Spatially Extended Low Ionization Emission Regions (LIERs) at z∼0.9z\sim0.9

We present spatially resolved emission diagnostics for eight $z\sim0.9$ galaxies that demonstrate extended low ionization emission-line regions (LIERs) over kpc scales. Eight candidates are selected based on their spatial extent and emission line fluxes from slitless spectroscopic observations with the HST/WFC3 G141 and G800L grisms in the well-studied GOODS survey fields. Five of the candidates (62.5%) are matched to X-ray counterparts in the \textit{Chandra X-Ray Observatory} Deep Fields. We modify the traditional Baldwin-Philips-Terlevich (BPT) emission line diagnostic diagram to use [SII]/(H$\alpha$+[NII]) instead of [NII]/H$\alpha$ to overcome the blending of [NII] and H$\alpha$+[NII] in the low resolution slitless grism spectra. We construct emission line ratio maps and place the individual pixels in the modified BPT. The extended LINER-like emission present in all of our candidates, coupled with X-Ray properties consistent with star-forming galaxies and weak [OIII]$\lambda$5007\AA\ detections, is inconsistent with purely nuclear sources (LINERs) driven by active galactic nuclei. While recent ground-based integral field unit spectroscopic surveys have revealed significant evidence for diffuse LINER-like emission in galaxies within the local universe $(z\sim0.04)$, this work provides the first evidence for the non-AGN origin of LINER-like emission out to high redshifts.Comment: 11 pages, 1 table, 6 figures, accepted for publication in the Astrophysics Journal (ApJ

Modeling the color evolution of luminous red galaxies - improvements with empirical stellar spectra

Predicting the colors of Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS) has been a long-standing problem. The g,r,i colors of LRGs are inconsistent with stellar population models over the redshift range 0.1<z<0.7. The g-r colors in the models are on average redder than the data while the r-i colors in the models are bluer towards low redshift. Beyond redshift 0.4, the predicted r-i color becomes instead too red, while the predicted g-r agrees with the data. We provide a solution to this problem, through a combination of new astrophysics and a fundamental change to the stellar population modeling. We find that the use of the empirical library of Pickles (1998) instead of theoretical spectra modifies the predicted colors exactly in the way suggested by the data. The reason is a lower flux in the empirical libraries, with respect to the theoretical ones, in the wavelength range 5500-6500 AA. The discrepancy increases with decreasing effective temperature independently of gravity. This result has general implications for a variety of studies from globular clusters to high-redshift galaxies. The astrophysical part of our solution regards the composition of the stellar populations of these massive Luminous Red Galaxies. We find that on top of the previous effect one needs to consider a model in which ~3% of the stellar mass is in old metal-poor stars. Other solutions such as substantial blue Horizontal Branch at high metallicity or young stellar populations can be ruled out by the data. Our new model provides a better fit to the g-r and r-i colors of LRGs and gives new insight into the formation histories of these most massive galaxies. Our model will also improve the k- and evolutionary corrections for LRGs which are critical for fully exploiting present and future galaxy surveys.Comment: Submitted to ApJ Letters. High resolution version available at http://www.maraston.eu/Maraston_etal_2008.pd

Numerical Determination of Critical Conditions for Thermal Ignition

The determination of ignition or thermal explosion in an oxidizing porous body of material, as described by a dimensionless reaction-diffusion equation of the form .tu = .2u + .e-1/u over the bounded region O, is critically reexamined from a modern perspective using numerical methodologies. First, the classic stationary model is revisited to establish the proper reference frame for the steady-state solution space, and it is demonstrated how the resulting nonlinear two-point boundary value problem can be reexpressed as an initial value problem for a system of first-order differential equations, which may be readily solved using standard algorithms. Then, the numerical procedure is implemented and thoroughly validated against previous computational results based on sophisticated path-following techniques. Next, the transient nonstationary model is attacked, and the full nonlinear form of the reaction-diffusion equation, including a generalized convective boundary condition, is discretized and expressed as a system of linear algebraic equations. The numerical methodology is implemented as a computer algorithm, and validation computations are carried out as a prelude to a broad-ranging evaluation of the assembly problem and identification of the watershed critical initial temperature conditions for thermal ignition. This numerical methodology is then used as the basis for studying the relationship between the shape of the critical initial temperature distribution and the corresponding spatial moments of its energy content integral and an attempt to forge a fundamental conjecture governing this relation. Finally, the effects of dynamic boundary conditions on the classic storage problem are investigated and the groundwork is laid for the development of an approximate solution methodology based on adaptation of the standard stationary model

Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements

Cosmic shear constrains cosmology by exploiting the apparent alignments of pairs of galaxies due to gravitational lensing by intervening mass clumps. However galaxies may become (intrinsically) aligned with each other, and with nearby mass clumps, during their formation. This effect needs to be disentangled from the cosmic shear signal to place constraints on cosmology. We use the linear intrinsic alignment model as a base and compare it to an alternative model and data. If intrinsic alignments are ignored then the dark energy equation of state is biased by ~50 per cent. We examine how the number of tomographic redshift bins affects uncertainties on cosmological parameters and find that when intrinsic alignments are included two or more times as many bins are required to obtain 80 per cent of the available information. We investigate how the degradation in the dark energy figure of merit depends on the photometric redshift scatter. Previous studies have shown that lensing does not place stringent requirements on the photometric redshift uncertainty, so long as the uncertainty is well known. However, if intrinsic alignments are included the requirements become a factor of three tighter. These results are quite insensitive to the fraction of catastrophic outliers, assuming that this fraction is well known. We show the effect of uncertainties in photometric redshift bias and scatter. Finally we quantify how priors on the intrinsic alignment model would improve dark energy constraints.Comment: 14 pages and 9 figures. Replaced with final version accepted in "Gravitational Lensing" Focus Issue of the New Journal of Physics at http://www.iop.org/EJ/abstract/1367-2630/9/12/E0

Investigating the origins of the CMB-XRB cross correlation

Recently, we presented evidence for a cross-correlation of the WMAP satellite map of the cosmic microwave background (CMB) and the HEAO1 satellite map of the hard X-ray background (XRB) with a dimensionless amplitude of 0.14 +- 0.05 normalized to the product of the rms fluctuations of the CMB and XRB (Boughn & Crittenden, 2004). Such a correlation is expected in a universe dominated by a cosmological constant via the integrated Sachs-Wolfe (ISW) effect and the level of the correlation observed is consistent with that predicted by the currently favored Lambda cold dark matter model of the universe. Since this offers independent confirmation of the cosmological model, it is important to verify the origin of the correlation. Here we explore in detail some possible foreground sources of the correlation. The present evidence all supports an ISW origin.Comment: 8 pages, 7 eps figure

Recommendations of the 2007 Healthy Lifestyle Forum to Help Combat Childhood Obesity

Senator Guy Barnett has held eight Healthy Lifestyle Forums to Help Combat Childhood Obesity since entering the Senate in 2002. The most recent forum, held on 20 June 2007 at Australian Parliament House Canberra, brought together approximately 60 concerned members of health care, academia, industry and public health to develop useful interventions and ideas for fighting childhood obesity. This report details the recommendations of the groups convened. They were asked to consider actions in the key areas of: clinical/health care system monitoring/benchmarking infant and early childhood schools and the wider community, and industry and private sector solutions

Luminous Red Galaxy Clustering at z~0.7 - First Results using AAOmega

We report on the AAT-AAOmega LRG Pilot observing run to establish the feasibility of a large spectroscopic survey using the new AAOmega instrument. We have selected Luminous Red Galaxies (LRGs) using single epoch SDSS riz-photometry to i<20.5 and z<20.2. We have observed in 3 fields including the COSMOS field and the COMBO-17 S11 field, obtaining a sample of ~600 redshift z>=0.5 LRGs. Exposure times varied from 1 - 4 hours to determine the minimum exposure for AAOmega to make an essentially complete LRG redshift survey in average conditions. We show that LRG redshifts to i<20.5 can measured in approximately 1.5hr exposures and present comparisons with 2SLAQ and COMBO-17 (photo-)redshifts. Crucially, the riz selection coupled with the 3-4 times improved AAOmega throughput is shown to extend the LRG mean redshift from z=0.55 for 2SLAQ to z=0.681+/- 0.005 for riz-selected LRGs. This extended range is vital for maximising the S/N for the detection of the baryon acoustic oscillations (BAOs). Furthermore, we show that the amplitude of LRG clustering is s_0 = 9.9+/-0.7 h^-1 Mpc, as high as that seen in the 2SLAQ LRG Survey. Consistent results for the real-space amplitude are found from projected and semi-projected correlation functions. This high clustering amplitude is consistent with a long-lived population whose bias evolves as predicted by a simple ``high-peaks'' model. We conclude that a redshift survey of 360 000 LRGs over 3000deg^2, with an effective volume some 4 times bigger than previously used to detect BAO with LRGs, is possible with AAOmega in 170 nights.Comment: 12 pages, 7 figures, 8 tables, minor changes, matches published versio

Longitudinal changes in respiratory and upper limb function in a pediatric type III spinal muscular atrophy cohort after loss of ambulation

Introduction/Aims: Spinal muscular atrophy (SMA) type III is a relatively mild form of SMA. Few studies have investigated the changes in both respiratory and upper limb function within this population after loss of ambulation. The aim of this study was to assess change in percentage of predicted forced vital capacity (FVC% predicted) and change in the Revised Upper Limb Module (RULM) score in these patients throughout a 24-month period after loss of ambulation. Effect of scoliosis and its surgical correction, disease duration since loss of ambulation, weight, and height were also investigated. / Methods: Retrospective analyses were performed on 24 nonambulant SMA III patients from data collected at two centers in the United Kingdom. / Results: The FVC% predicted score showed a significant progressive deterioration of 17% over the 24-month period. Respiratory deterioration correlated significantly with age, weight, disease duration since loss of ambulation, and spinal correctional surgery. Longitudinal RULM data were available for 16 patients; a significant deterioration was observed with a mean decrease in score of 3 over 24 months. Age correlated negatively with RULM score, as did height and time since loss of ambulation. A significant positive correlation between FVC% predicted and RULM was demonstrated. / Discussion: This study highlights how SMA type III patients have progressive deterioration of respiratory and upper limb function after loss of ambulation. Combining data from these assessments could provide insight into clinical progression, inform clinical trials, and provide assistance in managing disease progression expectations for patients