Astronomy and Space

We present cosmological results from the final galaxy clustering data set of the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey III. Our combined galaxy sample comprises 1.2 million massive galaxies over an effective area of 9329 deg 2 and volume of 18.7 Gpc 3 , divided into three partially overlapping redshift slices centred at effective redshifts 0.38, 0.51 and 0.61. We measure the angular diameter distance D M and Hubble parameter H from the baryon acoustic oscillation (BAO) method, in combination with a cosmic microwave background prior on the sound horizon scale, after applying reconstruction to reduce non-linear effects on the BAO feature. Using the anisotropic clustering of the

Context. In analyses of stellar spectra and colours, and for the analysis of integrated light from galaxies, a homogeneous grid of model atmospheres of late-type stars and corresponding flux spectra is needed.

Context. Measurement of the Galactic neutral atomic hydrogen (H i) column density, N H i , and brightness temperatures, T B , is of high scientific value for a broad range of astrophysical disciplines. In the past two decades, one of the most-used legacy H i datasets has been the Leiden/Argentine/Bonn Survey (LAB).

We have constructed a grid of about 10,000 spherically symmetric and plane-parallel models with the MARCS program, and make it available for public use. Parameter ranges are: Teff=2500 to 8000 K, log g =log(GM/R2)= -1 to 5 (cgs) with various masses and radii, [Me/H]=-5 to +1, with [Alpha/Fe] = 0.0 and 0.4 and different choices of C and N abundances to also represent stars of types R, S and N, and with microturbulence parameters from 1 to 5 km/s. We also list fluxes in approximately 108,000 wavelength points. Underlying assumptions in addition to 1D stratification include hydrostatic equilibrium, MLT convection and LTE. A number of general properties of the models are discussed, in relation to the effects of changing blanketing and sphericity. Models are compared with other available grids and excellent agreement is found with plane-parallel models of Castelli and Kurucz within the overlapping parameter range. Although there are departures from the spherically symmetric NextGen models, the agreement with more recent PHOENIX models is gratifying. The models of the grid show regularities, but some interesting departures from general patterns occur for the coolest models due to the molecular opacities. We have tested rules of thumb concerning effects of blanketing and sphericity and found them to often be astonishingly accurate. Some interesting new phenomena have been discovered, such as the intricate coupling between blanketing and sphericity, and the strong effects of carbon enhancement on metal-poor models. We give further details of models and comparisons with observations in subsequent papers.

A reliable method has been developed for making through-bond electrical contacts to molecules. Current-voltage curves are quantized as integer multiples of one fundamental curve, an observation used to identify single-molecule contacts. The resistance of a single octanedithiol molecule was 900 +/- 50 megohms, based on measurements on more than 1000 single molecules. In contrast, nonbonded contacts to octanethiol monolayers were at least four orders of magnitude more resistive, less reproducible, and had a different voltage dependence, demonstrating that the measurement of intrinsic molecular properties requires chemically bonded contacts.

Abstract The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.

We have performed three-dimensional magnetohydrodynamic numerical simulations of an accretion disk to study the nonlinear development of the magnetorotational instability. We use a disk model that is local in the sense that it incorporates tidal and Coriolis forces but neglects background gradients in pressure and density. For simplicity we omit the vertical component of gravity and employ periodic boundary conditions in the vertical and azimuthal directions, and shearing-periodic boundary conditions in the radial direction. Our numerical method is an implementation of the "method of characteristics-constrained transport" algorithm. Most of the simulations begin with either a purely vertical or purely azimuthal magnetic field. Our major result is that turbulence is initiated and sustained by the magnetic instability. We provide a detailed characterization of the saturated turbulent state. The turbulence is anisotropic in a sense that implies an outward flux of angular momentum. The turbulent energy and angular momentum flux is dominated by magnetic stress rather than Reynolds stress. Most of the energy and angular momentum flux is concentrated at the largest scales. We find that the magnetic energy density in the saturated state is proportional to the product of the size of the simulation box and the initial field strength and is independent of the sound speed.

Proceedings of a workshop held atCrimean Astrophysical Observatory, Crimea, Ukraine14 -16 June 2004Edited byC. Martin Gaskell« Department of Physics & Astronomy, University of NebraskaLincoln, Nebraska, USAIan M. McHardyDepartment of Physics & Astronomy, University of SouthamptonSouthampton, United KingdomBradley M. PetersonAstronomy Department, Ohio State University, Columbus, Ohio, USAandSergey G. SergeevCrimean Astrophysical Observatory, Crimea, Ukraine

We investigate with unprecedented accuracy the correlations between the dynamical mass-to-light ratio M/L and other global observables of E and S0 galaxies. We construct two-integral Jeans and three-integral Schwarzschild dynamical models for a sample of 25 E/S0 galaxies with SAURON integral-field stellar kinematics. We find a tight correlation of the form (M/L)=(3.79+/-0.13)*(sigma/200 km/s)^(0.82+/-0.06) between the dynamical M/L (in the I-band) and the luminosity-weighted second moment (sigma) of the line-of-sight velocity-distribution within Re. The observed rms scatter in M/L for our sample is 17%, while the intrinsic scatter is negligible with respect to the measurement errors. The (M/L)-sigma relation can be included in the remarkable series of tight correlations between sigma and other galaxy global observables. The comparison of the observed correlations with the predictions of the Fundamental Plane (FP), and with simple virial estimates, shows that the `tilt' of the FP of early-type galaxies, is due to a real M/L variation, while structural and orbital non-homology have a negligible effect. The virial mass is a reliable estimator of the mass in the central regions of galaxies. The best-fitting virial relation has the form (M/L)_vir=(4.8+/-0.1)*Re*sigma^2/(L*G). The comparison of the dynamical M/L with the (M/L)_pop inferred from the analysis of the stellar population, indicates that dark matter in early-type galaxies contributes <30% of the total mass inside one Re. (Abridged)

Vector magnetic field observations of the martian crust were acquired by the Mars Global Surveyor (MGS) magnetic field experiment/electron reflectometer (MAG/ER) during the aerobraking and science phasing orbits, at altitudes between approximately 100 and 200 kilometers. Magnetic field sources of multiple scales, strength, and geometry were observed. There is a correlation between the location of the sources and the ancient cratered terrain of the martian highlands. The absence of crustal magnetism near large impact basins such as Hellas and Argyre implies cessation of internal dynamo action during the early Naochian epoch ( approximately 4 billion years ago). Sources with equivalent magnetic moments as large as 1.3 x 10(17) ampere-meter2 in the Terra Sirenum region contribute to the development of an asymmetrical, time-variable obstacle to solar wind flow around Mars.

We re-examine the observed near-infrared properties of T Tauri stars and interpret them with the aid of accretion disk models. Based upon a careful analysis of the dereddened near-infrared colors, we find that T Tauri stars exhibit a surprisingly narrow range in (J-H)/(H-K) and (H-K)/(K-L) color-color diagrams. We find that accretion disk models with a range of accretion rates (10(-8) M<SUB>sun</SUB> yr(-1) &lt; Mdot &lt; 10(-6) M<SUB>sun</SUB> yr(-1) ), inner-disk radii (1-6 R_*), and viewing angles can account for the distribution of intrinsic near-infrared excesses. If the assumptions upon which our models are based are correct, we find that: i) the disk accretion rates needed to explain the observations are consistent with those inferred from optical spectroscopic studies; and ii) inner-disk holes are required in order to explain the range of observed intrinsic near-infrared excesses. Our model results suggest that a given near-IR excess requires a minimum disk accretion rate, though larger accretion rates can be accommodated with specific combinations of inner disk hole size and viewing inclinations. Further, we combine optical veiling measurements, knowledge of stellar SEDs and reddening, in order to estimate infrared photometric flux excesses for our sample of T Tauri stars. Assuming a distribution of mass accretion rates inferred from optical veiling studies, and a random distribution of viewing inclinations, we examine the plausible range of inner-disk hole sizes. The absence of inner-disk holes predicts near-IR excesses larger than those observed. Inner-disk holes exclusively &gt; 8R_* are inconsistent with the observations, whereas hole sizes between 2-6 R_* are well-matched to the data. Finally we examine the impact of our results on attempts to characterize the accretion properties of embedded young star clusters.

We investigate the electronic properties of ultrathin hexagonal boron nitride (h-BN) crystalline layers with different conducting materials (graphite, graphene, and gold) on either side of the barrier layer. The tunnel current depends exponentially on the number of h-BN atomic layers, down to a monolayer thickness. Conductive atomic force microscopy scans across h-BN terraces of different thickness reveal a high level of uniformity in the tunnel current. Our results demonstrate that atomically thin h-BN acts as a defect-free dielectric with a high breakdown field. It offers great potential for applications in tunnel devices and in field-effect transistors with a high carrier density in the conducting channel.

Working in concert, theorists and experimentalists have found promising new ways to get two traditional foes—ferroelectricity and magnetism—to coexist

Results of observations of the sky north of delta = -40 deg in the 21-cm line of atomic hydrogen are reported. The survey covers a velocity range of 654 km/s centered on the Galactic standard of rest, with 5.3-km/s wide filters. Calibration and reduction of the observations are described. The survey is presented as a series of images of the sky, each covering a 10-km/s wide velocity range. This survey is distinguished by its sensitivity to low surface brightness features (TA is approximately equal to 50 mK) and relative freedom from sidelobe contamination. High-velocity clouds are extracted and cataloged automatically. At the resolution of the survey, the lowest H I column density in the sky is 5.7 x 10 exp 19/cm.

This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions. © 2013. The American Astronomical Society. All rights reserved..

An extensively pursued current direction of research in physics aims at the development of practical technologies that exploit the effects of quantum mechanics. As part of this ongoing effort, devices for quantum information processing, secure communication, and high-precision sensing are being implemented with diverse systems, ranging from photons, atoms, and spins to mesoscopic superconducting and nanomechanical structures. Their physical properties make some of these systems better suited than others for specific tasks; thus, photons are well suited for transmitting quantum information, weakly interacting spins can serve as long-lived quantum memories, and superconducting elements can rapidly process information encoded in their quantum states. A central goal of the envisaged quantum technologies is to develop devices that can simultaneously perform several of these tasks, namely, reliably store, process, and transmit quantum information. Hybrid quantum systems composed of different physical components with complementary functionalities may provide precisely such multitasking capabilities. This article reviews some of the driving theoretical ideas and first experimental realizations of hybrid quantum systems and the opportunities and challenges they present and offers a glance at the near- and long-term perspectives of this fascinating and rapidly expanding field.

The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy programme designed to map a set of nested fields totalling ~380deg 2. Fields range in size from 0.01 to ~20deg 2, using the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) (at 250, 350 and 500μm) and the Herschel-Photodetector Array Camera and Spectrometer (PACS) (at 100 and 160μm), with an additional wider component of 270deg 2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the reprocessed optical and ultraviolet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multiwavelength understanding of galaxy formation and evolution. The survey will detect of the order of 100000 galaxies at 5σ in some of the best-studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to facilitate redshift determination, rapidly identify unusual objects and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include the total infrared emission of galaxies, the evolution of the luminosity function, the clustering properties of dusty galaxies and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS.

The available data on nuclear fusion cross sections important to energy generation in the Sun and other hydrogen-burning stars and to solar neutrino production are summarized and critically evaluated. Recommended values and uncertainties are provided for key cross sections, and a recommended spectrum is given for $^{8}\mathrm{B}$ solar neutrinos. Opportunities for further increasing the precision of key rates are also discussed, including new facilities, new experimental techniques, and improvements in theory. This review, which summarizes the conclusions of a workshop held at the Institute for Nuclear Theory, Seattle, in January 2009, is intended as a 10-year update and supplement to 1998, Rev. Mod. Phys. 70, 1265.

Observations have set the first constraints on the epoch of reionization (EoR), corresponding to the formation epoch of the first luminous objects. Studies of Gunn-Peterson (GP) absorption indicate a rapid increase in the neutral fraction of the intergalactic medium (IGM) from x HI &lt; 10 −4 at z ≤ 5.5, to x HI &gt; 10 −3 , perhaps up to 0.1, at z∼6, while the large scale polarization of the cosmic microwave background (CMB) implies a significant ionization fraction extending to higher redshifts, z∼11 ± 3. These results, as well as observations of galaxy populations, suggest that reionization is a process that begins as early as z∼14, and ends with the “percolation” phase at z∼6 to 8. Low luminosity star-forming galaxies are likely the dominant sources of reionizing photons. Future low-frequency radio telescopes will make direct measurements of HI 21-cm emission from the neutral IGM during the EoR, and measurements of secondary CMB temperature anisotropy will provide details of the dynamics of the reionized IGM.

Materials with correlated electrons exhibit some of the most intriguing phenomena in condensed matter physics. A new theoretical framework is now allowing theorists to calculate the electronic structure of these materials, which can exist in a rich variety of phases.