clusters themselves, correlations between mass scatters are frequent and can be significant, with consequences for errors on mass estimates obtained both directly and via stacking. Using a high resolution 250 Mpc/h side N-body simulation, combined with proxies for observational cluster mass measurements, we obtain mass scatter correlations and covariances for 243 individual clusters along ~96 lines of sight each, both separately and together. Many of these scatters are quite large and highly correlated. We use principal component analysis (PCA) to characterize scatter trends and variations between clusters. PCA identifies combinations of scatters, or variations more generally, which are uncorrelated or non-covariant. The PCA combination of mass measurement techniques which dominates the mass scatter is similar for many clusters, and this combination is often present in a large amount when viewing the cluster along its long axis. We also correlate cluster mass scatter, environmental and intrinsic properties, and use PCA to find shared trends between these. For example, if the average measured richness, velocity dispersion and Compton decrement mass for a cluster along many lines of sight are high relative to its true mass, in our simulation the cluster's mass measurement scatters around this average are also high, its sphericity is high, and its triaxiality is low. Our analysis is based upon estimated mass distributions for fixed true mass. Extensions to observational data would require further calibration from numerical simulations, tuned to specific observational survey selection functions and systematics.Comment: 18 pages, 12 figures, final version to appear in MNRAS, helpful changes from referee and others incorporate

Parameterization Effects in the analysis of AMI Sunyaev-Zel'dovich Observations

Most Sunyaev--Zel'dovich (SZ) and X-ray analyses of galaxy clusters try to constrain the cluster total mass and/or gas mass using parameterised models and assumptions of spherical symmetry and hydrostatic equilibrium. By numerically exploring the probability distributions of the cluster parameters given the simulated interferometric SZ data in the context of Bayesian methods, and assuming a beta-model for the electron number density we investigate the capability of this model and analysis to return the simulated cluster input quantities via three rameterisations. In parameterisation I we assume that the T is an input parameter. We find that parameterisation I can hardly constrain the cluster parameters. We then investigate parameterisations II and III in which fg(r200) replaces temperature as a main variable. In parameterisation II we relate M_T(r200) and T assuming hydrostatic equilibrium. We find that parameterisation II can constrain the cluster physical parameters but the temperature estimate is biased low. In parameterisation III, the virial theorem replaces the hydrostatic equilibrium assumption. We find that parameterisation III results in unbiased estimates of the cluster properties. We generate a second simulated cluster using a generalised NFW (GNFW) pressure profile and analyse it with an entropy based model to take into account the temperature gradient in our analysis and improve the cluster gas density distribution. This model also constrains the cluster physical parameters and the results show a radial decline in the gas temperature as expected. The mean cluster total mass estimates are also within 1 sigma from the simulated cluster true values. However, we find that for at least interferometric SZ analysis in practice at the present time, there is no differences in the AMI visibilities between the two models. This may of course change as the instruments improve.Comment: 19 pages, 13 tables, 24 figure

The potential of palladacycles: more than just precatalysts

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Safety and efficacy of inactivated varicella zoster virus vaccine in immunocompromised patients with malignancies: a two-arm, randomised, double-blind, phase 3 trial

Background Patients who are immunocompromised because of malignancy have an increased risk of herpes zoster and herpes zoster-related complications. We aimed to investigate the efficacy and safety of an inactivated varicella zoster virus (VZV) vaccine for herpes zoster prevention in patients with solid tumour or haematological malignancies.Methods This phase 3, two-ann, randomised, double-blind, placebo-controlled, inulticentre trial with an adaptive design was done in 329 centres across 40 countries. The trial included adult patients with solid tumour malignancies receiving chemotherapy and those with haematological malignancies, either receiving or not receiving chemotherapy. Patients were randomly assigned (1:1) to receive four doses of VZV vaccine inactivated by v irradiation or placebo approximately 30 days apart. The patients, investigators, trial site staff, clinical adjudication committee, and sponsor's clinical and laboratory personnel were masked to the group assignment. The primary efficacy endpoint was herpes zoster incidence in patients with solid tumour malignancies receiving chemotherapy, which was assessed in the modified intention-to-treat population (defined as all randomly assigned patients who received at least one dose of inactivated VZV vaccine or placebo). The primary safety endpoint was serious adverse events up to 28 days after the fourth dose in patients with solid tumour malignancies receiving chemotherapy. Safety endpoints were assessed in all patients who received at least one dose of inactivated VZV vaccine or placebo and had follow-up data. This trial is registered (NCT01254630 and EudraCT 2010-023156-89).Findings Between June 27, 2011, and April 11,2017,5286 patients were randomly assigned to receive VZV vaccine inactivated by gamma irradiation (n=2637) or placebo (n=2649). The haematological malignancy arm was terminated early because of evidence of futility at a planned interim analysis; therefore, all prespecified haematological malignancy endpoints were deemed exploratory. In patients with solid tumour malignancies in the modified intention-to-treat population, confirmed herpes zoster occurred in 22 of 1328 (6.7 per 1000 person-years) VZV vaccine recipients and in 61 of 1350 (18.5 per 1000 person-years) placebo recipients. Estimated vaccine efficacy against herpes zoster in patients with solid tumour malignancies was 63.6% (97.5% CI 36.4 to 79.1), meeting the prespecified success criterion. In patients with solid tumour malignancies, serious adverse events were similar in frequency across treatment groups, occurring in 298 (22.5%) of 1322 patients who received the vaccine and in 283 (21.0%) of 1346 patients who received placebo (risk difference 1.5%, 95% CI -1.7 to 4.6). Vaccine-related serious adverse events were less than 1% in each treatment group. Vaccine-related injection-site reactions were more common in the vaccine group than in the placebo group. In the haematological malignancy group, VZV vaccine was well tolerated and estimated vaccine efficacy against herpes zoster was 16.8% (95% CI -17.8 to 41.3).Interpretation The inactivated VZV vaccine was well tolerated and efficacious for herpes zoster prevention in patients with solid tumour malignancies receiving chemotherapy, but was not efficacious for herpes zoster prevention in patients with haematological malignancies. Copyright (C) 2019 Elsevier Ltd. All rights reserved