Directly from HH-flux to the family of three nonlocal RR-flux theories

In this article we consider T-dualization of the 3D closed bosonic string in the weakly curved background - constant metric and Kalb-Ramond field with one non-zero component, $B_{xy}=Hz$, where field strength $H$ is infinitesimal. We use standard and generalized Buscher T-dualization procedure and make T-dualization starting from coordinate $z$, via $y$ and finally along $x$ coordinate. All three theories are {\it nonlocal}, because variable $\Delta V$, defined as line integral, appears as an argument of background fields. After the first T-dualization we obtain commutative and associative theory, while after we T-dualize along $y$, we get, $\kappa$-Minkowski-like, noncommutative and associative theory. At the end of this T-dualization chain we come to the theory which is both noncommutative and nonassociative. The form of the final T-dual action does not depend on the order of T-dualization while noncommutativity and nonassociativity relations could be obtained from those in the $x\to y\to z$ case by replacing $H\to - H$.Comment: Section 4 (quantum aspect of the problem) is added, some other explanations, clarifications and comments adde

Die Auswirkungen aus Evaluierung und Aktivierung auf die Speicherung affektiver Stimuli

Na uzorku od 45 ispitanika ispitani su efekti evaluacije i aktivacije na neposredno i odgođeno slobodno dosjećanje, prepoznavanje i inicijalnu fazu obrade afektivnih podražaja. Dobiveni rezultati pokazuju da se i pri neposrednom i pri odgođenom dosjećanju ispitanici više dosjećaju afektivnih podražaja niske aktivacije, dok se podražaji visoke aktivacije bolje prepoznaju i izazivaju više netočnih "DA" odgovora. Samo pri neposrednom dosjećanju neugodni afektivni podražaji dosjećaju se bolje od ugodnih, dok pri odgođenom dosjećanju nema razlike između ugodnih i neugodnih afektivnih podražaja. Također, neugodni afektivni podražaji bolje se prepoznaju, dok ugodni podražaji izazivaju više netočnih "DA" odgovora. Općenito, rezultati ovoga istraživanja pokazuju da evaluacija i aktivacija, samostalno i u interakciji, imaju značajan utjecaj na pamćenje afektivnih podražaja. Utjecaj tih dviju dimenzija na pamćenje afektivnih podražaja je različit, a također je ovisan i o korištenom tipu testa pamćenja. Navedeni su rezultati interpretirani u kontekstu postojećih teorija o ulozi evaluacije i aktivacije pri pamćenju afektivnih podražaja.On a sample of 45 examinees the authors have examined the effects of evaluation and activation on immediate and delayed free memory, recognition and the initial phase of processing affective stimuli. The results obtained indicate that both in immediate and delayed memory examinees remember low activation affective stimuli more, while high activation stimuli are better recognized and produce more incorrect (yes) answers. Only in immediate memory are the unpleasant affective stimuli remembered better than the pleasant ones, while in delayed memory there is no difference between pleasant and unpleasant affective stimuli. Also, the unpleasant affective stimuli are better recognized, while the pleasant ones give rise to more incorrect (yes) answers. In general, the results of this research show that evaluation and activation both independently and in interaction have a significant influence on the memory of affective stimuli. The influence of these two dimensions on remembering affective stimuli is diverse, and is also dependent on the type of memory test used. The aforementioned results have been interpreted in the context of existing theories on the role of evaluation and activation in remembering affective stimuli.In einer Gruppe von 45 Testpersonen wurden die Auswirkungen von Evaluierung und Aktivierung auf die unmittelbare sowie die zeitlich verzögerte, freie Abberufung, Wiedererkennung und initiale Verarbeitung von im Gedächtnis gespeicherten affektiven Stimuli untersucht. Die Resultate zeigen, dass sowohl bei der unmittelbaren als auch der zeitlich verzögerten Abberufung gespeicherter Stimuli die Testpersonen sich überwiegend affektiver Stimuli von niedrigem Aktivierungsgrad entsannen, während Stimuli hohen Aktivierungsgrads besser erkannt werden und mehr unkorrekte Ja-Antworten zur Folge haben. Nur im Falle des unmittelbaren Entsinnens werden unangenehme affektive Stimuli besser aus dem Gedächtnis abberufen als angenehme, während es im Falle zeitlich verzögerten Entsinnens keinen Unterschied zwischen angenehmen und unangenehmen affektiven Stimuli gibt. Ebenso gilt, dass unangenehme affektive Stimuli besser erkannt werden, während angenehme Stimuli mehr unkorrekte Ja-Antworten hervorrufen. Die Ergebnisse dieser Untersuchung zeigen ganz allgemein, dass Evaluierung und Aktivierung ”jeweils, aber auch in Interaktion” einen wesentlichen Einfluss auf die Abberufung affektiver Stimuli aus dem Gedächtnis haben. Der Einfluss dieser beiden Dimensionen auf die Speicherung affektiver Stimuli ist jeweils unterschiedlich und außerdem abhängig vom Typus des eingesetzten Memo-Tests. Die Interpretation der angeführten Ergebnisse bewegt sich im Kontext der bestehenden Theorien zur Rolle der Evaluierung und Aktivierung bei der Abberufung affektiver Stimuli aus dem Gedächtnis

The Rest-frame Optical Colors of 99,000 SDSS Galaxies

We synthesize the rest-frame Stroemgren colors using SDSS spectra for 99,088 galaxies selected from Data Release 1. This narrow-band ~200 AA photometric system (uz, vz, bz, yz), first designed for the determination of effective temperature, metallicity and gravity of stars, measures the continuum spectral slope of galaxies in the rest-frame 3200-5800 AA wavelength range. Galaxies form a remarkably narrow locus (~0.03 mag) in the resulting color-color diagram. The Bruzual & Charlot population synthesis models suggest that the position of a galaxy along this locus is controlled by a degenerate combination of metallicity and age of the dominant stellar population. Galaxy distribution along the locus is bimodal, with the local minimum corresponding to an ~1 Gyr old single stellar population. The position perpendicular to the locus is independent of metallicity and age, and reflects the galaxy's dust content, as implied by both the models and the statistics of IRAS detections. A comparison of this locus with the galaxy locus in the H_delta-D_n(4000) diagram, utilized by Kauffmann et al. (2003) to estimate stellar masses, reveals a tight correlation, although the two analyzed spectral ranges barely overlap. Overall, the galaxy spectral energy distribution in the entire UV to near-IR range can be described as a single-parameter family with an accuracy of 0.1 mag, or better. This nearly one-dimensional distribution of galaxies in the multi-dimensional space of measured parameters strongly supports the conclusion of Yip et al. (2004), based on a principal component analysis, that SDSS galaxy spectra can be described by a small number of eigenspectra. Apparently, the contributions of stellar populations that dominate the optical emission from galaxies are combined in a simple and well-defined way.Comment: Accepted for publication in MNRAS; 19 pages, 28 color figure

Source Matching in the SDSS and RASS: Which Galaxies are Really X-ray Sources?

The current view of galaxy formation holds that all massive galaxies harbor a massive black hole at their center, but that these black holes are not always in an actively accreting phase. X-ray emission is often used to identify accreting sources, but for galaxies that are not harboring quasars (low-luminosity active galaxies), the X-ray flux may be weak, or obscured by dust. To aid in the understanding of weakly accreting black holes in the local universe, a large sample of galaxies with X-ray detections is needed. We cross-match the ROSAT All Sky Survey (RASS) with galaxies from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) to create such a sample. Because of the high SDSS source density and large RASS positional errors, the cross-matched catalog is highly contaminated by random associations. We investigate the overlap of these surveys and provide a statistical test of the validity of RASS-SDSS galaxy cross-matches. SDSS quasars provide a test of our cross-match validation scheme, as they have a very high fraction of true RASS matches. We find that the number of true matches between the SDSS main galaxy sample and the RASS is highly dependent on the optical spectral classification of the galaxy; essentially no star-forming galaxies are detected, while more than 0.6% of narrow-line Seyferts are detected in the RASS. Also, galaxies with ambiguous optical classification have a surprisingly high RASS detection fraction. This allows us to further constrain the SEDs of low-luminosity active galaxies. Our technique is quite general, and can be applied to any cross-matching between surveys with well-understood positional errors.Comment: 10 pages, 10 figures, submitted to The Astronomical Journal on 19 June 200

The UV, Optical, and IR Properties of SDSS Sources Detected by GALEX

We discuss the UV, optical, and IR properties of the SDSS sources detected by GALEX as part of its All-sky Imaging Survey Early Release Observations. Virtually all of the GALEX sources in the overlap region are detected by SDSS. GALEX sources represent ~2.5% of all SDSS sources within these fields and about half are optically unresolved. Most unresolved GALEX/SDSS sources are bright blue turn-off thick disk stars and are typically detected only in the GALEX near-UV band. The remaining unresolved sources include low-redshift quasars, white dwarfs, and white dwarf/M dwarf pairs, and these dominate the optically unresolved sources detected in both GALEX bands. Almost all the resolved SDSS sources detected by GALEX are fainter than the SDSS 'main' spectroscopic limit. These sources have colors consistent with those of blue (spiral) galaxies (u-r<2.2), and most are detected in both GALEX bands. Measurements of their UV colors allow much more accurate and robust estimates of star-formation history than are possible using only SDSS data. Indeed, galaxies with the most recent (<20 Myr) star formation can be robustly selected from the GALEX data by requiring that they be brighter in the far-UV than in the near-UV band. However, older starburst galaxies have UV colors similar to AGN, and thus cannot be selected unambiguously on the basis of GALEX fluxes alone. With the aid of 2MASS data, we construct and discuss median 10 band UV-optical-IR spectral energy distributions for turn-off stars, hot white dwarfs, low-redshift quasars, and spiral and elliptical galaxies. We point out the high degree of correlation between the UV color and the contribution of the UV flux to the UV-optical-IR flux of galaxies detected by GALEX.Comment: 35 pages, 11 figures, 3 tables; to appear in the AJ. PS with better figures available from http://www.astro.washington.edu/agueros/pub

A Huge Filamentary Structure at z=0.55 and Star Formation Histories of Galaxies at z<1

We report a definitive confirmation of a large-scale structure around the super rich cluster CL0016+1609 at z=0.55. We made spectroscopic follow-up observations with FOCAS on Subaru along the large filamentary structure identified in our previous photometric studies. We have confirmed the physical connection of the huge filament extending over 20 Mpc in the N-S direction, and another filament extending from the main cluster to the East. Based on a simple energy argument, we show that it is likely that most of the clumps are bound to the main CL0016 cluster. This structure is surely one of the most prominent confirmed structures ever identified in the distant Universe, which then serves as an ideal laboratory to examine the environmental variation of galaxy properties. We draw star formation histories of galaxies from the composite spectra of red galaxies in field, group, and cluster environments. Combining the results from our previous studies, we find that red galaxies in groups at z~0.8 and red field galaxies at z~0.5 show strong Hd absorption lines for their D4000 indices. These are the environments in which we observed the on-going build-up of the colour-magnitude relation in our previous photometric analyses. The strong Hd absorption lines imply that their star formation is truncated on a relatively short time scale. We suggest that a galaxy-galaxy interaction is the most likely physical driver of the truncation of star formation and thus responsible for the build-up of the colour-magnitude relation since z~1. (Abridged)Comment: 13 pages, 5 figures, accepted for publication in MNRA

The Ultraviolet, Optical, and Infrared Properties of Sloan Digital Sky Survey Sources Detected by GALEX

We discuss the ultraviolet, optical, and infrared properties of the Sloan Digital Sky Survey (SDSS) sources detected by the Galaxy Evolution Explorer (GALEX) as part of its All-sky Imaging Survey Early Release Observations. Virtually all (>99%) the GALEX sources in the overlap region are detected by SDSS; those without an SDSS counterpart within our 6'' search radius are mostly unflagged GALEX artifacts. GALEX sources represent ~2.5% of all SDSS sources within these fields, and about half are optically unresolved. Most unresolved GALEX-SDSS sources are bright (r < 18 mag), blue, turnoff, thick-disk stars and are typically detected only in the GALEX near-ultraviolet (NUV) band. The remaining unresolved sources include low-redshift quasars (z < 2.2), white dwarfs, and white dwarf–M dwarf pairs, and these dominate the optically unresolved sources detected in both GALEX bands. Almost all the resolved SDSS sources detected by GALEX are fainter than the SDSS main spectroscopic limit. (Conversely, of the SDSS galaxies in the main spectroscopic sample, about 40% are detected in at least one GALEX band.) These sources have colors consistent with those of blue (spiral) galaxies (u - r < 2.2), and most are detected in both GALEX bands. Measurements of their UV colors allow much more accurate and robust estimates of star formation history than are possible using only SDSS data. Indeed, galaxies with the most recent (lesssim20 Myr) star formation can be robustly selected from the GALEX data by requiring that they be brighter in the far-ultraviolet (FUV) than in the NUV band. However, older starburst galaxies have UV colors similar to those of active galactic nuclei and thus cannot be selected unambiguously on the basis of GALEX fluxes alone. Additional information, such as spatially resolved FUV emission, optical morphology, or X-ray and radio data, is needed before blue GALEX colors can be unambiguously interpreted as a sign of recent star formation. With the aid of Two Micron All Sky Survey data, we construct and discuss median 10-band UV through infrared spectral energy distributions for turnoff stars, hot white dwarfs, low-redshift quasars, and spiral and elliptical galaxies. We point out the high degree of correlation between the UV color and the contribution of the UV flux to the UV through infrared flux of galaxies detected by GALEX; for example, this correlation can be used to predict the SDSS z-band measurement, using only two GALEX fluxes, with a scatter of only 0.7 mag

The census of nuclear activity of late-type galaxies in the Virgo cluster

The first spectroscopic census of AGNs associated to late-type galaxies in the Virgo cluster is carried on by observing 213 out of a complete set of 237 galaxies more massive than M_dyn>10^{8.5} solar masses. Among them, 77 are classified as AGNs (including 21 transition objects, 47 LINERs and 9 Seyferts), and comprize 32% of the late-type galaxies in Virgo. Due to spectroscopic incompleteness at most 21 AGNs are missed in the survey, so that the fraction would increase up to 41%. Using corollary Near-IR observations, that enable us to estimate galaxies dynamical masses, it is found that AGNs are hosted exclusively in massive galaxies, i.e. M_dyn\gsim 10^{10} solar masses. Their frequency increases steeply with the dynamical mass from zero at M_dyn\approx10^{9.5} solar masses to virtually 1 at M_dyn>10^{11.5} solar masses. These frequencies are consistent with the ones of low luminosity AGNs found in the general field by the SDSS. Massive galaxies that harbor AGNs commonly show conspicuous r-band star-like nuclear enhancements. Conversely they often, but not necessarily contain massive bulges. Few well known AGNs (e.g. M61, M100, NGC4535) are found in massive Sc galaxies with little or no bulge. The AGN fraction seems to be only marginally sensitive to galaxy environment. We infer the black hole masses using the known scaling relations of quiescent black holes. No black holes lighter than $\sim 10^6$ \msol are found active in our sample.Comment: The paper contains 13 figures and 5 tables; accepted for publication in MNRA

A new method to separate star forming from AGN galaxies at intermediate redshift: The submillijansky radio population in the VLA-COSMOS survey

We explore the properties of the submillijansky radio population at 20 cm by applying a newly developed optical color-based method to separate star forming (SF) from AGN galaxies at intermediate redshifts (z<1.3). Although optical rest-frame colors are used, our separation method is shown to be efficient, and not biased against dusty starburst galaxies. This classification method has been calibrated and tested on a local radio selected optical sample. Given accurate multi-band photometry and redshifts, it carries the potential to be generally applicable to any galaxy sample where SF and AGN galaxies are the two dominant populations. In order to quantify the properties of the submillijansky radio population, we have analyzed ~2,400 radio sources, detected at 20 cm in the VLA-COSMOS survey. 90% of these have submillijansky flux densities. We classify the objects into 1) star candidates, 2) quasi stellar objects, 3) AGN, 4) SF, and 5) high redshift (z>1.3) galaxies. We find, for the composition of the submillijansky radio population, that SF galaxies are not the dominant population at submillijansky flux levels, as previously often assumed, but that they make up an approximately constant fraction of 30-40% in the flux density range of ~50 microJy to 0.7 mJy. In summary, based on the entire VLA-COSMOS radio population at 20 cm, we find that the radio population at these flux densities is a mixture of roughly 30-40% of SF and 50-60% of AGN galaxies, with a minor contribution (~10%) of QSOs.Comment: 26 pages, 26 figures; accepted for publication in ApJ