Dark matter cores in the Fornax and Sculptor dwarf galaxies: joining halo assembly and detailed star formation histories

We combine the detailed Star Formation Histories of the Fornax and Sculptor dwarf Spheroidals with the Mass Assembly History of their dark matter (DM) halo progenitors to estimate if the energy deposited by Supernova type II (SNeII) is sufficient to create a substantial DM core. Assuming the efficiency of energy injection of the SNeII into DM particles is $\epsilon_{\rm gc}=0.05$, we find that a single early episode, $z \gtrsim z_{\rm infall}$, that combines the energy of all SNeII due to explode over 0.5 Gyr, is sufficient to create a core of several hundred parsecs in both Sculptor and Fornax. Therefore, our results suggest that it is energetically plausible to form cores in Cold Dark Matter (CDM) halos via early episodic gas outflows triggered by SNeII. Furthermore, based on CDM merger rates and phase-space density considerations, we argue that the probability of a subsequent complete regeneration of the cusp is small for a substantial fraction of dwarf-size haloes.Comment: ApJL accepted versio

The relationship between the need for closure and support for military action against Iraq: moderating effects of national attachment.

A variety of studies suggest that a high need for closure—that is,a desire for knowledge that is clear, stable, and unambiguous as opposed to confusing or uncertain—may be associated with greater hostility toward relevant outgroups. Using international attitudes as the context, the authors examine the hypothesis that the relationship between the need for closure and support for military action against Iraq may be moderated by identification with the national ingroup. Specifically, it is expected that this relationship will be moderated by nationalism (i.e., an aggressive form of identification based on a desire for national dominance)but not patriotism (i.e., a more neutral love of one’s country). The data provided a clear pattern of support for this hypothesis and additional analyses indicated that a high need for closure reduced variability about the use of force among the highly nationalistic but not the highly patrioti

Need for closure and coercion in inter-group conflicts: experimental evidence for the mitigating effect of accessible conflict schemas

Three experimental studies demonstrate that momentarily-accessible conflict-schemas moderate the relationship between need for closure and conflict-strategy preferences, with the relationship between a high need for closure and increased competitiveness reduced to non-significance when a cooperative conflict schema is made salient but strengthened when a hostile one is activated. Study 1 manipulated the accessibility of competitive versus cooperative conflict schemas using different descriptions of a contemporary political conflict, while Studies 2 and 3 manipulated conflict-schema accessibility using primes embedded in an ostensibly-unrelated lexical decision task. Together, the present studies provide a strong pattern of experimental support for the moderating effect of conflict-schema accessibility suggested by earlier correlational studies. The implications for conflict reduction are discussed

Gut bacteria facilitate adaptation to crop rotation in the western corn rootworm

11917-11922Insects are constantly adapting to human-driven landscape changes; however, the roles of their gut microbiota in these processes remain largely unknown. The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) (Coleoptera: Chrysomelidae) is amajor corn pest that has been controlled via annual rotation between corn (Zea mays) and nonhost soybean (Glycine max) in the United States. This practice selected for a 'rotation-resistant' variant (RR-WCR) with reduced ovipositional fidelity to cornfields.When in soybean fields, RRWCRs also exhibit an elevated tolerance of antiherbivory defenses (i.e., cysteine protease inhibitors) expressed in soybean foliage. Here we show that gut bacterial microbiota is an important factor facilitating this corn specialist's (WCR's) physiological adaptation to brief soybean herbivory. Comparisons of gut microbiota between RR- and wild-type WCR (WT-WCR) revealed concomitant shifts in bacterial community structure with host adaptation to soybean diets. Antibiotic suppression of gut bacteria significantly reduced RR-WCR tolerance of soybean herbivory to the level of WT-WCR, whereas WTWCR were unaffected. Our findings demonstrate that gut bacteria help to facilitate rapid adaptation of insects inmanaged ecosystems

A View through Faraday's Fog 2: Parsec Scale Rotation Measures in 40 AGN

Results from a survey of the parsec scale Faraday rotation measure properties for 40 quasars, radio galaxies and BL Lac objects are presented. Core rotation measures for quasars vary from approximately 500 to several thousand radians per meter squared. Quasar jets have rotation measures which are typically 500 radians per meter squared or less. The cores and jets of the BL Lac objects have rotation measures similar to those found in quasar jets. The jets of radio galaxies exhibit a range of rotation measures from a few hundred radians per meter squared to almost 10,000 radians per meter squared for the jet of M87. Radio galaxy cores are generally depolarized, and only one of four radio galaxies (3C-120) has a detectable rotation measure in the core. Several potential identities for the foreground Faraday screen are considered and we believe the most promising candidate for all the AGN types considered is a screen in close proximity to the jet. This constrains the path length to approximately 10 parsecs, and magnetic field strengths of approximately 1 microGauss can account for the observed rotation measures. For 27 out of 34 quasars and BL Lacs their optically thick cores have good agreement to a lambda squared law. This requires the different tau = 1 surfaces to have the same intrinsic polarization angle independent of frequency and distance from the black hole.Comment: Accepted to the Astrophysical Journal: 71 pages, 40 figure

The HgMn Binary Star Phi Herculis: Detection and Properties of the Secondary and Revision of the Elemental Abundances of the Primary

Observations of the Mercury-Manganese star Phi Herculis with the Navy Prototype Optical Interferometer (NPOI) conclusively reveal the previously unseen companion in this single-lined binary system. The NPOI data were used to predict a spectral type of A8V for the secondary star Phi Her B. This prediction was subsequently confirmed by spectroscopic observations obtained at the Dominion Astrophysical Observatory. Phi Her B is rotating at 50 +/-3 km/sec, in contrast to the 8 km/sec lines of Phi Her A. Recognizing the lines from the secondary permits one to separate them from those of the primary. The abundance analysis of Phi Her A shows an abundance pattern similar to those of other HgMn stars with Al being very underabundant and Sc, Cr, Mn, Zn, Ga, Sr, Y, Zr, Ba, Ce, and Hg being very overabundant.Comment: Accepted to ApJ, 45 pages, 11 figure

An interferometric study of the post-AGB binary 89 Herculis I Spatially resolving the continuum circumstellar environment at optical and near-IR wavelengths with the VLTI, NPOI, IOTA, PTI, and the CHARA Array

Binary post-AGB stars are interesting laboratories to study both the evolution of binaries as well as the structure of circumstellar disks. A multiwavelength high angular resolution study of the prototypical object 89 Herculis is performed with the aim of identifying and locating the different emission components seen in the SED. A large interferometric data set, collected over the past decade and covering optical and near-IR wavelengths, is analyzed with simple geometric models. Combining the interferometric constraints with the photometry and the optical spectra, we reassess the energy budget of the post-AGB star and its circumstellar environment. We report the first (direct) detection of a large (35-40%) optical circumstellar flux contribution and spatially resolve its emission region. Given this large amount of reprocessed and/or redistributed optical light, the fitted size of the emission region is rather compact and fits with(in) the inner rim of the circumbinary dust disk. This rim dominates our K band data through thermal emission and is rather compact, emitting significantly already at a radius of twice the orbital separation. We interpret the circumstellar optical flux as due to a scattering process, with the scatterers located in the extremely puffed-up inner rim of the disk and possibly also in a bipolar outflow seen pole-on. A non-LTE gaseous origin in an inner disk cannot be excluded but is considered highly unlikely. This direct detection of a significant amount of circumbinary light at optical wavelengths poses several significant questions regarding our understanding of both post-AGB binaries and the physics in their circumbinary disks. Although the identification of the source of emission/scattering remains inconclusive without further study on this and similar objects, the implications are manifold.Comment: Accepted for publication in A&A, 16 pages, 15 figure