The Low Quiescent X-Ray Luminosity of the Neutron Star Transient XTE J2123-058

We report on the first X-ray observations of the neutron star soft X-ray transient (SXT) XTE J2123-058 in quiescence, made by Chandra and BeppoSAX, as well as contemporaneous optical observations. In 2002, the Chandra spectrum of XTE J2123-058 is consistent with a power-law model, or the combination of a blackbody plus a power-law, but it is not well-described by a pure blackbody. Using the interstellar column density, the power-law fit gives photon index of 3.1 (+0.7,-0.6) and indicates a 0.3-8 keV unabsorbed luminosity of 9(+4,-3)E31 (d/8.5 kpc)^2 ergs/s (90% confidence errors). Fits with models consisting of thermal plus power-law components indicate that the upper limit on the temperature of a 1.4 solar mass, 10 km radius neutron star with a hydrogen atmosphere is kT_eff < 66 eV, and the upper limit on the bolometric luminosity is L_infinity < 1.4E32 ergs/s, assuming d = 8.5 kpc. Of the neutron star SXTs that exhibit short (< 1 year) outbursts, including Aql X-1, 4U 1608-522, Cen X-4, and SAX J1810.8-2609, the lowest temperatures and luminosities are found for XTE J2123-058 and SAX J1810.8-2609. From the BeppoSAX observation of XTE J2123-058 in 2000, we obtained an upper limit on the 1-10 keV unabsorbed luminosity of 9E32 ergs/s. Although this upper limit allows that the X-ray luminosity may have decreased between 2000 and 2002, that possibility is not supported by our contemporaneous R-band observations, which indicate that the optical flux increased significantly. Motivated by the theory of deep crustal heating by Brown and co-workers, we characterize the outburst histories of the five SXTs. The low quiescent luminosity for XTE J2123-058 is consistent with the theory of deep crustal heating without requiring enhanced neutron star cooling if the outburst recurrence time is >~ 70 years.Comment: 8 pages, accepted by Ap

Communication and Group Perception: Extending the `Saying is Believing' Effect

The saying-is-believing (SIB) effect occurs when tailoring a message to suit an audience influences a communicator's subsequent memories and impressions about the communication topic. Previous studies were restricted to one-person audiences and individuals as the communication topic. The present studies explored the SIB effect with multiple-person audiences and groups as the communication topic. In Study 1, the SIB effect occurred with a 1-person, but not a 3-person, audience. In Study 2, the SIB effect occurred with a 3-person audience when the audience explicitly validated communicators' messages. These findings demonstrate the generalizability of the SIB effect to group contexts, provide further evidence for a shared reality interpretation of this effect, and suggest a potentially important mechanism underlying stereotype development

Wave Mechanics of a Two Wire Atomic Beamsplitter

We consider the problem of an atomic beam propagating quantum mechanically through an atom beam splitter. Casting the problem in an adiabatic representation (in the spirit of the Born-Oppenheimer approximation in molecular physics) sheds light on explicit effects due to non-adiabatic passage of the atoms through the splitter region. We are thus able to probe the fully three dimensional structure of the beam splitter, gathering quantitative information about mode-mixing, splitting ratios,and reflection and transmission probabilities

New X-ray Clusters in the EMSS II: Optical Properties

We present optical images for 9 new clusters of galaxies we have found in a reanalysis of the Einstein IPC images comprising the Extended Medium Sensitivity Survey (EMSS). Based on the presence of a red sequence of galaxies in a color-magnitude (CM) diagram, a redshift is estimated for each cluster. Galaxy overdensities (cluster richnesses) are measured in each field using the B_gc statistic which allows their plausible identification with the X-ray emission. The nature of our X-ray detection algorithm suggests that most of these clusters have low X-ray surface brightness (LSB) compared to the previously known EMSS clusters. We compare the optical and X-ray observations of these clusters with the well-studied Canadian Network for Observational Cosmology (CNOC) subsample of the EMSS, and conclude that the new clusters exhibit a similar range of optical richnesses, X-ray luminosities, and, somewhat surprisingly, galaxy populations as the predominantly rich, relaxed EMSS/CNOC clusters.Comment: Accepted to ApJ, 17 pages, 14 figures, uses emulateapj5.st

Cold collisions of OH and Rb. I: the free collision

We have calculated elastic and state-resolved inelastic cross sections for cold and ultracold collisions in the Rb($^1 S$) + OH($^2 \Pi_{3/2}$) system, including fine-structure and hyperfine effects. We have developed a new set of five potential energy surfaces for Rb-OH($^2 \Pi$) from high-level {\em ab initio} electronic structure calculations, which exhibit conical intersections between covalent and ion-pair states. The surfaces are transformed to a quasidiabatic representation. The collision problem is expanded in a set of channels suitable for handling the system in the presence of electric and/or magnetic fields, although we consider the zero-field limit in this work. Because of the large number of scattering channels involved, we propose and make use of suitable approximations. To account for the hyperfine structure of both collision partners in the short-range region we develop a frame-transformation procedure which includes most of the hyperfine Hamiltonian. Scattering cross sections on the order of $10^{-13}$ cm$^2$ are predicted for temperatures typical of Stark decelerators. We also conclude that spin orientation of the partners is completely disrupted during the collision. Implications for both sympathetic cooling of OH molecules in an environment of ultracold Rb atoms and experimental observability of the collisions are discussed.Comment: 20 pages, 16 figure

Norm violators as threats and opportunities: The many faces of deviance in groups

Group researchers have long been interested in how group members respond to deviance, defined as the violation of prescriptive norms about how members should think, feel, or act. Valuable perspectives on reaction to deviance have been offered by scholars in several disciplines, including social psychology, evolutionary psychology, and sociology. Most of the theoretical and empirical work on reaction to deviance assumes that this behavior has negative consequences for group welfare and hence elicits efforts designed to reduce or eliminate it, including the threat or use of punishment. However, there is increasing interest in the other side of the coin, namely cases in which deviance has positive consequences for group welfare and hence is tolerated or even celebrated. In addition, researchers are also devoting increased attention to the causes of deviance, that is, the reasons why some group members choose to violate prescriptive norms even though doing so may elicit punishment. The papers in this Special Issue, which investigate deviance in a wide range of situations, illustrate cutting-edge work on each of these themes.info:eu-repo/semantics/publishedVersio

An Investigation of Oxygen Reduction Kinetics in LSF Electrodes

The characteristics of solid oxide fuel cell (SOFC) cathodes, prepared by infiltration of La0.8Sr0.2FeO3−δ (LSF) into porous yttria-stabilized zirconia (YSZ) scaffolds, were evaluated by studying the effect of p(O2) and of Al2O3overlayers deposited by Atomic Layer Deposition (ALD) on impedance spectra at 873 and 973 K. The electrode resistance of LSF-YSZ composites calcined at 1123 K was dominated by high-frequency processes that show a relatively weak p(O2) dependence of −0.2 at 973 K. Composites calcined to 1373 K exhibited additional, low-frequency features in their impedance spectra that were more strongly dependent on p(O2), −0.43. These low-frequency processes are due to O2 adsorption limitations caused by the lower surface area of the LSF phase. Decreases in the exposed LSF surface caused by ALD films caused similar changes in the impedance spectra. The ALD overlayers were disrupted by heating to 1073 K and electrode polarization at 873 K. The implications of these results for understanding O2 adsorption limitations on SOFC cathodes are discussed