42 research outputs found

    A photoionization model of the spatial distribution of the optical and mid-IR properties in NGC595

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    We present a set of photoionization models that reproduce simultaneously the observed optical and mid-infrared spatial distribution of the HII region NGC595 in the disk of M33 using the code CLOUDY. Both optical (PMAS-Integral Field Spectroscopy) and mid-infrared (8 mi and 24 mi bands from Spitzer) data provide enough spatial resolution to model in a novel approach the inner structure of the HII region. We define a set of elliptical annular regions around the central ionizing cluster with an uniformity in their observed properties and consider each annulus as an independent thin shell structure. For the first time our models fit the relative surface brightness profiles in both the optical (Halpha, [OII], [OIII]) and the mid-infrared emissions (8 mi and 24 mi), under the assumption of a uniform metallicity (12+log(O/H) = 8.45; Esteban et al. 2009) and an age for the stellar cluster of 4.5 Myr (Malumuth et al. 1996). Our models also reproduce the observed uniformity of the R23 parameter and the increase of the [OII]/[OIII] ratio due to the decrease of the ionization parameter. The variation of the Halpha profile is explained in terms of the differences of the occupied volume (the product of filling factor and total volume of the shell) in a matter-bounded geometry, which also allows to reproduce the observed pattern of the extinction. The 8 mi/24 mi ratio is low (ranging between 0.04 and 0.4) because it is dominated by the surviving of small dust grains in the HII region, while the PAHs emit more weakly because they cannot be formed in these thin HII gas shells. The ratio is also well fitted in our models by assuming a dust-to-gas ratio in each annulus compatible with the integrated estimate for the whole HII region after the 70 mi, and 160 mi Spitzer observations.Comment: Accepted for publication in MNRAS, 9 pages, 17 figure

    PopStar Evolutionary Synthesis Models II: Optical emission-line spectra from Giant H{\sc ii} regions

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    This is the second paper of a series reporting the results from the PopStar evolutionary synthesis models. Here we present synthetic emission line spectra of H{\sc ii} regions photoionized by young star clusters, for seven values of cluster masses and for ages between 0.1 and 5.2 Myr. The ionizing Spectral Energy Distributions (SEDs) are those obtained by the PopStar code \citep*{mgb09} for six different metallicities, with a very low metallicity set, Z=0.0001, not included in previous similar works. We assume that the radius of the H{\sc ii} region is the distance at which the ionized gas is deposited by the action of the mechanical energy of the winds and supernovae from the central ionizing young cluster. In this way the ionization parameter is eliminated as free argument, since now its value is obtained from the cluster physical properties (mass, age and metallicity) and from the gaseous medium characteristics (density and abundances). We discuss our results and compare them with those from previous models and also with a large and data set of giant H{\sc ii} regions for which abundances have been derived in a homogeneous manner. The values of the [OIII] lines (at λλ\lambda\lambda 4363, 4959, 5007\AA) in the lowest metallicity nebulae are found to be very weak and similar to those coming from very high metallicity regions (solar or over-solar). Thus, the sole use of the oxygen lines is not enough to distinguish between very low and very high metallicity regions. In these cases we emphasize the need of the additional support of alternative metallicity tracers, like the [SIII] lines in the near-\textit{IR}.Comment: 20 pages, 26 figures, accepted for publication in MNRAS Main Journa

    Impacto de la variabilidad intrapaciente en la concentración sanguínea de anticalcineurínicos en los resultados del trasplante cardiaco

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    [Abstract] Introduction and objectives. Intrapatient blood level variability (IPV) of calcineurin inhibitors has been associated with poor outcomes in solid-organ transplant, but data for heart transplant are scarce. Our purpose was to ascertain the clinical impact of IPV in a multi-institutional cohort of heart transplant recipients. Methods. We retrospectively studied patients aged ≥ 18 years, with a first heart transplant performed between 2000 and 2014 and surviving ≥ 1 year. IPV was assessed by the coefficient of variation of trough levels from posttransplant months 4 to 12. A composite of rejection or mortality/graft loss or rejection and all-cause mortality/graft loss between years 1 to 5 posttransplant were analyzed by Cox regression analysis. Results. The study group consisted of 1581 recipients (median age, 56 years; women, 21%). Cyclosporine immediate-release tacrolimus and prolonged-release tacrolimus were used in 790, 527 and 264 patients, respectively. On multivariable analysis, coefficient of variation > 27.8% showed a nonsignificant trend to association with 5-year rejection-free survival (HR, 1.298; 95%CI, 0.993-1.695; P = .056) and with 5-year mortality (HR, 1.387; 95%CI, 0.979-1.963; P = .065). Association with rejection became significant on analysis of only those patients without rejection episodes during the first year posttransplant (HR, 1.609; 95%CI, 1.129-2.295; P = .011). The tacrolimus-based formulation had less IPV than cyclosporine and better results with less influence of IPV. Conclusions. IPV of calcineurin inhibitors is only marginally associated with mid-term outcomes after heart transplant, particularly with the tacrolimus-based immunosuppression, although it could play a role in the most stable recipients.[Resumen] Introducción y objetivos. El objetivo es estudiar el impacto clínico de la variabilidad intrapaciente (VIP) de la concentración sanguínea de los anticalcineurínicos en el trasplante cardiaco, pues la información actual es escasa. Métodos. Se analizó retrospectivamente a pacientes de edad ≥ 18 años con un trasplante cardiaco realizado entre 2000 y 2014 y con supervivencia ≥ 1 año. La VIP se valoró mediante el coeficiente de variación de concentraciones entre los meses 4 a 12 postrasplante. El compuesto de rechazo, mortalidad o pérdida del injerto y la mortalidad o pérdida del injerto 1-5 años tras el trasplante se analizaron mediante regresión de Cox. Resultados. Se estudió a 1.581 receptores (edad, 56 años; mujeres, 21%), tratados con ciclosporina (790 pacientes) o tacrolimus (791 pacientes). En el análisis multivariable, un coeficiente de variación > 27,8% tendió a asociarse con el compuesto de rechazo/mortalidad (HR = 1,298; IC95%, 0,993-1,695; p = 0,056) y con la mortalidad (HR = 1,387; IC95%, 0,979-1,963; p = 0,065) a los 5 años. La asociación con el rechazo fue significativa al analizar a la población sin rechazos durante el primer año del trasplante (HR = 1,609; IC95%, 1,129-2,295; p = 0,011). El tacrolimus tuvo menos VIP que la ciclosporina, junto con unos mejores resultados por la menor influencia de la VIP. Conclusiones. La VIP de los anticalcineurínicos, especialmente con la inmunosupresión basada en el tacrolimus, se asocia solo marginalmente con los resultados a medio plazo del trasplante cardiaco, aunque puede tener influencia en los pacientes más estables durante el primer año tras el trasplante

    Eliminating Error in the Chemical Abundance Scale for Extragalactic HII Regions

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    In an attempt to remove the systematic errors which have plagued the calibration of the HII region abundance sequence, we have theoretically modeled the extragalactic HII region sequence. We then used the theoretical spectra so generated in a double blind experiment to recover the chemical abundances using both the classical electron temperature + ionization correction factor technique, and the technique which depends on the use of strong emission lines (SELs) in the nebular spectrum to estimate the abundance of oxygen. We find a number of systematic trends, and we provide correction formulae which should remove systematic errors in the electron temperature + ionization correction factor technique. We also provide a critical evaluation of the various semi-empirical SEL techniques. Finally, we offer a scheme which should help to eliminate systematic errors in the SEL-derived chemical abundance scale for extragalactic HII regions.Comment: 24 pages, 9 Tables, 13 figures, accepted for publication in MNRAS. Updated considering minor changes during the final edition process and some few missing reference

    The miniJPAS survey. Evolution of the luminosity and stellar mass functions of galaxies up to z0.7z \sim 0.7

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    We aim at developing a robust methodology for constraining the luminosity and stellar mass functions (LMFs) of galaxies by solely using data from multi-filter surveys and testing the potential of these techniques for determining the evolution of the miniJPAS LMFs up to z0.7z\sim0.7. Stellar mass and BB-band luminosity for each of the miniJPAS galaxies are constrained using an updated version of the SED-fitting code MUFFIT, whose values are based on composite stellar population models and the probability distribution functions of the miniJPAS photometric redshifts. Galaxies are classified through the stellar mass versus rest-frame colour diagram corrected for extinction. Different stellar mass and luminosity completeness limits are set and parametrised as a function of redshift, for setting limits in our flux-limited sample (rSDSS<22r_\mathrm{SDSS}<22). The miniJPAS LMFs are parametrised according to Schechter-like functions via a novel maximum likelihood method accounting for uncertainties, degeneracies, probabilities, completeness, and priors. Overall, our results point to a smooth evolution with redshift (0.05<z<0.70.05<z<0.7) of the miniJPAS LMFs in agreement with previous work. The LMF evolution of star-forming galaxies mainly involve the bright and massive ends of these functions, whereas the LMFs of quiescent galaxies also exhibit a non-negligible evolution on their faint and less massive ends. The cosmic evolution of the global BB-band luminosity density decreases ~0.1 dex from z=0.7z=0.7 to 0, whereas for quiescent galaxies this quantity roughly remains constant. In contrast, the stellar mass density increases ~0.3 dex at the same redshift range, where such evolution is mainly driven by quiescent galaxies owing to an overall increasing number of this kind of galaxies, which in turn includes the majority and most massive galaxies (60-100% fraction of galaxies at log10(M/M)>10.7\log_{10}(M_\star/M_\odot)>10.7).Comment: 31 pages, 15 figures. Submitted to A&

    The miniJPAS survey:star-galaxy classification using machine learning

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    Future astrophysical surveys such as J-PAS will produce very large datasets, which will require the deployment of accurate and efficient Machine Learning (ML) methods. In this work, we analyze the miniJPAS survey, which observed about 1 deg2 of the AEGIS field with 56 narrow-band filters and 4 ugri broad-band filters. We discuss the classification of miniJPAS sources into extended (galaxies) and point-like (e.g. stars) objects, a necessary step for the subsequent scientific analyses. We aim at developing an ML classifier that is complementary to traditional tools based on explicit modeling. In order to train and test our classifiers, we crossmatched the miniJPAS dataset with SDSS and HSC-SSP data. We trained and tested 6 different ML algorithms on the two crossmatched catalogs. As input for the ML algorithms we use the magnitudes from the 60 filters together with their errors, with and without the morphological parameters. We also use the mean PSF in the r detection band for each pointing. We find that the RF and ERT algorithms perform best in all scenarios. When analyzing the full magnitude range of 1521). We use our best classifiers, with and without morphology, in order to produce a value added catalog available at https://j-pas.org/datareleases

    Risk factors associated with moderate-to-severe renal dysfunction among heart transplant patients: results from the CAPRI study

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    [Abstract] The longer survival of patients with heart transplantation (HT) favors calcineurin inhibitor–related chronic kidney disease (CKD). It behoves to identify risk factors. At 14 Spanish centers, data on 1062 adult patients with HT (age 59.2 ± 12.3 yr, 82.5% men) were collected at routine follow-up examinations. Glomerular filtration rate, GFR, was estimated using the four-variable MDRD equation, and moderate-or-severe renal dysfunction (MSRD) was defined as K/DOQI stage 3 CKD or worse. Time since transplant ranged from one month to 22 yr (mean 6.7 yr). At assessment, 26.6% of patients were diabetic and 63.9% hypertensive; 53.9% were taking cyclosporine and 33.1% tacrolimus; and 61.4% had MSRD. Among patients on cyclosporine or tacrolimus at assessment, multivariate logistic regression identified male sex (OR 0.44), pre- and post-HT creatinine (2.73 and 3.13 per mg/dL), age at transplant (1.06 per yr), time since transplant (1.05 per yr), and tacrolimus (0.65) as independent positive or negative predictors of MSRD. It is concluded that female sex, pre- and one-month post-HT serum creatinine, age at transplant, time since transplant, and immunosuppression with cyclosporine rather than tacrolimus may all be risk factors for development of CKD ≥ stage 3 by patients with HT

    The miniJPAS survey: clusters and galaxy groups detection with AMICO

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    Samples of galaxy clusters allow us to better understand the physics at play in galaxy formation and to constrain cosmological models once their mass, position (for clustering studies) and redshift are known. In this context, large optical data sets play a crucial role. We investigate the capabilities of the Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) in detecting and characterizing galaxy groups and clusters. We analyze the data of the miniJPAS survey, obtained with the JPAS-Pathfinder camera and covering 11 deg2^2 centered on the AEGIS field to the same depths and with the same 54 narrow band plus 2 broader band near-UV and near-IR filters anticipated for the full J-PAS survey. We use the Adaptive Matched Identifier of Clustered Objects (AMICO) to detect and characterize groups and clusters of galaxies down to S/N=2.5S/N=2.5 in the redshift range 0.05<z<0.80.05<z<0.8. We detect 80, 30 and 11 systems with signal-to-noise ratio larger than 2.5, 3.0 and 3.5, respectively, down to 1013M/h\sim 10^{13}\,M_{\odot}/h. We derive mass-proxy scaling relations based on Chandra and XMM-Newton X-ray data for the signal amplitude returned by AMICO, the intrinsic richness and a new proxy that incorporates the galaxies' stellar masses. The latter proxy is made possible thanks to the J-PAS filters and shows a smaller scatter with respect to the richness. We fully characterize the sample and use AMICO to derive a probabilistic membership association of galaxies to the detected groups that we test against spectroscopy. We further show how the narrow band filters of J-PAS provide a gain of up to 100% in signal-to-noise ratio in detection and an uncertainty on the redshift of clusters of only σz=0.0037(1+z)\sigma_z=0.0037(1+z) placing J-PAS in between broadband photometric and spectroscopic surveys. The performances of AMICO and J-PAS with respect to mass sensitivity, mass-proxies qualityComment: 15 pages, 12 figures, 3 tables, submitted to A&

    J-NEP: 60-band photometry and photometric redshifts for the James Webb Space Telescope North Ecliptic Pole Time-Domain Field

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    The J-PAS survey will observe ~1/3 of the northern sky with a set of 56 narrow-band filters using the dedicated 2.55 m JST telescope at the Javalambre Astrophysical Observatory. Prior to the installation of the main camera, in order to demonstrate the scientific potential of J-PAS, two small surveys were performed with the single-CCD Pathfinder camera: miniJPAS (~1 deg2 along the Extended Groth Strip), and J-NEP (~0.3 deg2 around the JWST North Ecliptic Pole Time Domain Field), including all 56 J-PAS filters as well as u, g, r, and i. J-NEP is ~0.5-1.0 magnitudes deeper than miniJPAS, providing photometry for 24,618 r-band detected sources and photometric redshifts (photo-z) for the 6,662 sources with r<23. In this paper we describe the photometry and photo-z of J-NEP and demonstrate a new method for the removal of systematic offsets in the photometry based on the median colours of galaxies, dubbed "galaxy locus recalibration". This method does not require spectroscopic observations except in a few reference pointings and, unlike previous methods, is applicable to the whole J-PAS survey. We use a spectroscopic sample of 787 galaxies to test the photo-z performance for J-NEP and in comparison to miniJPAS. We find that the deeper J-NEP observations result in a factor ~1.5-2 decrease in sigma_NMAD (a robust estimate of the standard deviation of the photo-z error) and the outlier rate relative to miniJPAS for r>21.5 sources, but no improvement in brighter ones. We find the same relation between sigma_NMAD and odds in J-NEP and miniJPAS, suggesting sigma_NMAD can be predicted for any set of J-PAS sources from their odds distribution alone, with no need for additional spectroscopy to calibrate the relation. We explore the causes for photo-z outliers and find that colour-space degeneracy at low S/N, photometry artifacts, source blending, and exotic spectra are the most important factors.Comment: 16 pages, 25 figures, accepted for publication in Astronomy and Astrophysic

    The miniJPAS & J-NEP surveys: Identification and characterization of the Lyα\alpha Emitter population and the Lyα\alpha Luminosity Function

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    We present the Lyman-aa (Lya) Luminosity Function (LF) at 2.05<z<3.752.05<z<3.75, estimated from a sample of 67 Lya-emitter (LAE) candidates in the J-PAS Pathfinder surveys: miniJPAS and J-NEP. These two surveys cover a total effective area of 1.14\sim 1.14 deg2^2 with 54 Narrow Band (NB) filters across the optical range, with typical limiting magnitudes of 23\sim 23. This set of NBs allows to probe Lya emission in a wide and continuous range of redshifts. We develop a method for detecting Lya emission for the estimation of the Lya LF using the whole J-PAS filter set. We test this method by applying it to the miniJPAS and J-NEP data. In order to compute the corrections needed to estimate the Lya LF and to test the performance of the candidates selection method, we build mock catalogs. These include representative populations of Lya Emitters at 1.9<z<4.51.9<z<4.5 as well as their expected contaminants, namely low-zz galaxies and z<2z<2 QSOs. We show that our method is able to provide the Lya LF at the intermediate-bright range of luminosity (1043.5ergs1LLya1044.5ergs1\rm 10^{43.5} erg\,s^{-1} \lesssim L_{Lya} \lesssim 10^{44.5} erg\,s^{-1}). The photometric information provided by these surveys suggests that our samples are dominated by bright, Lya-emitting Active Galactic Nuclei. At LLya<1044.5L_{{\rm Ly}a}<10^{44.5} erg\,s1^{-1}, we fit our Lya LF to a power-law with slope A=0.70±0.25A=0.70\pm0.25. We also fit a Schechter function to our data, obtaining: Log(\Phi^* / \text{Mpc^{-3}})=-6.30^{+0.48}_{-0.70}, Log(L/ergs1)=44.850.32+0.50(L^*/ \rm erg\,s^{-1})=44.85^{+0.50}_{-0.32}, a=1.650.27+0.29a=-1.65^{+0.29}_{-0.27}. Overall, our results confirm the presence of an AGN component at the bright-end of the Lya LF. In particular, we find no significant contribution of star-forming LAEs to the Lya LF at Log(LLya(L_{\rm Lya} / erg\,s1^{-1})>43.5. This work serves as a proof-of-concept for the results that can be obtained with the upcoming data releases of the J-PAS survey.Comment: 25 pages, 15 figures, submitted to A&
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