GUNDAM : A toolkit for fast spatial correlation functions in galaxy surveys

We describe the capabilities of a new software package to calculate two-point correlation functions (2PCFs) of large galaxy samples. The code can efficiently estimate 3D/projected/angular 2PCFs with a variety of statistical estimators and bootstrap errors, and is intended to provide a complete framework (including calculation, storage, manipulation, and plotting) to perform this type of spatial analysis with large redshift surveys. GUNDAM implements a very fast skip list/linked list algorithm that efficiently counts galaxy pairs and avoids the computation of unnecessary distances. It is several orders of magnitude faster than a naive pair counter, and matches or even surpass other advanced algorithms. The implementation is also embarrassingly parallel, making full use of multicore processors or large computational clusters when available. The software is designed to be flexible, user friendly and easily extensible, integrating optimized, well-tested packages already available in the astronomy community. Out of the box, it already provides advanced features such as custom weighting schemes, fibre collision corrections and 2D correlations. GUNDAM will ultimately provide an efficient toolkit to analyse the large-scale structure 'buried' in upcoming extremely large data sets generated by future surveys.Fil: Donoso, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; Argentin

Del porvenir del castellano en Filipinas

En la actualidad estamos presenciando la aparición de multitud de fenómenos culturales de una riqueza sorprendente, los cuales nos permiten analizar con nuevas herramientas los procesos antropológicos. En tal sentido, la cultura nos aparece como un elemento más que las comunidades humanas usan para adaptarse al medio en el que viven, y las propuestas de nacionalización cultural tienden a ser confrontadas con la crítica post-colonial. Por otro lado, en un mundo en el que la globalización parece una amenaza cultural, se reformulan las corrientes nacionalistas en términos de etnicidad, lo que puede llevar a entender la cultura más como un arma que como un patrimonio. Así pues, se nos presentan dos vertientes que pueden afectar al individuo común en su percepción de la realidad, y pueden escindirle mediante conflictos de adaptación cultural, entre lo uno y lo diverso. El caso de Filipinas es paradigmático a tal respecto, pues ha tenido que enfrentarse a multitud de escenarios culturales ajenos a su matriz, y ha tenido que lidiar con ellos para confeccionar su percepción del mundo

Evolution of Radio Galaxies Across Cosmic Time

Despite being a minority among the total population of galaxies, radio galaxies have gained increasing attention, because of the energetic feedback they can provide to the surrounding environment. These systems host an active nucleus that produces large amounts of energy in the form of radio/X-ray emitting jets, injecting energy that in some cases can balance the radiative loses of the gas that cools and condenses within massive halos of dark matter. Therefore, if we want to understand galaxy formation and evolution, we have to understand the role of active galactic nuclei (AGN) in the galaxy assembly process. My work concentrated, first, on constructing a complete sample of radio galaxies. This is not an easy task as they have very different morphologies in different surveys, and ofter break up into separate components. These components must be correctly associated with a unique optical galaxy. We cross-correlated two different radio surveys (NVSS and FIRST) with a sample of luminous red galaxies derived from the Sloan Digital Sky Survey (SDSS). The NVSS provides accurate flux measurements for extended sources, while the angular resolution of FIRST allows the host galaxy to be identified accurately. We also improved the matching of sources below the nominal 1 mJy detection limit of FIRST, to increase the reliability and completeness of the final catalogue. These techniques allowed us to assemble the largest radio galaxy catalogue to date, consisting of around 14,000 radio–loud AGN at intermediate redshifts (0.4 < z < 0.8), with 1.4 GHz fluxes above 3.5 mJy. The matching criteria were tested and refined using Monte–Carlo simulations, leading to an estimated reliability of ∼98.3% and completeness level of about 95% for our catalogue. With this catalog in hand, we were able to compare radio galaxies at z∼0.55 with similar samples in the local universe. We studied the evolutionary properties of radio galaxies, how their spatial density changes as function of time and how the fraction of radio emitting sources varies with galaxies properties such as stellar mass, radio luminosity and redshift. We present a new determination of the luminosity function of radio AGN at z∼0.55 and compare this to the luminosity function of nearby (z∼0.1) radio sources from the SDSS main survey. The comoving number density of radio AGN with luminosities less than 10^25 W/Hz increases by a factor ∼1.5 between z=0.1 and z=0.55. At higher luminosities, this factor increases sharply, reaching values of more than 10 at radio luminosities larger than 10^26 W/Hz. We then study how the relation between radio AGN and their host galaxies evolves with redshift. Our main conclusion is that the fraction of radio–loud AGN increases towards higher redshift in all massive galaxies, but the evolution is particularly strong for the lower mass galaxies in our sample. These trends may be understood if there are two classes of radio galaxies (likely associated with the “radio” and “quasar mode” dichotomy) that have different fuelling/triggering mechanisms and hence evolve in different ways. We conclude that stellar mass seems to be the a very important factor in deciding whether a galaxy develops bright, powerful radio jets. There is also the suggestion that the environment of a galaxy is also crucial in deciding whether it becomes radio-loud. To address this question, we studied how radio galaxies are clustered in the universe and quantified the clustering dependence on stellar mass and radio power. We do this by computing the cross-correlation function between radio galaxies and the parent LRG population. In order to isolate the true clustering of RLAGN, we compare respect to control radio-quiet galaxies selected with the same properties as radio AGN. The main result is that RLAGN are significantly more clustered than radio-quiet objects, particularly below ∼1 Mpc/h, indicating that the gaseous environment of a radio sources at the scale of its dark matter halo is important in modulating the observed output power and determining its radio loudness. Unification models predict that the environments of radio-loud galaxies and radio-loud quasars should be equivalent, as they represent the same object that is observed at different orientations with respect to the line of sight. We have compared our clustering measurements for these two types of objects, setting important restrictions on the conditions that must be met if the models are valid. We find evidence that the idea of unification can hold only for the most luminous radio galaxies in our sample, with radio power above ∼10^26 W/Hz. Finally, we have also modeled the radio-loud population of AGN at z=0.5 by applying a simple prescription for the distribution of radio galaxies in dark matter haloes extracted from N-body simulations. This proves the applicability at high redshift of models that have been shown to work well in the local universe and test directly the radio-mode heating recipe implemented in semianalyitcal models of galaxy formation. By combining an estimate for the mechanical power of radio sources with our determination of the luminosity function we have been able to estimate the heating effect that RLAGN produce in haloes of different mass. The heating power in haloes of ∼10^15 M_sun/h, the most massive in our sample, is a factor of 6-7 larger than in less massive systems of ∼10^13 M_sun/h, and a factor of ∼2.5 larger at z=0.5 than at in the local universe. This result can be used to improve the implementation of radio feedback in models of galaxy formation

Occurrence of LINER galaxies within the galaxy group environment

We study the properties of a sample of 3967 low-ionization nuclear emission-line region (LINER) galaxies selected from SDSS-DR7, with respect to their proximity to galaxy groups. The host galaxies of LINERs have been analysed and compared with a well-defined control sample of 3841 non-LINER galaxies matched in redshift, luminosity, colour, morphology, age and stellar mass content. We find no difference between LINER and control galaxies in terms of the colour and age of stellar population as a function of the virial mass and distance to the geometric centre of the group. However, we find that LINERs are more likely to populate low-density environments in spite of their morphology, which is typical of high-density regions such as rich galaxy clusters. For rich (poor) galaxy groups, the occurrence of LINERs is approximately two times lower (higher) than the occurrence of matched, non-LINER galaxies. Moreover, LINER hosts do not seem to follow the expected morphology–density relation in groups of high virial mass. The high frequency of LINERs in low-density regions could be due to the combination of a sufficient gas reservoir to power the low-ionization emission and/or enhanced galaxy interaction rates benefiting the gas flow towards their central regions.Fil: Coldwell Lloveras, Georgina Vanesa. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pereyra, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Alonso Giraldes, Maria Sol. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Donoso, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Duplancic Videla, Maria Fernanda. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

El Juego de poker : una mirada desde la psicología social

La presente investigación busca desde la psicología social, el ocio y el juego indagar el papel que cumplen los diversos factores implicados en el juego recreativo de póker tales como las relaciones sociales, los roles y las reglas al interior del grupo y los referentes comunicacionales . El estudio es de orden cualitativo, en el cual participaron tres personas de sexo masculino, jugadores recurrentes del Club de Afazar Póker ubicado en el centro de la ciudad de Bogotá

Alignment between Luminous Red Galaxies and surrounding structures at z∼ 0.5z\sim ~0.5

We analyse a high redshift sample ($0.4<z<0.5$) of LRG's extracted from the Sloan Digital Sky Survey Data Release 4 and their surrounding structures to explore the presence of alignment effects of these bright galaxies with neighbor objects. In order to avoid projection effects we compute photometric redshifts for galaxies within 3~\mpc in projection of LRGs and calculate the relative angle between the LRG major axis and the direction to neighbors within 1000 km/s. We find a clear signal of alignment between LRG orientations and the distribution of galaxies within 1.5\mpc. The alignment effects are present only for the red population of tracers, LRG orientation is uncorrelated to the blue population of neighbor galaxies. These results add evidence to the alignment effects between primaries and satellites detected at low redshifts. We conclude that such alignments were already present at $z\sim 0.5$Comment: The paper contain 6 pages, 5 figures and 1 table Acepted MNRAS 2006 March 1

Spitzer Photometry of WISE-Selected Brown Dwarf and Hyper-Luminous Infrared Galaxy Candidates

We present Spitzer 3.6 and 4.5 $\mu$m photometry and positions for a sample of 1510 brown dwarf candidates identified by the WISE all-sky survey. Of these, 166 have been spectroscopically classified as objects with spectral types M(1), L(7), T(146), and Y(12); Sixteen other objects are non-(sub)stellar in nature. The remainder are most likely distant L and T dwarfs lacking spectroscopic verification, other Y dwarf candidates still awaiting follow-up, and assorted other objects whose Spitzer photometry reveals them to be background sources. We present a catalog of Spitzer photometry for all astrophysical sources identified in these fields and use this catalog to identify 7 fainter (4.5 $\mu$m $\sim$ 17.0 mag) brown dwarf candidates, which are possibly wide-field companions to the original WISE sources. To test this hypothesis, we use a sample of 919 Spitzer observations around WISE-selected high-redshift hyper-luminous infrared galaxy (HyLIRG) candidates. For this control sample we find another 6 brown dwarf candidates, suggesting that the 7 companion candidates are not physically associated. In fact, only one of these 7 Spitzer brown dwarf candidates has a photometric distance estimate consistent with being a companion to the WISE brown dwarf candidate. Other than this there is no evidence for any widely separated ($>$ 20 AU) ultra-cool binaries. As an adjunct to this paper, we make available a source catalog of $\sim$ 7.33 $\times 10^5$ objects detected in all of these Spitzer follow-up fields for use by the astronomical community. The complete catalog includes the Spitzer 3.6 and 4.5 $\mu$m photometry, along with positionally matched $B$ and $R$ photometry from USNO-B; $J$, $H$, and $K_s$ photometry from 2MASS; and $W1$, $W2$, $W3$, and $W4$ photometry from the WISE all-sky catalog

Spitzer Photometry of WISE-Selected Brown Dwarf and Hyper-Lumninous Infrared Galaxy Candidates

We present Spitzer 3.6 and 4.5 micrometer photometry and positions for a sample of 1510 brown dwarf candidates identified by the Wide-field Infrared Survey Explorer (WISE) all-sky survey. Of these, 166 have been spectroscopically classified as objects with spectral types M(1), L(7), T(146), and Y(12). Sixteen other objects are non-(sub)stellar in nature. The remainder are most likely distant L and T dwarfs lacking spectroscopic verification, other Y dwarf candidates still awaiting follow-up, and assorted other objects whose Spitzer photometry reveals them to be background sources. We present a catalog of Spitzer photometry for all astrophysical sources identified in these fields and use this catalog to identify seven fainter (4.5 m to approximately 17.0 mag) brown dwarf candidates, which are possibly wide-field companions to the original WISE sources. To test this hypothesis, we use a sample of 919 Spitzer observations around WISE-selected high-redshift hyper-luminous infrared galaxy candidates. For this control sample, we find another six brown dwarf candidates, suggesting that the seven companion candidates are not physically associated. In fact, only one of these seven Spitzer brown dwarf candidates has a photometric distance estimate consistent with being a companion to the WISE brown dwarf candidate. Other than this, there is no evidence for any widely separated (greater than 20 AU) ultra-cool binaries. As an adjunct to this paper, we make available a source catalog of 7.33 x 10(exp 5) objects detected in all of these Spitzer follow-up fields for use by the astronomical community. The complete catalog includes the Spitzer 3.6 and 4.5 m photometry, along with positionally matched B and R photometry from USNO-B; J, H, and Ks photometry from Two Micron All-Sky Survey; and W1, W2, W3, and W4 photometry from the WISE all-sky catalog

Associations Between the Modified Food Standard Agency Nutrient Profiling System Dietary Index and Cardiovascular Risk Factors in an Elderly Population

Background: Helping consumers to improve the nutritional quality of their diet is a key public health action to prevent cardiovascular diseases (CVDs). The modified version of the Food Standard Agency Nutrient Profiling System Dietary Index (FSAm-NPS DI) underpinning the Nutri-Score front-of-pack label has been used in public health strategies to address the deleterious consequences of poor diets. This study aimed to assess the association between the FSAm-NPS DI and some CVD risk factors including body mass index (BMI), waist circumference, plasma glucose levels, triglyceride levels, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and diastolic and systolic blood pressure. Materials and Methods: Dietary intake was assessed at baseline and after 1 year of follow-up using a 143-item validated semi-quantitative food-frequency questionnaire. Dietary indices based on FSAm-NPS applied at an individual level were computed to characterize the diet quality of 5,921 participants aged 55-75 years with overweight/obesity and metabolic syndrome from the PREDIMED-plus cohort. Associations between the FSAm-NPS DI and CVD risk factors were assessed using linear regression models. Results: Compared to participants with a higher nutritional quality of diet (measured by a lower FSAm-NPS DI at baseline or a decrease in FSAm-NPS DI after 1 year), those participants with a lower nutritional quality of diet (higher FSAm-NPS DI or an increase in score) showed a significant increase in the levels of plasma glucose, triglycerides, diastolic blood pressure, BMI, and waist circumference (beta coefficient [95% confidence interval]; P for trend) (1.67 [0.43, 2.90]; <0.001; 6.27 [2.46, 10.09]; <0.001; 0.56 [0.08, 1.05]; 0.001; 0.51 [0.41, 0.60]; <0.001; 1.19 [0.89, 1.50]; <0.001, respectively). No significant associations in relation to changes in HDL and LDL-cholesterol nor with systolic blood pressure were shown. Conclusion: This prospective cohort study suggests that the consumption of food items with a higher FSAm-NPS DI is associated with increased levels of several major risk factors for CVD including adiposity, fasting plasma glucose, triglycerides, and diastolic blood pressure. However, results must be cautiously interpreted because no significant prospective associations were identified for critical CVD risk factors, such as HDL and LDL-cholesterol, and systolic blood pressure