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The Gaia-ESO Survey: metallicity and kinematic trends in the Milky Way bulge

Titulo: 
The Gaia-ESO Survey: metallicity and kinematic trends in the Milky Way bulge
Autores: 
Rojas-Arriagada, A; Recio-Blanco, A; Hill, V; de Laverny, P; Schultheis, M; Babusiaux, C; Zoccali, M; Minniti, D; Gonzalez, OA; Feltzing, S; Gilmore, G; Randich, S; Vallenari, A; Alfaro, EJ; Bensby, T; Bragaglia, A; Flaccomio, E; Lanzafame, AC; Pancino, E; Smiljanic, R; Bergemann, M; Costado, MT; Damiani, F; Hourihane, A; Jofre, P; Lardo, C; Magrini, L; Maiorca, E; Morbidelli, L; Sbordone, L; Worley, CC; Zaggia, S; Wyse, R
Resumen: 
Aims. Observational studies of the Milky Way bulge are providing increasing evidence of its complex chemo-dynamical patterns and morphology. Our intent is to use the iDR1 Gaia-ESO Survey (GES) data set to provide new constraints on the metallicity and kinematic trends of the Galactic bulge, exploring the viability of the currently proposed formation scenarios. Methods. We analyzed the stellar parameters and radial velocities of similar to 1200 stars in five bulge fields wich are located in the region -10 degrees < / < 7 degrees and -10 degrees < b < -4 degrees. We use VISTA Variables in the Via Lactea (VVV) photometry to verify the internal consistency of the atmospheric parameters recommended by the consortium. As a by-product, we obtained reddening values using a semi-empirical Tdf -color calibration. We constructed the metallicity distribution functions and combined them with photometric and radial velocity data to analyze the properties of the stellar populations in the observed fields. Results. From a Gaussian decomposition of the metallicity distribution functions, we unveil a clear bimodality in all fields, with the relative size of components depending of the specific position on the sky. In agreement with some previous studies, we find a mild gradient along the minor axis (-0.05 dex/deg between b = -6 degrees and b = -10 degrees) that arises from the varying proportion of metal-rich and metal-poor components. The number of metal-rich stars fades in favor of the metal-poor stars with increasing b. The K-magnitude distribution of the metal-rich population splits into two peaks for two of the analyzed fields that intersects the near and far branches of the X-shaped bulge structure. In addition, two lateral fields at (l,b) = (7, -9) and (l, b) = (-10, 8) present contrasting characteristics. In the former, the metallicity distribution is dominated by metal-rich stars, while in the latter it presents a mix of a metal-poor population and and a metal-intermediate one, of nearly equal sizes. Finally, we find systematic differences in the velocity dispersion between the metal-rich and the metal-poor components of each field. Conclusions. The iDR I bulge data show chemo-dynamical distributions that are consistent with varying proportions of stars belonging to (i) a metal-rich boxy/peanut X-shaped component, with bar-like kinematics; and (ii) a metal-poor more extended rotating structure with a higher velocity dispersion that dominates far from the Galactic plane. These first GES data already allow studying the detailed spatial dependence of the Galactic bulge populations, thanks to the analysis of individual fields with relatively high statistics.
Autor principal: 
Rojas-Arriagada, A
Autor/es del IAA: 
Alfaro, E. J.; Costado, M. T.
DOI: 
10.1051/0004-6361/201424121
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/09
Volumen: 
569
Tipo de documento: 
Article
Palabras clave: 
Galaxy: formation; Galaxy: abundances; Galaxy: bulge; Galaxy: stellar content; stars: abundances
Número de artículo: 
A103

Rotational properties of the binary and non-binary populations in the trans-Neptunian belt

Titulo: 
Rotational properties of the binary and non-binary populations in the trans-Neptunian belt
Autores: 
Thirouin, A; Noll, KS; Ortiz, JL; Morales, N
Resumen: 
We present results for the short-term variability of binary trans-Neptunian objects (BTNOs). We performed CCD photometric observations using the 3.58 m Telescopio Nazionale Galileo (TNG), the 1.5 m Sierra Nevada Observatory (OSN) telescope, and the 1.23 m Centro Astronomico Hispano Aleman (CAHA) telescope at Calar Alto Observatory. We present results based on five years of observations and report the short-term variability of six BTNOs. Our sample contains three classical objects: (174567) 2003 MW12, or Varda, (120347) 2004 SB60, or Salacia, and 2002 VT130; one detached disk object: (229762) 2007 UK126; and two resonant objects: (341520) 2007 TY430 and (38628) 2000 EB173, or Huya. For each target, possible rotational periods and/or photometric amplitudes are reported. We also derived some physical properties from their light curves, such as density, primary and secondary sizes, and albedo. We compiled and analyzed a vast light curve database for TNOs including centaurs to determine the light-curve amplitude and spin frequency distributions for the binary and non-binary populations. The mean rotational periods, from the Maxwellian fits to the frequency distributions, are 8.63 +/- 0.52 h for the entire sample, 8.37 +/- 0.58 h for the sample without the binary population, and 10.11 +/- 1.19 h for the binary population alone. Because the centaurs are collisionally more evolved, their rotational periods might not be so primordial. We computed a mean rotational period, from the Maxwellian fit, of 8.86 +/- 0.58 h for the sample without the centaur population, and of 8.64 +/- 0.67 h considering a sample without the binary and the centaur populations. According to this analysis, regular TNOs spin faster than binaries, which is compatible with the tidal interaction of the binaries. Finally, we examined possible formation models for several systems studied in this work and by our team in previous papers.
Autor principal: 
Thirouin, A
Autor/es del IAA: 
Thirouin, A.; Ortiz, J. L.; Morales, N.
DOI: 
10.1051/0004-6361/201423567
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/09
Volumen: 
569
Tipo de documento: 
Article
Palabras clave: 
planetary systems; Kuiper belt: general; techniques: photometric
Número de artículo: 
A3

CALIFA: a diameter-selected sample for an integral field spectroscopy galaxy survey

Titulo: 
CALIFA: a diameter-selected sample for an integral field spectroscopy galaxy survey
Autores: 
Walcher, CJ; Wisotzki, L; Bekeraite, S; Husemann, B; Iglesias-Paramo, J; Backsmann, N; Ballesteros, JB; Catalan-Torrecilla, C; Cortijo, C; del Olmo, A; Lorenzo, BG; Falcon-Barroso, J; Jilkova, L; Kalinova, V; Mast, D; Marino, RA; Mendez-Abreu, J; Pasquali, A; Sanchez, SF; Trager, S; Zibetti, S; Aguerri, JAL; Alves, J; Bland-Hawthorn, J; Boselli, A; Morales, AC; Fernandes, RC; Flores, H; Galbany, L; Gallazzi, A; Garcia-Benito, R; de Paz, AG; Gonzalez-Delgado, RM; Jahnke, K; Jungwiert, B; Kehrig, C; Lyubenova, M; Perez, IM; Masegosa, J; Ibero, AM; Perez, E; Quirrenbach, A; Rosales-Ortega, FF; Roth, MM; Sanchez-Blazquez, P; Spekkens, K; Tundo, E; van de Ven, G; Verheijen, MAW; Vilchez, JV; Ziegler, B
Resumen: 
We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA 'mother sample' was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45 '' and 79 : 2 '' and with a redshift 0 : 005 < z < 0 : 03. The mother sample contains 939 objects, 600 of which will be observed in the course of the CALIFA survey. The selection of targets for observations is based solely on visibility and thus keeps the statistical properties of the mother sample. By comparison with a large set of SDSS galaxies, we find that the CALIFA sample is representative of galaxies over a luminosity range of -19 > M-r > -23 : 1 and over a stellar mass range between 10(9.7) and 10(11.4) M-circle dot. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of M-r = -19 (or stellar masses < 10(9.7) M-circle dot) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form < 10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies, finding that the sample covers environmental conditions from the field to genuine clusters. We finally consider the expected incidence of active galactic nuclei among CALIFA galaxies given the existing pre-CALIFA data, finding that the final observed CALIFA sample will contain approximately 30 Sey2 galaxies.
Autor principal: 
Walcher, CJ
Autor/es del IAA: 
Iglesias-Paramo, J.; Cortijo, C.; del Olmo, A.; Sanchez, S. F.; Garcia-Benito, R.; Gonzalez-Delgado, R. M.; Kehrig, C.; Marquez Perez, I.; Masegosa, J.; Perez, E.; Vilchez, J. V.
DOI: 
10.1051/0004-6361/201424198
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/09
Volumen: 
569
Tipo de documento: 
Article
Palabras clave: 
surveys
Número de artículo: 
A1

A CENSUS OF STAR-FORMING GALAXIES IN THE Z similar to 9-10 UNIVERSE BASED ON HST plus SPITZER OBSERVATIONS OVER 19 CLASH CLUSTERS: THREE CANDIDATE Z similar to 9-10 GALAXIES AND IMPROVED CONSTRAINTS ON THE STAR FORMATION RATE DENSITY AT Z similar to 9.2

Titulo: 
A CENSUS OF STAR-FORMING GALAXIES IN THE Z similar to 9-10 UNIVERSE BASED ON HST plus SPITZER OBSERVATIONS OVER 19 CLASH CLUSTERS: THREE CANDIDATE Z similar to 9-10 GALAXIES AND IMPROVED CONSTRAINTS ON THE STAR FORMATION RATE DENSITY AT Z similar to 9.2
Autores: 
Bouwens, RJ; Bradley, L; Zitrin, A; Coe, D; Franx, M; Zheng, W; Smit, R; Host, O; Postman, M; Moustakas, L; Labbe, I; Carrasco, M; Molino, A; Donahue, M; Kelson, DD; Meneghetti, M; Benttez, N; Lemze, D; Umetsu, K; Broadhurst, T; Moustakas, J; Rosati, P; Jouvel, S; Bartelmann, M; Ford, H; Graves, G; Grillo, C; Infante, L; Jimenez-Teja, Y; Lahav, O; Maoz, D; Medezinski, E; Melchior, P; Merten, J; Nonino, M; Ogaz, S; Seitz, S
Resumen: 
We utilize a two-color Lyman-break selection criterion to search for z similar to 9-10 galaxies over the first 19 clusters in the CLASH program. A systematic search yields three z similar to 9-10 candidates. While we have already reported the most robust of these candidates, MACS1149-JD, two additional z similar to 9 candidates are also found and have H-160- band magnitudes of similar to 26.2-26.9. A careful assessment of various sources of contamination suggests less than or similar to 1 contaminants for our z similar to 9-10 selection. To determine the implications of these search results for the luminosity function (LF) and star formation rate density at z similar to 9, we introduce a new differential approach to deriving these quantities in lensing fields. Our procedure is to derive the evolution by comparing the number of z similar to 9-10 galaxy candidates found in CLASH with the number of galaxies in a slightly lower-redshift sample (after correcting for the differences in selection volumes), here taken to be z similar to 8. This procedure takes advantage of the fact that the relative volumes available for the z similar to 8 and z similar to 9-10 selections behind lensing clusters are not greatly dependent on the details of the lensing models. We find that the normalization of the UV LF at z similar to 9 is just 0.28(-0.20)(+0.39) x that at z similar to 8, which is similar to 1.4(-0.8)(+3.0) x lower than extrapolating z similar to 4-8 LF results. While consistent with the evolution in the UV LF seen at z similar to 4-8, these results marginally favor a more rapid evolution at z > 8. Compared to similar evolutionary findings from the HUDF, our result is less insensitive to large-scale structure uncertainties, given our many independent sightlines on the high-redshift universe.
Autor principal: 
Bouwens, RJ
Autor/es del IAA: 
Molino, A.; Jimenez-Teja, Y.
DOI: 
10.1088/0004-637X/795/2/126
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/11/10
Volumen: 
795
Issue: 
2
Tipo de documento: 
Article
Palabras clave: 
galaxies: evolution; galaxies: high-redshift
Número de artículo: 
126

CLASH: WEAK-LENSING SHEAR-AND-MAGNIFICATION ANALYSIS OF 20 GALAXY CLUSTERS

Titulo: 
CLASH: WEAK-LENSING SHEAR-AND-MAGNIFICATION ANALYSIS OF 20 GALAXY CLUSTERS
Autores: 
Umetsu, K; Medezinski, E; Nonino, M; Merten, J; Postman, M; Meneghetti, M; Donahue, M; Czakon, N; Molino, A; Seitz, S; Gruen, D; Lemze, D; Balestra, I; Benitez, N; Biviano, A; Broadhurst, T; Ford, H; Grillo, C; Koekemoer, A; Melchior, P; Mercurio, A; Moustakas, J; Rosati, P; Zitrin, A
Resumen: 
We present a joint shear-and-magnification weak-lensing analysis of a sample of 16 X-ray-regular and 4 high-magnification galaxy clusters at 0.19 less than or similar to z less than or similar to 0.69 selected from the Cluster Lensing And Supernova survey with Hubble (CLASH). Our analysis uses wide-field multi-color imaging, taken primarily with Suprime-Cam on the Subaru Telescope. From a stacked-shear-only analysis of the X-ray-selected subsample, we detect the ensemble-averaged lensing signal with a total signal-to-noise ratio of similar or equal to 25 in the radial range of 200-3500 kpc h(-1), providing integrated constraints on the halo profile shape and concentration-mass relation. The stacked tangential-shear signal is well described by a family of standard density profiles predicted for dark-matter-dominated halos in gravitational equilibrium, namely, the Navarro-Frenk-White (NFW), truncated variants of NFW, and Einasto models. For the NFW model, we measure a mean concentration of c(200c) = 4.01(-0.32)(+0.35) at an effective halo mass of M-200c = 1.34(-0.09)(+0.10) x 10(15) M-circle dot. We show that this is in excellent agreement with. cold dark matter (Lambda CDM) predictions when the CLASH X-ray selection function and projection effects are taken into account. The best-fit Einasto shape parameter is alpha(E) = 0.191(-0.068)(+0.071), which is consistent with the NFW-equivalent Einasto parameter of similar to 0.18. We reconstruct projected mass density profiles of all CLASH clusters from a joint likelihood analysis of shear-and-magnification data and measure cluster masses at several characteristic radii assuming an NFW density profile. We also derive an ensemble-averaged total projected mass profile of the X-ray-selected subsample by stacking their individual mass profiles. The stacked total mass profile, constrained by the shear+magnification data, is shown to be consistent with our shear-based halo-model predictions, including the effects of surrounding large-scale structure as a two-halo term, establishing further consistency in the context of the Lambda CDM model.
Autor principal: 
Umetsu, K
Autor/es del IAA: 
Molino, Alberto; Benitez, Narciso
DOI: 
10.1088/0004-637X/795/2/163
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/11/10
Volumen: 
795
Issue: 
2
Tipo de documento: 
Article
Palabras clave: 
cosmology: observations; dark matter; galaxies: clusters: general; gravitational lensing: weak
Número de artículo: 
163

VERIFICATION OF THE ASTROMETRIC PERFORMANCE OF THE KOREAN VLBI NETWORK, USING COMPARATIVE SFPR STUDIES WITH THE VLBA AT 14/7 mm

Titulo: 
VERIFICATION OF THE ASTROMETRIC PERFORMANCE OF THE KOREAN VLBI NETWORK, USING COMPARATIVE SFPR STUDIES WITH THE VLBA AT 14/7 mm
Autores: 
Rioja, MJ; Dodson, R; Jung, T; Sohn, BW; Byun, DY; Agudo, I; Cho, SH; Lee, SS; Kim, J; Kim, KT; Oh, CS; Han, ST; Je, DH; Chung, MH; Wi, SO; Kang, J; Lee, JW; Chung, H; Kim, HR; Kim, HG; Lee, CH; Roh, DG; Oh, SJ; Yeom, JH; Song, MG; Kang, YW
Resumen: 
The Korean VLBI Network (KVN) is a new millimeter VLBI dedicated array with the capability to simultaneously observe at multiple frequencies, up to 129 GHz. The innovative multi-channel receivers present significant benefits for astrometric measurements in the frequency domain. The aim of this work is to verify the astrometric performance of the KVN using a comparative study with the VLBA, a well-established instrument. For that purpose, we carried out nearly contemporaneous observations with the KVN and the VLBA, at 14/7 mm, in 2013 April. The KVN observations consisted of simultaneous dual frequency observations, while the VLBA used fast frequency switching observations. We used the Source Frequency Phase Referencing technique for the observational and analysis strategy. We find that having simultaneous observations results in superior compensation for all atmospheric terms in the observables, in addition to offering other significant benefits for astrometric analysis. We have compared the KVN astrometry measurements to those from the VLBA. We find that the structure blending effects introduce dominant systematic astrometric shifts, and these need to be taken into account. We have tested multiple analytical routes to characterize the impact of the low-resolution effects for extended sources in the astrometric measurements. The results from the analysis of the KVN and full VLBA data sets agree within 2 sigma of the thermal error estimate. We interpret the discrepancy as arising from the different resolutions. We find that the KVN provides astrometric results with excellent agreement, within 1 sigma, when compared to a VLBA configuration that has a similar resolution. Therefore, this comparative study verifies the astrometric performance of the KVN using SFPR at 14/7 mm, and validates the KVN as an astrometric instrument.
Autor principal: 
Rioja, MJ
Autor/es del IAA: 
Agudo, Ivan
DOI: 
10.1088/0004-6256/148/5/84
Revista: 
ASTRONOMICAL JOURNAL
Fecha de publicación: 
2014/11
Volumen: 
148
Issue: 
5
Tipo de documento: 
Article
Palabras clave: 
astrometry; quasars: individual (OJ287, 0854+213); techniques: interferometric
Número de artículo: 
84

Building galaxies, stars, planets and the ingredients for life between the stars. The science behind the European Ultraviolet-Visible Observatory

Titulo: 
Building galaxies, stars, planets and the ingredients for life between the stars. The science behind the European Ultraviolet-Visible Observatory
Autores: 
de Castro, AIG; Appourchaux, T; Barstow, MA; Barthelemy, M; Baudin, F; Benetti, S; Blay, P; Brosch, N; Bunce, E; de Martino, D; Deharveng, JM; Ferlet, R; France, K; Garcia, M; Gansicke, B; Gry, C; Hillenbrand, L; Josselin, E; Kehrig, C; Lamy, L; Lapington, J; des Etangs, AL; LePetit, F; Lopez-Santiago, J; Milliard, B; Monier, R; Naletto, G; Naze, Y; Neiner, C; Nichols, J; Orio, M; Pagano, I; Peroux, C; Rauw, G; Shore, S; Spaans, M; Tovmassian, G; Ud-Doula, A; Vilchez, J
Resumen: 
This contribution gathers the contents of the white paper submitted by the UV community to the Call issued by the European Space Agency in March 2013, for the definition of the L2 and L3 missions in the ESA science program. We outlined the key science that a large UV facility would make possible and the instrumentation to be implemented. The growth of luminous structures and the building blocks of life in the Universe began as primordial gas was processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 -3000 ) spectral range that is unobservable from the ground. A versatile space observatory with UV sensitivity a factor of 50-100 greater than existing facilities will revolutionize our understanding of the Universe. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the star-disk interaction that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field, providing unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Earth's atmosphere is in constant interaction with the interplanetary medium and the solar UV radiation field. A 50-100 times improvement in sensitivity would enable the observation of the key atmospheric ingredients of Earth-like exoplanets (carbon, oxygen, ozone), provide crucial input for models of biologically active worlds outside the solar system, and provide the phenomenological baseline to understand the Earth atmosphere in context.
Autor principal: 
de Castro, AIG
Autor/es del IAA: 
Kehrig, Carolina; Vilchez, Jose
DOI: 
10.1007/s10509-014-1942-7
Revista: 
ASTROPHYSICS AND SPACE SCIENCE
Fecha de publicación: 
2014/11
Volumen: 
354
Issue: 
1
Páginas: 
229-246
Tipo de documento: 
Article
Palabras clave: 
Ultraviolet: general; Ultraviolet: galaxies; Ultraviolet: stars; Ultraviolet: ISM; Ultraviolet: solar

THE HOST GALAXY OF THE GAMMA-RAY NARROW-LINE SEYFERT 1 GALAXY 1H 0323+342

Titulo: 
THE HOST GALAXY OF THE GAMMA-RAY NARROW-LINE SEYFERT 1 GALAXY 1H 0323+342
Autores: 
Tavares, JL; Kotilainen, J; Chavushyan, V; Anorve, C; Puerari, I; Cruz-Gonzalez, I; Patino-Alvarez, V; Anton, S; Carraminana, A; Carrasco, L; Guichard, J; Karhunen, K; Olguin-Iglesias, A; Sanghvi, J; Valdes, J
Resumen: 
We present optical and near-infrared (NIR) imaging data of the radio-loud, narrow-line Seyfert 1 galaxy 1H 0323+342, which shows intense and variable gamma-ray activity discovered by the Fermi satellite with the Large Area Telescope. Near-infrared and optical images are used to investigate the structural properties of the host galaxy of 1H 0323+342; this together with optical spectroscopy allows us to examine its black hole mass. Based on two-dimensional (2D) multiwavelength surface-brightness modeling, we find that statistically, the best model fit is a combination of a nuclear component and a Sersic profile (n similar to 2.8). However, the presence of a disk component (with a small bulge n similar to 1.2) also remains a possibility and cannot be ruled out with the present data. Although at first glance a spiral-arm-like structure is revealed in our images, a 2D Fourier analysis of the imagery suggests that this structure corresponds to an asymmetric ring, likely associated with a recent violent dynamical interaction. We discuss our results in the context of relativistic jet production and galaxy evolution.
Autor principal: 
Tavares, JL
Autor/es del IAA: 
Anton, S.
DOI: 
10.1088/0004-637X/795/1/58
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/11/01
Volumen: 
795
Issue: 
1
Tipo de documento: 
Article
Palabras clave: 
galaxies: evolution; galaxies: individual (1H 0323+342); galaxies: interactions; galaxies: jets; galaxies: Seyfert; gamma rays: galaxies
Número de artículo: 
58

YOUNG GALAXY CANDIDATES IN THE HUBBLE FRONTIER FIELDS. I. A2744

Titulo: 
YOUNG GALAXY CANDIDATES IN THE HUBBLE FRONTIER FIELDS. I. A2744
Autores: 
Zheng, W; Shu, XW; Moustakas, J; Zitrin, A; Ford, HC; Huang, XX; Broadhurst, T; Molino, A; Diego, JM; Infante, L; Bauer, FE; Kelson, DD; Smit, R
Resumen: 
We report the discovery of 24 Lyman-break candidates at 7 less than or similar to z less than or similar to 10.5, in the Hubble Frontier Fields (HFF) imaging data of A2744 (z = 0.308), plus Spitzer/IRAC data and archival ACS data. The sample includes a triple image system with a photometric redshift of z similar or equal to 7.4. This high redshift is geometrically confirmed by our lens model corresponding to deflection angles that are 12% larger than the lower-redshift systems used to calibrate the lens model at z = 2.019. The majority of our high-redshift candidates are not expected to be multiply lensed given their locations in the image plane and the brightness of foreground galaxies, but are magnified by factors of similar to 1.3-15, so that we are seeing further down the luminosity function than comparable deep-field imaging. It is apparent that the redshift distribution of these sources does not smoothly extend over the full redshift range accessible at z < 12, but appears to break above z = 9. Nine candidates are clustered within a small region of 20 '' across, representing a potentially unprecedented concentration. Given the poor statistics, however, we must await similar constraints from the additional HFF clusters to properly examine this trend. The physical properties of our candidates are examined using the range of lens models developed for the HFF program by various groups including our own, for a better estimate of underlying systematics. Our spectral-energy-distribution fits for the brightest objects suggest stellar masses of similar or equal to 10(9) M-circle dot, star formation rates of similar or equal to 4 M-circle dot yr(-1), and a typical formation redshift of z less than or similar to 19.
Autor principal: 
Zheng, W
Autor/es del IAA: 
Molino, Alberto
DOI: 
10.1088/0004-637X/795/1/93
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/11/01
Volumen: 
795
Issue: 
1
Tipo de documento: 
Article
Palabras clave: 
cosmology: observations; galaxies: clusters: individual (A2744); galaxies: high-redshift; gravitational lensing: strong
Número de artículo: 
93

Changes in the composition of the northern polar upper stratosphere in February 2009 after a sudden stratospheric warming

Titulo: 
Changes in the composition of the northern polar upper stratosphere in February 2009 after a sudden stratospheric warming
Autores: 
Damiani, A; Funke, B; Puertas, ML; Gardini, A; von Clarmann, T; Santee, ML; Froidevaux, L; Cordero, RR
Resumen: 
Variability in the chemistry of the upper stratosphere/lowermesosphere region has been analyzed focusing on high latitudes during the boreal winter in 2009 characterized by the strong sudden stratospheric warming (SSW) on 24 January. Data from Michelson Interferometer for Passive Atmospheric Sounding aboard Envisat and the Microwave Limb Sounder on Aura have been used to exemplify these changes. Record high (low) values of O-3 and ClO (temperature and HCl) for the winters of 2005-2012, coupled with a simultaneous enhancement of ClONO2, have been observed in February 2009. This suggests that the very low temperatures favor a more effective ozone production and a greater O-3/O ratio. The latter is the main factor controlling active chlorine partitioning. Increases of ClO lead to high ClONO2 concentrations in the upper stratosphere at high latitudes, where its photodissociation rate is smaller. Since this increase of ClONO2 happens at the expense of HCl, the region of high ClONO2 roughly coincides with the region of low HCl. Although this period was characterized by an elevated stratopause event, the investigated region was not influenced by the descent of mesospheric air rich in NOx. Some limited enhancements in NOx at similar to 1 hPa occurred at latitudes greater than 80 degrees N after about 20 February, but they became consistent only in March. Intrusion of midlatitude air mostly occurred between the SSW and early February. Then, the sum of volume mixing ratios of ClONO2 + ClO + HCl remained approximately constant and close to the values of the other years. In contrast, it was up to 0.2 ppbv lower during the SSW period. These atypical chemical conditions occurred also in February 2006, but 2009 stands out for its long-lasting effects, which persisted until late March.
Autor principal: 
Damiani, A
Autor/es del IAA: 
Funke, Bernd; Puertas, Manuel Lopez; Gardini, Angela
DOI: 
10.1002/2014JD021698
Revista: 
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
Fecha de publicación: 
2014/10/16
Volumen: 
119
Issue: 
19
Páginas: 
11429-11444
Tipo de documento: 
Article

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