The role of stellar radial motions in shaping galaxy surface brightness profiles

Aims. The physics driving features such as breaks observed in galaxy surface brightness (SB) profiles remains contentious. Here, we assess the importance of stellar radial motions in shaping their characteristics. Methods. We use the simulated Milky Way-mass cosmological discs from the Ramses Disc Environment Study (RaDES) to characterise the radial redistribution of stars in galaxies displaying type-I (pure exponentials), II (downbending), and III (upbending) SB profiles. We compare radial profiles of the mass fractions and the velocity dispersions of different sub-populations of stars according to their birth and current location. Results. Radial redistribution of stars is important in all galaxies regardless of their light profiles. Type-II breaks seem to be a consequence of the combined effects of outward-moving and accreted stars. The former produce shallower inner profiles (lack of stars in the inner disc) and accumulate material around the break radius and beyond, strengthening the break; the latter can weaken or even convert the break into a pure exponential. Further accretion from satellites can concentrate material in the outermost parts, leading to type-III breaks that can coexist with type-II breaks, but situated further out. Type-III galaxies would be the result of an important radial redistribution of material throughout the entire disc, as well as a concentration of accreted material in the outskirts. In addition, type-III galaxies display the most efficient radial redistribution and the largest number of accreted stars, followed by type-I and II systems, suggesting that type-I galaxies may be an intermediate case between types-II and III. In general, the velocity dispersion profiles of all galaxies tend to flatten or even increase around the locations where the breaks are found. The age and metallicity profiles are also affected, exhibiting different inner gradients depending on their SB profile, being steeper in the case of type-II systems (as found observationally). The steep type-II profiles might be inherent to their formation rather than acquired via radial redistribution

Recovering star formation histories: Integrated-light analyses vs stellar colour-magnitude diagrams

Accurate star formation histories (SFHs) of galaxies are fundamental for understanding the build-up of their stellar content. However, the most accurate SFHs - those obtained from colour-magnitude diagrams (CMDs) of resolved stars reaching the oldest main sequence turnoffs (oMSTO) - are presently limited to a few systems in the Local Group. It is therefore crucial to determine the reliability and range of applicability of SFHs derived from integrated light spectroscopy, as this affects our understanding of unresolved galaxies from low to high redshift. To evaluate the reliability of current full spectral fitting techniques in deriving SFHs from integrated light spectroscopy by comparing SFHs from integrated spectra to those obtained from deep CMDs of resolved stars. We have obtained a high signal--to--noise (S/N $\sim$ 36.3 per \AA) integrated spectrum of a field in the bar of the Large Magellanic Cloud (LMC) using EFOSC2 at the 3.6 meter telescope at La Silla Observatory. For this same field, resolved stellar data reaching the oMSTO are available. We have compared the star formation rate (SFR) as a function of time and the age-metallicity relation (AMR) obtained from the integrated spectrum using {\tt STECKMAP}, and the CMD using the IAC-star/MinnIAC/IAC-pop set of routines. For the sake of completeness we also use and discuss other synthesis codes ({\tt STARLIGHT} and {\tt ULySS}) to derive the SFR and AMR from the integrated LMC spectrum. We find very good agreement (average differences $\sim$ 4.1 $\%$) between the SFR(t) and the AMR obtained using {\tt STECKMAP} on the integrated light spectrum, and the CMD analysis. {\tt STECKMAP} minimizes the impact of the age-metallicity degeneracy and has the advantage of preferring smooth solutions to recover complex SFHs by means of a penalized $\chi^2$. [abridged]Comment: 23 pages, 24 figures. Accepted for publication in A&A (6 Sep 2015

Integrated-light analyses vs. colour-magnitude diagrams - II. Leo A, an extremely young dwarf in the Local Group

Context. Most of our knowledge on the stellar component of galaxies is based on the analysis of distant systems and comes from integrated light data. It is important to test whether the results of the star formation histories (SFH) obtained with standard full-spectrum fitting methods are in agreement with those obtained through colour-magnitude diagram (CMD) fitting (usually considered the most reliable approach). Aims. We compare SFHs recovered from both techniques in Leo~A, a Local Group dwarf galaxy whose majority of stars formed during the last 8 Gyrs. This complements our previous findings in a field in the Large Magellanic Cloud bar, where star formation has been on-going since early epochs though at varying rates. Methods. We have used GTC/OSIRIS in long-slit mode to obtain a high-quality integrated light spectrum by scanning a selected region within Leo~A, for which a CMD reaching the old main mequence turn-off (oMSTO) is available from HST. We compared the SFH obtained from the two datasets, using state-of-art methods of integrated light ({\tt STECKMAP}) and resolved stellar population analysis. In the case of the CMD, we computed the SFH both from a deep CMD (observed with HST/ACS), and from a shallower one (archival data from HST/WFPC2). Results. The agreement between the SFHs recovered from the oMSTO CMD and from full spectrum fitting is remarkable, particularly regarding the time evolution of the star formation rate. The overall extremely low metallicity of Leo~A is recovered up to the last 2 Gyrs, when some discrepancies appear. A relatively high metallicity found for the youngest stars from the integrated data is a recurring feature that might indicate that the current models or synthesis codes should be revised, but that can be significantly mitigated using a more restrictive metallicity range... [Abridged]Comment: 15 pages, 12 figures, accepted for publication in A&

8.4GHz VLBI observations of SN2004et in NGC6946

We report on 8.4GHz Very Long Baseline Interferometry (VLBI) observations of the type II-P supernova SN2004et in the spiral galaxy NGC 6946, made on 20 February 2005 (151 days after explosion). The Very Large Array (VLA) flux density was 1.23$\pm$0.07 mJy, corresponding to an isotropic luminosity at 8.4GHz of (4.45$\pm$0.3)$\times10^{25}$ erg s$^{-1}$ Hz$^{-1}$ and a brightness temperature of (1.3$\pm$0.3)$\times10^{8}$ K. We also provide an improved source position, accurate to about 0.5 mas in each coordinate. The VLBI image shows a clear asymmetry. From model fitting of the size of the radio emission, we estimate a minimum expansion velocity of 15,700$\pm$2,000 km s$^{-1}$. This velocity is more than twice the expected mean expansion velocity estimated from a synchrotron self-absorbed emission model, thus suggesting that synchrotron self-absorption is not relevant for this supernova. With the benefit of an optical spectrum obtained 12 days after explosion, we favor an emission model which consists of two hot spots on an underlying expanding shell of width comparable to that of SN 1993J.Comment: Accepted for publication in A&A (22/05/07

Deterioro cognito disejecutivo en pacientes con enfermedad coronaria: asociación con variables clínicas

Las enfermedades cardiacas se asocian con un incremento del riesgo de deterioro cognitivo. Hemos estudiado en pacientes coronarios la presencia de deterioro cognitivo leve (DCL) disejecutivo y su asociación con variables sociodemográficas y clínicas. Se ha evaluado en 35 pacientes la función ejecutiva (Trail Making Test, TMT; puntuaciones ajustadas por edad y escolaridad, NEURONORMA). Los pacientes presentaron rendimiento normal o con DCL (percentil de distribución TMT<10%). Se compararon ambos grupos y se estudió la relación del TMT con variables sociodemográficas y clínicas (pruebas no paramétricas y estudio de regresión múltiple). Los pacientes (66 ± 9 años, 69,4% varones) se clasificaron en grupos con rendimiento normal (n=28, 80%) o con rendimiento ejecutivo deficitario (n=7, 20%). El grupo con DCL disejecutivo presentó mayor grado de angina (p=0.03, Canadian Cardiovascular Society), enfermedad de 3 vasos (p=0,04) e índice de masa corporal (p=0.03) y menor tensión arterial diastólica (p=0.02), hemoglobina (p=0.02) y hematocrito (p=0.0001); estas variables resultaron significativas del rendimiento en el TMT como variable dependiente (R2=0,62) Se muestra en pacientes con enfermedad coronaria una importante prevalencia de DCL disejecutivo asociado al nivel de angina y otros factores de riesgo cardiovascular. Se recomienda realizar evaluación neuropsicológica y seguimiento de pacientes con enfermedad coronaria severa por su mayor riesgo de deterioro cognitivo y funcionalUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Manejo del riego en grandes superficies de olivar en seto

El cultivo superintensivo revolucionó la olivicultura en los años 90 siendo un sistema apoyado en dos pilares básicos: alta densidad de plantación y casi total mecanización de las operaciones culturales. Desde entonces se ha extendido rápidamente por todo el Mundo. El riego es una herramienta fundamental para la rentabilidad de la mayor parte de estas plantaciones, sin embargo, existen cuestiones importantes que todavía no han sido resueltas de forma satisfactoria. Uno de los grandes retos es transferir el conocimiento disponible en cuanto a la gestión del riego empleando estrategias que mejoren la eficiencia en el uso del agua a explotaciones comerciales. En este estudio se evalúa los resultados obtenidos al aplicar en una parcela comercial una estrategia de riego deficitario controlado combinando medidas de estado hídrico en planta con técnicas de teledetección y mapeos de suelo para caracterizar el terreno sobre la productividad de la misma. El estudio se llevó a cabo durante 3 años (2015-2017) en un olivar comercial superintensivo variedad ‘Arbequina’ en plena producción localizado en Talavera la Real (Badajoz) en la Finca Explojoz. Se dispuso de una parcela Control regada según el criterio del técnico de la finca, comparada con otra parcela colindante en la que se estableció un riego deficitario controlado (parcela RDC) utilizando como referencia medidas de Potencial Hídrico del Tronco y señalando diferentes niveles de estrés en función del estado fenológico: brotación a endurecimiento de hueso de -1.2 MPa; de endurecimiento del hueso a envero de -2.0MPa; de envero a recolección -1.6 MPa. Dentro de cada parcela se identificaron 2 zonas de referencia una que se denominó "buena" y otra "mala" con características "a priori" diferentes. La selección de estas zonas se realizó empleando técnicas de teledetección y mapeo de suelos. Los resultados muestran que hubo diferencias de partida en las características de las dos parcelas de forma que en el primer año, con un mismo riego, la parcela Control tuvo más producción utilizando en ambas el mismo criterio de riego. Sin embargo, en los años sucesivos con una gestión diferenciada del riego, las producciones se igualaron e incluso se superaron en el caso de la parcela gestionada con un riego deficitario controlado adaptado a las características concretas de la parcela y consiguiendo equilibrar la productividad de la finca.Comunicación presentada al XXXVII Congreso Nacional de Riegos, celebrado en Don Benito del 4 al 6 de Junio de 2019 y organizada por la Asociación Española de Riegos y Drenajes y la Universidad de Extremadur

Mass-metallicity relation explored with CALIFA I. Is there a dependence on the star-formation rate?

We studied the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2−3 effective radii), with a resolution high enough to separate individual Hii regions and/or aggregations. About 3000 individual Hii regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise ratio to derive the oxygen abundance and star-formation rate associated with each region. In addition, we computed the integrated and spatially resolved stellar masses (and surface densities) based on SDSS photometric data. We explore the relations between the stellar mass, oxygen abundance and star-formation rate using this dataset. We derive a tight relation between the integrated stellar mass and the gas-phase abundance, with a dispersion lower than the one already reported in the literature (σΔlog (O/H) = 0.07 dex). Indeed, this dispersion is only slightly higher than the typical error derived for our oxygen abundances. However, we found no secondary relation with the star-formation rate other than the one induced by the primary relation of this quantity with the stellar mass. The analysis for our sample of ∼3000 individual Hii regions confirms (i) a local mass-metallicity relation and (ii) the lack of a secondary relation with the star-formation rate. The same analysis was performed with similar results for the specific star-formation rate. Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, such like that of gas accretion by inflow and/or metal loss due to outflows. In essence, late-type/disk-dominated galaxies seem to be in a quasi-steady situation, with a behavior similar to the one expected from an instantaneous recycling/closed-box model.Nacional de Investigación y Desarrollo funding programs of the Spanish Ministerio de Ciencia e Innovación AYA2010-22111-C03-03 AYA2010-10904ERamon y Cajal project of the spanish Ministerio de Economía y Competitividad RyC-2011-07590Academy of Sciences of the Czech Republic (ASCR Internal support program of international cooperation projects-PIPPMS) M100031241 M100031201Czech Republic program for the long-term development of the research institution RVO67985815Plan Nacional de Investigación y Desarrollo funding program AYA2010-15081Consejo Nacional de Ciencia y Tecnología (CONACyT)Spanish grant AYA2010-15169Junta de Andalucía TIC114Excellence Project P08-TIC-03531Consejo Superior de Investigaciones Científicas (CSIC)Junta para la Ampliación de EstudiosEuropean Social Fund (ESF)spanish programme of International Campus of Excellence MoncloaSpanish PNAYA AYA2010-21887Spanish Government CSD2006-00070 AYA2012-38491-C02-02Junta de Andalucía TIC114Autonomic Government of Andalusia P08-TIC-4075 TIC-126CienciaPortuguese Foundation for Science and TechnologyEuropean Commission European Commission Joint Research Centre European Social Fund (ESF)Portuguese Foundation for Science and Technology SFRH/BPD/66958/2009National Science Foundation (NSF

Observational hints of radial migration in disc galaxies from CALIFA

Context. According to numerical simulations, stars are not always kept at their birth galactocentric distances but they have a tendency to migrate. The importance of this radial migration in shaping galactic light distributions is still unclear. However, if radial migration is indeed important, galaxies with different surface brightness (SB) profiles must display differences in their stellar population properties. Aims: We investigate the role of radial migration in the light distribution and radial stellar content by comparing the inner colour, age, and metallicity gradients for galaxies with different SB profiles. We define these inner parts, avoiding the bulge and bar regions and up to around three disc scale lengths (type I, pure exponential) or the break radius (type II, downbending; type III, upbending). Methods: We analysed 214 spiral galaxies from the CALIFA survey covering different SB profiles. We made use of GASP2D and SDSS data to characterise the light distribution and obtain colour profiles of these spiral galaxies. The stellar age and metallicity profiles were computed using a methodology based on full-spectrum fitting techniques (pPXF, GANDALF, and STECKMAP) to the Integral Field Spectroscopic CALIFA data. Results: The distributions of the colour, stellar age, and stellar metallicity gradients in the inner parts for galaxies displaying different SB profiles are unalike as suggested by Kolmogorov-Smirnov and Anderson-Darling tests. We find a trend in which type II galaxies show the steepest profiles of all, type III show the shallowest, and type I display an intermediate behaviour. Conclusions: These results are consistent with a scenario in which radial migration is more efficient for type III galaxies than for type I systems, where type II galaxies present the lowest radial migration efficiency. In such a scenario, radial migration mixes the stellar content, thereby flattening the radial stellar properties and shaping different SB profiles. However, in light of these results we cannot further quantify the importance of radial migration in shaping spiral galaxies, and other processes, such as recent star formation or satellite accretion, might play a role

Drake-Scotia Sea gateways: onset and evolution of the Drake Passage and Scotia Sea, implications for global ocean circulation and climate

Australasian IODP Regional Planing Workshop (2017. Sidney)Instituto Geológico y Minero de España, EspañaInstituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Científicas, EspañaIstituto Nazionale di Oceanografia e Geofisica Sperimentale, ItaliaSan Diego State University, Estados UnidosPeer reviewe

Dielectrophoretic assembly of liquid-phase-exfoliated TiS3 nanoribbons for photodetecting applications

Liquid-phase exfoliation is a technique capable of producing large quantities of two-dimensional materials in suspension. Despite many efforts in the optimization of the exfoliation process itself, not much has been done towards the integration of liquid-phase-exfoliated materials in working solid-state devices. In this article, we use dielectrophoresis to direct the assembly of liquid-phase-exfoliated TiS3 nanoribbons between two gold electrodes to produce photodetectors working in the visible region. Through electrical and optical measurements we characterize the responsivity of the device and we find values as large as 3.8 mA W-1, which are more than one order of magnitude higher compared to state-of-the-art devices based on liquid-phase-exfoliated two-dimensional materials assembled by drop-casting or ink-jet methods