Galaxy size trends as a consequence of cosmology

We show that recently documented trends in galaxy sizes with mass and redshift can be understood in terms of the influence of underlying cosmic evolution; a holistic view which is complimentary to interpretations involving the accumulation of discreet evolutionary processes acting on individual objects. Using standard cosmology theory, supported with results from the Millennium simulations, we derive expected size trends for collapsed cosmic structures, emphasising the important distinction between these trends and the assembly paths of individual regions. We then argue that the observed variation in the stellar mass content of these structures can be understood to first order in terms of natural limitations of cooling and feedback. But whilst these relative masses vary by orders of magnitude, galaxy and host radii have been found to correlate linearly. We explain how these two aspects will lead to galaxy sizes that closely follow observed trends and their evolution, comparing directly with the COSMOS and SDSS surveys. Thus we conclude that the observed minimum radius for galaxies, the evolving trend in size as a function of mass for intermediate systems, and the observed increase in the sizes of massive galaxies, may all be considered an emergent consequence of the cosmic expansion.Comment: 14 pages, 13 figures. Accepted by MNRA

The role of environment in the morphological transformation of galaxies in 9 intermediate redshift clusters

[abridged] We analyze a sample of 9 massive clusters at 0.4<z<0.6 observed with MegaCam in 4 photometric bands (g,r,i,z) from the core to a radius of 5 Mpc (~4000 galaxies). Galaxy cluster candidates are selected using photometric redshifts computed with HyperZ. Morphologies are estimated with galSVM in two broad morphological types (early-type and late-type). We examine the morphological composition of the red-sequence and the blue-cloud and study the relations between galaxies and their environment through the morphology-density relations (T-Sigma) and the morphology-radius relation (T-R) in a mass limited sample (log(M/Msol)>9.5). We find that the red sequence is already in place at z~0.5 and it is mainly composed of very massive (log(M/Msol)>11.3) early-type galaxies. These massive galaxies seem to be already formed when they enter the cluster, probably in infalling groups, since the fraction remains constant with the cluster radius. Their presence in the cluster center could be explained by a segregation effect reflecting an early assembly history. Any evolution that takes place in the galaxy cluster population occurs therefore at lower masses (10.3<log(M/Msol)<11.3). For these galaxies, the evolution, is mainly driven by galaxy-galaxy interactions in the outskirts as revealed by the T-Sigma relation. Finally, the majority of less massive galaxies (9.5<log(M/Msol)<10.3) are late-type galaxies at all locations, suggesting that they have not started the morphological transformation yet even if this low mass bin might be affected by incompleteness.Comment: A&A in pres

A robust morphological classification of high-redshift galaxies using support vector machines on seeing limited images. I Method description

We present a new non-parametric method to quantify morphologies of galaxies based on a particular family of learning machines called support vector machines. The method, that can be seen as a generalization of the classical CAS classification but with an unlimited number of dimensions and non-linear boundaries between decision regions, is fully automated and thus particularly well adapted to large cosmological surveys. The source code is available for download at http://www.lesia.obspm.fr/~huertas/galsvm.html To test the method, we use a seeing limited near-infrared ($K_s$ band, $2,16\mu m$) sample observed with WIRCam at CFHT at a median redshift of $z\sim0.8$. The machine is trained with a simulated sample built from a local visually classified sample from the SDSS chosen in the high-redshift sample's rest-frame (i band, $0.77\mu m$) and artificially redshifted to match the observing conditions. We use a 12-dimensional volume, including 5 morphological parameters and other caracteristics of galaxies such as luminosity and redshift. We show that a qualitative separation in two main morphological types (late type and early type) can be obtained with an error lower than 20% up to the completeness limit of the sample ($KAB\sim 22$) which is more than 2 times better that what would be obtained with a classical C/A classification on the same sample and indeed comparable to space data. The method is optimized to solve a specific problem, offering an objective and automated estimate of errors that enables a straightforward comparison with other surveys.Comment: 11 pages, 7 figures, 3 tables. Submitted to A&A. High resolution images are available on reques

Proximity effect-assisted absorption of spin currents in superconductors

The injection of pure spin current into superconductors by the dynamics of a ferromagnetic contact is studied theoretically. Taking into account suppression of the order parameter at the interfaces (inverse proximity effect) and the energy-dependence of spin-flip scattering, we determine the temperature-dependent ferromagnetic resonance linewidth broadening. Our results agree with recent experiments in Nb|permalloy bilayers [C. Bell et al., arXiv:cond-mat/0702461].Comment: 4 page

Volatility transmission along the money market yield curve

In this paper we look to model the volatility of money market interest rates -and the transmission of volatility- along the money market yield curve in four countries: the UK, Germany, France and Spain. We use a conditional variance specification which is based on Nelson's Exponential ARCH. We find a significant volatility transmission effect from overnight to longer term money markets for France, Spain and the UK. We also find that, in our small cross section of countries, those with lower (higher) reserve requirements tend to have higher (lower) interbank interest rate volatility. However, reserve requirements generate a perverse seasonal effect: at the end of the maintenance period, both the level of the overnight interest rate volatility and the magnitude of the transmission effect to the rest of the yield curve are higher. References.(jah)(agh)(frl)(jha

A remarkable new butterfly species from western Amazonia (Lepidoptera, Nymphalidae, Satyrinae)

A distinctive new species of butterfly in the subtribe Euptychiina (Nymphalidae: Satyrinae), which is widespread throughout the upper Amazon in Colombia, Ecuador and Peru, is here described. The species is provisionally placed in the genus Magneuptychia Forster, 1964, although this is likely to change as the higher level taxonomy of Euptychiina is resolved and the genus is reviewed in detail.Authorisation has been given for this article to be loaded into the NHM repository (email A. Quevedo, Executive Director of ProAves, 17.1.2017). The attached file is the published version

A study of the leaf cuticles from carboniferous deposits of North America

RESUMENInvestigación sobre cutículas de hojas de los yacimientos carboníferos de Norte América. Este trabajo es parte de un estudio presentado como tesis de grado de la Universidad de Washington, Saint Louis, Mo.. U.S.A. (1956), en el que se estudia la anatomía interna foliar en mancomún con los caracteres cuticulares e indirectamente se hace notar la importancia de los fósiles descritos como ayuda para los estudios estratigráficos. Se empleó un método en cierto modo original para aislar y esclarecer las muestras de cutículas que juzgamos ser de notable utilidad para los paleobotánicos que realizan estudios similares. Se describen en él dos CORDAITALES: Cordaites Kansanus Huertas sp. nov. y C. pyramidalis Huertas sp. nov. y dos FILICALES: Neuropteris reflexa Huertas sp. nov. y Neuropteris siphonopilosa Huertas sp. nov. Muy pocos estudios se han realizado sobre el particular. De ellos se hace un recuento en la sección histórica. En la taxonomía la descripción se ha hecho de propósito quizá muy minuciosa, a fin de relievar la riqueza de los caracteres estables y justos que acreditan la clasificación de especies nuevas. Finalmente se agradece muy sinceramente al Presidente de tesis, decano doctor Henry N. Andrews y a todos los que en una u otra forma cooperaron en el feliz éxito de la presente investigación paleobotánica

Un nuevo genero y especie fósiles de las lecitidáceas

Numero muy limitado de ejemplares fósiles han sido hallados, referibles a la familia intertropical de las Lecitidáceas, Se han descrito los siguientes géneros y especies críticos: Lecythidoanthus kugleri E. W. Berry, 1924 (flor), Mioceno; Trinidad, Indias Británicas Occidentales:  Lecythidophyllum couratariodes E. W. Berry, 1923 (hoja), Mioceno; Palomares, Oaxaca, México: Lecythioxylon brasiliense Milanez, 1935 (madera), Cretáceo Superior, Brasil. Dos descripciones más: Couropita ovata Hollick and amp; Berry, 1924 (hoja), Plioceno, Bahía, Brasil, y Couropita santanderensis Berry, 1936 (hoja), Mioceno, Santander del Sur, Colombia, no están insertas por Andrews (1955) en su índice de Géneros de Plantas Fósiles

Sertum florulae fossilis villae de leiva

El estudio de la flora fósil de Villa de Leiva despierta gran interés paleobotánico y en la presente entrega se describen tres importantes estróbilos de Coníferas. A medida que avanzan las exploraciones y la pormenorizada identificación de los ejemplares fósiles, se va esclareciendo, una visión cada vez más diáfana de la vegetación en Colombia del Cretáceo Inferior y más concretamente del Aptiano Superior. Con ello, es obvio, se avizora el paisaje vegetal y se amplia el conocimiento de las zonas continentales existentes en dicho periodo. Notoria diversidad de especies, a juzgar por los órganos vegetales registrados: conos, rámulos, hojas, grandes brácteas, semillas y troncos, comprueba la lozanía de los bosques cretáceos poblados por una dominancia de Gimnospermas, con caracteres tan patentes y lúcidos que no hacen gravosa ni una aproximada ubicación taxonómica, ni la reconstrucción de su posible habito y posición real en el conjunto del paisaje

On differential equations associated with perturbations of orthogonal polynomials on the unit circle

In this contribution, we propose an algorithm to compute holonomic second-order differential equations satisfied by some families of orthogonal polynomials. Such algorithm is based in three properties that orthogonal polynomials satisfy: a recurrence relation, a structure formula, and a connection formula. This approach is used to obtain second-order differential equations whose solutions are orthogonal polynomials associated with some spectral transformations of a measure on the unit circle, as well as orthogonal polynomials associated with coherent pairs of measures on the unit circle.Comunidad de MadridUniversidad de Alcal