Multi-Phenomena Modeling of the New Bullet Cluster, ZwCl008.8+52, using N-body/hydrodynamical Simulations

We use hydrodynamical/N-body simulations to interpret the newly discovered Bullet-cluster-like merging cluster, ZwCl 0008.8+5215 (ZwCl 0008 hereafter), where a dramatic collision is apparent from multi-wavelength observations. We have been able to find a self-consistent solution for the radio, X-ray, and lensing phenomena by projecting an off-axis, binary cluster encounter viewed just after first core passage. A pair radio relics traces well the leading and trailing shock fronts that our simulation predict, providing constraints on the collision parameters. We can also account for the observed distinctive comet-like X-ray morphology and the positions of the X-ray peaks relative to the two lensing mass centroids and the two shock front locations. Relative to the Bullet cluster, the total mass is about 70% lower, ($1.2\pm0.1) \times 10^{15}$ Msun, with a correspondingly lower infall velocity, $1800\pm300$ km/s, and an impact parameter of $400\pm100$ kpc. As a result, the gas component of the infalling cluster is not trailing significantly behind the associated dark matter as in the case of the Bullet cluster. The degree of agreement we find between all the observables provides strong evidence that dark matter is effectively collisionless on large scales calling into question other claims and theories that advocate modified gravity.Comment: 9 pages, 3 figures, and 1 table, submitted to the Astrophysical Journal for publicationon on December 18. Coments are welcom

Determining Tangential Peculiar Velocities of Clusters of Galaxies using Gravitational Lensing

We propose two new methods for measuring tangential peculiar velocities of rich clusters of galaxies. Our first method is based on weak gravitational lensing and takes advantage of the differing images of background galaxies caused by moving and stationary gravitational potentials. Our second method is based on measuring relative frequency shifts between multiple images of a single strongly lensed background galaxy. We illustrate this method using the example of galaxy cluster CL 0024+1654.Comment: LateX, 4 pages, 2 figures, accepted for publication in Part 1 of The Astrophysical Journa

Functional compounds of einkorn and emmer genotypes

Three einkorn and two emmer genotypes were analysed for concentration of microelements (Fe, Zn and Se) and lipid soluble antioxidants (α-tocopherol, α-tocotrienol and β-carotene). A diversity was observed in micronutrient content, but most of the genotypes have significantly higher trace element and antioxidant contents than the control wheat variety. The emmer genotypes contain lower Fe and β-carotene concentration than einkorn genotypes. The einkorn genotypes have significant higher antioxidant content than the wheat control. On average einkorn has more than three times more β-carotene than the wheat variety. Our results are useful for species/variety choice in functional food production not only for organic but also for conventional farmers, who have/want to operate under low input conditions, especially in Central Europe

Free-form lensing implications for the collision of dark matter and gas in the frontier fields cluster MACS J0416.1-2403

We present a free-form mass reconstruction of the massive lensing cluster MACS J0416.1-2403 using the latest Hubble Frontier Fields data. Our free-form method finds that the extended lensing pattern is generated by two elongated, closely projected clusters of similar mass. Our lens model identifies new lensed images with which we improve the accuracy of the dark matter distribution. We find that the bimodal mass distribution is nearly coincident with the bimodal X-ray emission, but with the two dark matter peaks lying closer together than the centroids of the X-ray emission. We can reproduce this behaviour with our hydrodynamical model, concluding that the clusters are significantly deflected around each other with the plane of the collision lying close to the line of sight. The projected mass profiles of both subclusters are well constrained in the region 30-165 kpc because of the many interior lensed images, leading to surprisingly flat mass profiles of both components at distances 30-100 kpc from the centre, in agreement with recent simulations of self-interacting dark matter. Using N-body simulations, we discuss the extent to which this may be generated by projection effects in our model as the cores graze each other. The relative velocity between the two cores is estimated to be about 1200 km s-1 and mostly along the line of sight so that our simulation is consistent with the relative redshift difference between the two cD galaxies (δz ≈ 0.04).JMD acknowledges support of the consolider project CAD2010-00064 and AYA2012-39475-C02-01 funded by the Ministerio de Economia y Competitividad.Peer Reviewe

A Comparison and Joint Analysis of Sunyaev-Zel'dovich Effect Measurements from Planck and Bolocam for a set of 47 Massive Galaxy Clusters

We measure the SZ signal toward a set of 47 clusters with a median mass of $9.5 \times 10^{14}$ M$_{\odot}$ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius $\theta_{\textrm{s}}$, we find consistency between the integrated SZ signal, $Y_{\textrm{5R500}}$, derived from Bolocam and Planck based on gNFW model fits using A10 shape parameters, with an average ratio of $1.069 \pm 0.030$ (allowing for the $\simeq 5$% Bolocam flux calibration uncertainty). We also perform a joint fit to the Bolocam and Planck data using a modified A10 model with the outer logarithmic slope $\beta$ allowed to vary, finding $\beta = 6.13 \pm 0.16 \pm 0.76$ (measurement error followed by intrinsic scatter). In addition, we find that the value of $\beta$ scales with mass and redshift according to $\beta \propto M^{0.077 \pm 0.026} \times (1+z)^{-0.06 \pm 0.09}$. This mass scaling is in good agreement with recent simulations. We do not observe the strong trend of $\beta$ with redshift seen in simulations, though we conclude that this is most likely due to our sample selection. Finally, we use Bolocam measurements of $Y_{500}$ to test the accuracy of the Planck completeness estimate. We find consistency, with the actual number of Planck detections falling approximately $1 \sigma$ below the expectation from Bolocam. We translate this small difference into a constraint on the the effective mass bias for the Planck cluster cosmology results, with $(1-b) = 0.93 \pm 0.06$.Comment: Updated to include one additional co-author. Also some minor changes to the text based on initial feedbac

Testing hydrostatic equilibrium in galaxy cluster MS 2137

We test the assumption of strict hydrostatic equilibrium in galaxy cluster MS2137.3-2353 (MS 2137) using the latest CHANDRA X-ray observations and results from a combined strong and weak lensing analysis based on optical observations. We deproject the two-dimensional X-ray surface brightness and mass surface density maps assuming spherical and spheroidal dark matter distributions. We find a significant, 40%-50%, contribution from non-thermal pressure in the core assuming a spherical model. This non-thermal pressure support is similar to what was found by Molnar et al. (2010) using a sample of massive relaxed clusters drawn from high resolution cosmological simulations. We have studied hydrostatic equilibrium in MS 2137 under the assumption of elliptical cluster geometry adopting prolate models for the dark matter density distribution with different axis ratios. Our results suggest that the main effect of ellipticity (compared to spherical models) is to decrease the non-thermal pressure support required for equilibrium at all radii without changing the distribution qualitatively. We find that a prolate model with an axis ratio of 1.25 (axis in the line of sight over perpendicular to it) provides a physically acceptable model implying that MS 2137 is close to hydrostatic equilibrium at about 0.04-0.15 Rvir and have an about 25% contribution from non-thermal pressure at the center. Our results provide further evidence that there is a significant contribution from non-thermal pressure in the core region of even relaxed clusters, i.e., the assumption of hydrostatic equilibrium is not valid in this region, independently of the assumed shape of the cluster.Comment: 11 pages, 4 figures, accepted for publication in Ap