UV observations of the globular cluster M10 from HST and GALEX. The BSS population

We present a combination of high-resolution Hubble Space Telescope and wide-field ground-based and Galaxy Evolution Explorer data of the Galactic Globular Cluster M10 (NGC6254). By using this large data-set we determined the center of gravity of the cluster and we built its density profile from star counts over its entire radial extension. We find that the density profile is well reproduced by a single-mass King model with structural parameters c=1.41 and r_c=41". We also studied the Blue Straggler Star population and its radial distribution. We count a total number of 120 BSS within the tidal radius. Their radial distribution is bimodal: highly peaked in the cluster center, decreasing at intermediate distances and rising again outwards. We discuss these results in the context of the dynamical clock scheme presented by Ferraro et al. (2012) and of recent results about the radial distribution of binary systems in this cluster.Comment: Accepted for publication by ApJ; 26 pages, 11 figures, 1 tabl

Rain-induced modification of SAR performance

ABSTRACT The performance degradation suffered by a microwave remote sensing SAR system due to the presence of rain is analysed. In particular, alterations caused by attenuation, backscatter and depolarization due to the presence of a rain cell along a swath is estimated. Furthermore, a global evaluation of the degradation as a function of the rain intensity is carried out by using a proper parameter. Numerical calculations are performed for some typical SAR configurations at 10 GHz; suitable models for the interaction of electromagnetic waves with raindrops are used

Evidence for (and Against) Progenitor Bias in the Size Growth of Compact Red Galaxies

Most massive passive galaxies are compact at high redshifts, but similarly compact massive galaxies are rare in the local universe. The most common interpretation of this phenomenon is that massive galaxies have grown in size by a factor of about five since redshift z=2. An alternative explanation is that recently quenched massive galaxies are larger (a "progenitor bias"). In this paper we explore the importance of progenitor bias by looking for systematic differences in the stellar populations of compact early-type galaxies in the DEEP2 survey as a function of size. Our analysis is based on applying the statistical technique of bootstrap resampling to constrain differences in the median ages of our samples and to begin to characterize the distribution of stellar populations in our co-added spectra. The light-weighted ages of compact early-type galaxies at redshifts 0.5 < z < 1.4 are compared to those of a control sample of larger galaxies at similar redshifts. We find that massive compact early-type galaxies selected on the basis of red color and high bulge-to-total ratio are younger than similarly selected larger galaxies, suggesting that size growth in these objects is not driven mainly by progenitor bias, and that individual galaxies grow as their stellar populations age. However, compact early-type galaxies selected on the basis of image smoothness and high bulge-to-total ratio are older than a control sample of larger galaxies. Progenitor bias will play a significant role in defining the apparent size changes of early-type galaxies if they are selected on the basis of the smoothness of their light distributions.Comment: 39 pages, 10 figures. Astrophysical Journal (in press

Short-term responses to salinity of soybean and chenopodium album grown in single and mixed-species hydroponic systems

Weeds account for losses in crop yields, and this event might be exacerbated by salinity. Therefore, we investigated the responses of Chenopodium album L. and soybean (Glycine max (L.) Merr.) to salt stress, as well as interferences between species. Ten-day old plants were grown for 1 week in a single- or mixed-species set-up, either with or without 100 mM of NaCl. C. album reduced the biomass of soybean similarly to salt stress, while its growth was unaffected under any condition. C. album decreased the crop protein content when salinity was applied. This effect was ascribed to altered protein metabolism and/or N usage to produce other N metabolites, including osmolytes. The two species did not reciprocally affect the capacity to accumulate Na+, but the weed contained two-fold more Na+ in the leaves. Elevated initial K+ concentration and high K+ delivery to the shoot likely explained the better acclimation of C. album to salinity. C. album produced more phenolics and proline and exhibited greater antioxidant activity, but low lipid peroxidation, in the mixed set-up under salinity. Thus, it is possible that the weed could become more resilient to salinity when growing in a soybean field. In the long term, this might cause significant losses in soybean productivity as expected by the dramatic decline in crop protein content

Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca

We present a method for determining mean light-weighted ages and abundances of Fe, Mg, C, N, and Ca, from medium resolution spectroscopy of unresolved stellar populations. The method, pioneered by Schiavon (2007), is implemented in a publicly available code called EZ_Ages. The method and error estimation are described, and the results tested for accuracy and consistency, by application to integrated spectra of well-known Galactic globular and open clusters. Ages and abundances from integrated light analysis agree with studies of resolved stars to within +/-0.1 dex for most clusters, and to within +/-0.2 dex for nearly all cases. The results are robust to the choice of Lick indices used in the fitting to within +/-0.1 dex, except for a few systematic deviations which are clearly categorized. The realism of our error estimates is checked through comparison with detailed Monte Carlo simulations. Finally, we apply EZ_Ages to the sample of galaxies presented in Thomas et al. (2005) and compare our derived values of age, [Fe/H], and [alpha/Fe] to their analysis. We find that [alpha/Fe] is very consistent between the two analyses, that ages are consistent for old (Age > 10 Gyr) populations, but show modest systematic differences at younger ages, and that [Fe/H] is fairly consistent, with small systematic differences related to the age systematics. Overall, EZ_Ages provides accurate estimates of fundamental parameters from medium resolution spectra of unresolved stellar populations in the old and intermediate-age regime, for the first time allowing quantitative estimates of the abundances of C, N, and Ca in these unresolved systems. The EZ_Ages code can be downloaded at http://www.ucolick.org/~graves/EZ_Ages.htmlComment: Accepted to ApJ

An optimal estimator for the CMB-LSS angular power spectrum and its application to WMAP and NVSS data

We use a Quadratic Maximum Likelihood (QML) method to estimate the angular power spectrum of the cross-correlation between cosmic microwave background and large scale structure maps as well as their individual auto-spectra. We describe our implementation of this method and demonstrate its accuracy on simulated maps. We apply this optimal estimator to WMAP 7-year and NRAO VLA Sky Survey (NVSS) data and explore the robustness of the angular power spectrum estimates obtained by the QML method. With the correction of the declination systematics in NVSS, we can safely use most of the information contained in this survey. We then make use of the angular power spectrum estimates obtained by the QML method to derive constraints on the dark energy critical density in a flat $\Lambda$CDM model by different likelihood prescriptions. When using just the cross-correlation between WMAP 7 year and NVSS maps with 1.8$^\circ$ resolution, the best-fit model has a cosmological constant of approximatively 70% of the total energy density, disfavouring an Einstein-de Sitter Universe at more than 2 $\sigma$ CL (confidence level).Comment: 12 pages, 12 figure

A Panchromatic Study of the Globular Cluster NGC 1904. I: The Blue Straggler Population

By combining high-resolution (HST-WFPC2) and wide-field ground based (2.2m ESO-WFI) and space (GALEX) observations, we have collected a multi-wavelength photometric data base (ranging from the far UV to the near infrared) of the galactic globular cluster NGC1904 (M79). The sample covers the entire cluster extension, from the very central regions up to the tidal radius. In the present paper such a data set is used to study the BSS population and its radial distribution. A total number of 39 bright ($m_{218}\le 19.5$) BSS has been detected, and they have been found to be highly segregated in the cluster core. No significant upturn in the BSS frequency has been observed in the outskirts of NGC 1904, in contrast to other clusters (M 3, 47 Tuc, NGC 6752, M 5) studied with the same technique. Such evidences, coupled with the large radius of avoidance estimated for NGC 1904 ($r_{avoid}\sim 30$ core radii), indicate that the vast majority of the cluster heavy stars (binaries) has already sunk to the core. Accordingly, extensive dynamical simulations suggest that BSS formed by mass transfer activity in primordial binaries evolving in isolation in the cluster outskirts represent only a negligible (0--10%) fraction of the overall population.Comment: ApJ accepte