1,115 research outputs found

    A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA

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    The authors thank the Viabilidad, Diseño, Acceso y Mejorafunding program, ICTS-2009-10, for supporting the initial development of this project. S.F.S., F.F.R.O. and D. Mast thank the Plan Nacional de Investigación y Desarrollo funding programs, AYA2010-22111-C03-03 and AYA2010-10904E, of the Spanish Ministerio de Ciencia e Innovación, for their support for this project. S.F.S thanks the Ramón y Cajal project RyC-2011-07590 of the Spanish Ministerio de Economía y Competitividad, for their support for this project. S.F.S. and B.J. acknowledge support from the grants No. M100031241 and M100031201 of the Academy of Sciences of the Czech Republic (ASCR Internal support program of international cooperation projects – PIPPMS) and by the Czech Republic program for the long-term development of the research institution No. RVO67985815. R.G.D., E.P., and R.G.B. thank the Plan Nacional de Investigación y Desarrollo funding program AYA2010-15081. F.F.R.O. acknowledges the Mexican National Council for Science and Technology (CONACYT) for financial support under the program Estancias Posdoctorales y Sabáticas al Extranjero para la Consolidación de Grupos de Investigación, 2010-2012. I.M. and J.P. acknowledge financial support from the Spanish grant AYA2010-15169 and Junta de Andalucía TIC114 and Excellence Project P08-TIC-03531. D.M. and A.M.-I. are supported by the Spanish Research Council within the program JAE-Doc, Junta para la Ampliación de Estudios, cofunded by the FSE. R.A. Marino was also funded by the Spanish program of the International Campus of Excellence Moncloa (CEI). J.I.-P., J.M.V., A.M.-I., and C.K. have been partially funded by the projects AYA2010-21887 from the Spanish PNAYA, CSD2006 – 00070 “1st Science with GTC” from the CONSOLIDER 2010 program of the Spanish MICINN, and TIC114 Galaxias y Cosmología of the Junta de Andalucía (Spain). M.A.P.T. acknowledges support by the Spanish MICINN through grant AYA2012-38491-C02-02 and by the Autonomic Government of Andalusia through grants P08-TIC-4075 and TIC-126. CJW acknowledges support through the Marie Curie Career Integration Grant 303912. Polychronis Papaderos is supported by a Ciencia 2008 contract, funded by FCT/MCTES (Portugal) and POPH/FSE (EC). Jean Michel Gomes is supported by a grant SFRH/BPD/66958/2009 from FCT (Portugal).We present the largest and most homogeneous catalog of H II regions and associations compiled so far. The catalog comprises more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey. We describe the procedures used to detect, select, and analyze the spectroscopic properties of these ionized regions. In the current study we focus on characterizing of the radial gradient of the oxygen abundance in the ionized gas, based on the study of the deprojected distribution of H II regions. We found that all galaxies without clear evidence of an interaction present a common gradient in the oxygen abundance, with a characteristic slope of aO/H = -0.1 dex/re between 0.3 and 2 disk effective radii (re), and a scatter compatible with random fluctuations around this value, when the gradient is normalized to the disk effective radius. The slope is independent of morphology, the incidence of bars, absolute magnitude, or mass. Only those galaxies with evidence of interactions and/or clear merging systems present a significantly shallower gradient, consistent with previous results. The majority of the 94 galaxies with H II regions detected beyond two disk effective radii present a flattening in the oxygen abundance. The flattening is statistically significant. We cannot provide a conclusive answer regarding the origin of this flattening. However, our results indicate that its origin is most probably related to the secular evolution of galaxies. Finally, we find a drop/truncation of the oxygen abundance in the inner regions for 26 of the galaxies. All of them are non-interacting, mostly unbarred Sb/Sbc galaxies. This feature is associated with a central star-forming ring, which suggests that both features are produced by radial gas flows induced by resonance processes. Our result suggests that galaxy disks grow inside-out, with metal enrichment driven by the local star formation history and with a small variation galaxy-by-galaxy. At a certain galactocentric distance, the oxygen abundance seems to be correlated well with the stellar mass density and total stellar mass of the galaxies, independently of other properties of the galaxies. Other processes, such as radial mixing and inflows/outflows seem to have a limited effect on shaping of the radial distribution of oxygen abundances, although they are not ruled out.Peer reviewe

    Stellar populations across galaxy bars in the MUSE TIMER project

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    Stellar populations in barred galaxies save an imprint of the influence of the bar on the host galaxy’s evolution. We present a detailed analysis of star formation histories (SFHs) and chemical enrichment of stellar populations in nine nearby barred galaxies from the TIMER project. We used integral field observations with the MUSE instrument to derive unprecedented spatially resolved maps of stellar ages, metallicities, [Mg/Fe] abundances, and SFHs, as well as Hα as a tracer of ongoing star formation. We find a characteristic V-shaped signature in the SFH that is perpendicular to the bar major axis, which supports the scenario where intermediate-age stars (∼2 − 6 Gyr) are trapped on more elongated orbits shaping a thinner part of the bar, while older stars (> 8 Gyr) are trapped on less elongated orbits shaping a rounder and thicker part of the bar. We compare our data to state-of-the-art cosmological magneto-hydrodynamical simulations of barred galaxies and show that such V-shaped SFHs arise naturally due to the dynamical influence of the bar on stellar populations with different ages and kinematic properties. Additionally, we find an excess of very young stars (< 2 Gyr) on the edges of the bars, predominantly on the leading side, thus confirming typical star formation patterns in bars. Furthermore, mass-weighted age and metallicity gradients are slightly shallower along the bar than in the disc, which is likely due to orbital mixing in the bar. Finally, we find that bars are mostly more metal-rich and less [Mg/Fe]-enhanced than the surrounding discs. We interpret this as a signature that the bar quenches star formation in the inner region of discs, usually referred to as star formation deserts. We discuss these results and their implications on two different scenarios of bar formation and evolution

    Outer-disk reddening and gas-phase metallicities: The CALIFA connection

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    Astronomy and Astrophysics 585 (2016): A47 reproduced with permission from Astronomy & AstrophysicsWe study, for the first time in a statistically significant and well-defined sample, the relation between the outer-disk ionized-gas metallicity gradients and the presence of breaks in the surface brightness profiles of disk galaxies. Sloan Digital Sky Survey (SDSS) g′- and r′-band surface brightness, (g′ - r′) color, and ionized-gas oxygen abundance profiles for 324 galaxies within the Calar Alto Legacy Integral Field Area (CALIFA) survey are used for this purpose. We perform a detailed light-profile classification, finding that 84% of our disks show down- or up-bending profiles (Type II and Type III, respectively), while the remaining 16% are well fitted by one single exponential (Type I). The analysis of the color gradients at both sides of this break shows a U-shaped profile for most Type II galaxies with an average minimum (g′ - r′) color of ∼ 0.5mag and an ionized-gas metallicity flattening associated with it only in the case of low-mass galaxies. Comparatively, more massive systems show a rather uniform negative metallicity gradient. The correlation between metallicity flattening and stellar mass for these systems results in p-values as low as 0.01. Independent of the mechanism having shaped the outer light profiles of these galaxies, stellar migration or a previous episode of star formation in a shrinking star-forming disk, it is clear that the imprint in their ionized-gas metallicity was different for low- and high-mass Type II galaxies. In the case of Type III disks, a positive correlation between the change in color and abundance gradient is found (the null hypothesis is ruled out with a p-value of 0.02), with the outer disks of Type III galaxies with masses ≤1010 M′ showing a weak color reddening or even a bluing. This is interpreted as primarily due to a mass downsizing effect on the population of Type III galaxies that recently experienced an enhanced inside-out growthWe acknowledge support from the Plan Nacional de Investigación y Desarrollo funding programs, AyA2010-15081, AyA2012-30717 and AyA2013-46724P, of Spanish Ministerio de Economía y Competitividad (MINECO). A.G.d.P. acknowledges the support from the FP7 Marie Curie Actions of the European Commission, via the Initial Training Network DAGAL under REA grant agreement PITNGA- 2011-289313. C.C.-T. thanks the support of the Spanish Ministerio de Educación, Cultura y Deporte by means of the FPU fellowship program. C.J.W. acknowledges support through the Marie Curie Career Integration Grant 303912. Support for L.G. is provided by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC 120009, awarded to The Millennium Institute of Astrophysics, MAS. L.G. acknowledges support by CONIC YT through FONDECYT grant 3140566. S.F.S. thanks the CONACYT-125180 and DGAPA-IA100815 projects for providing him support in this study. J.M.A. acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild). P.P. is supported by FCT through the Investigador FCT Contract No. IF/01220/2013 and POPH/FSE (EC) by FEDER funding through the program COMPETE. He also acknowledges support by FCT under project FCOMP-01-0124-FEDER-029170 (Reference FCT PTDC/FISAST/ 3214/2012), funded by FCT-MEC (PIDDAC) and FEDER (COMPETE

    Shape of the oxygen abundance profiles in CALIFA face-on spiral galaxies

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    Astronomy & Astrophysics 587 (2016): A70 reproduced with permission from Astronomy & AstrophysicsWe measured the gas abundance profiles in a sample of 122 face-on spiral galaxies observed by the CALIFA survey and included all spaxels whose line emission was consistent with star formation. This type of analysis allowed us to improve the statistics with respect to previous studies, and to properly estimate the oxygen distribution across the entire disc to a distance of up to 3-4 disc effective radii (re). We confirm the results obtained from classical H ii region analysis. In addition to the general negative gradient, an outer flattening can be observed in the oxygen abundance radial profile. An inner drop is also found in some cases. There is a common abundance gradient between 0.5 and 2.0 re of αO/H =-0.075 dex/re with a scatter of σ = 0.016 dex/re when normalising the distances to the disc effective radius. By performing a set of Kolmogorov-Smirnov tests, we determined that this slope is independent of other galaxy properties, such as morphology, absolute magnitude, and the presence or absence of bars. In particular, barred galaxies do not seem to display shallower gradients, as predicted by numerical simulations. Interestingly, we find that most of thegalaxies in the sample with reliable oxygen abundance values beyond ~2 effective radii (57 galaxies) present a flattening of the abundance gradient in these outer regions. This flattening is not associated with any morphological feature, which suggests that it is a common property of disc galaxies. Finally, we detect a drop or truncation of the abundance in the inner regions of 27 galaxies in the sample; this is only visible for the most massive galaxiesWe acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) via grant AYA2012-31935, and from the “Junta de Andalucía” local government through the FQM-108 project. We also acknowledge support to the ConaCyt funding program 180125. Y.A. acknowledges fi- nantial support from the Ramón y Cajal programme (RyC-2011-09461). Y.A. and A.I.D. acknowledge support from the project AYA2013-47742-C4-3-P from the Spanish MINECO, as well as the “Study of Emission-Line Galaxies with Integral-Field Spectroscopy” (SELGIFS) programme, funded by the EU (FP7- PEOPLE-2013-IRSES-612701). Support for L.G. is provided by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. LG acknowledges support by CONICYT through FONDECYT grant 3140566. R.M.G.D. acknowledges support from the Spanish grant AYA2014-57490-P, and from the “Junta de Andalucía” P12-FQM2828 project. RAM thanks the Spanish program of International Campus of Excellence Moncloa (CEI). IM and A.d.O. acknowledge support from the Spanish MINECO grant AYA2013-42227P. JMA acknowledges support from the European Research Council Starting Grant (SEDmorph, P.I. V. Wild). Support for MM has been provided by DGICYT grant AYA2013-47742-C4-4-P. PSB acknowledges support from the Ramón y Cajal programme, grant ATA2010-21322-C03-02 from the Spanish MINECO. CJW acknowledges support through the Marie Curie Career Grant Integration 30391

    Leptonic and Semileptonic Decays of Charm and Bottom Hadrons

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    We review the experimental measurements and theoretical descriptions of leptonic and semileptonic decays of particles containing a single heavy quark, either charm or bottom. Measurements of bottom semileptonic decays are used to determine the magnitudes of two fundamental parameters of the standard model, the Cabibbo-Kobayashi-Maskawa matrix elements VcbV_{cb} and VubV_{ub}. These parameters are connected with the physics of quark flavor and mass, and they have important implications for the breakdown of CP symmetry. To extract precise values of Vcb|V_{cb}| and Vub|V_{ub}| from measurements, however, requires a good understanding of the decay dynamics. Measurements of both charm and bottom decay distributions provide information on the interactions governing these processes. The underlying weak transition in each case is relatively simple, but the strong interactions that bind the quarks into hadrons introduce complications. We also discuss new theoretical approaches, especially heavy-quark effective theory and lattice QCD, which are providing insights and predictions now being tested by experiment. An international effort at many laboratories will rapidly advance knowledge of this physics during the next decade.Comment: This review article will be published in Reviews of Modern Physics in the fall, 1995. This file contains only the abstract and the table of contents. The full 168-page document including 47 figures is available at http://charm.physics.ucsb.edu/papers/slrevtex.p

    CariesCare International adapted for the pandemic in children: Caries OUT multicentre single-group interventional study protocol

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    Fil: Martignon, Stefania. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Douglas, Gail V. A. University of Leeds. Dental Public Health. Dental Institute; United Kingdom.Fil: Cortes, Andrea. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Newton, J. Timothy. King’s College. Faculty of Dentistry. Oral and Craniofacial Sciences; United Kingdom.Fil: Pitts, Nigel B. King’s College. Faculty of Dentistry. Oral and Craniofacial Sciences; United Kingdom.Fil: Ávila, Viviana. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Usuga Vacca, Margarita. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Usuga Vacca, Margarita. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Gamboa, Luis F. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Deery, Christopher. University of Sheffield. School of Clinical Dentistry; United Kingdom.Fil: Abreu - Placeres, Ninoska. Universidad Iberoamericana. Biomaterials and Dentistry Research Center. Academic Research Department; República Dominicana.Fil: Bonifacio, Clarisa. Academic Center for Dentistry Amsterdam. Department of Pediatric Dentistry; Países Bajos.Background: Comprehensive caries care has shown effectiveness in controlling caries progression and improving health outcomes by controlling caries risk, preventing initial-caries lesions progression, and patient satisfaction. To date, the caries-progression control effectiveness of the patient-centred risk-based cariesCare International (CCI) system, derived from ICCMS™ for the practice (2019), remains unproven. With the onset of the COVID-19 pandemic a previously planned multi-centre RCT shifted to this “Caries OUT” study, aiming to assess in a single-intervention group in children, the caries-control effectiveness of CCI adapted for the pandemic with non-aerosols generating procedures (non-AGP) and reducing in-office time. Methods: In this 1-year multi-centre single-group interventional trial the adapted-CCI effectiveness will be assessed in one single group in terms of tooth-surface level caries progression control, and secondarily, individual-level caries progression control, children’s oral-health behaviour change, parents’ and dentists’ process acceptability, and costs exploration. A sample size of 258 3–5 and 6–8 years old patients was calculated after removing half from the previous RCT, allowing for a 25% dropout, including generally health children (27 per centre). The single-group intervention will be the adapted-CCI 4D-cycle caries care, with non-AGP and reduced in-office appointments’ time. A trained examiner per centre will conduct examinations at baseline, at 5–5.5 months (3 months after basic management), 8.5 and 12 months, assessing the child’s CCI caries risk and oral-health behaviour, visually staging and assessing carieslesions severity and activity without air-drying (ICDAS-merged Epi); fillings/sealants; missing/dental-sepsis teeth, and tooth symptoms, synthetizing together with parent and external-trained dental practitioner (DP) the patient- and tooth-surface level diagnoses and personalised care plan. DP will deliver the adapted-CCI caries care. Parents’ and dentists’ process acceptability will be assessed via Treatment-Evaluation-Inventory questionnaires, and costs in terms of number of appointments and activities. Twenty-one centres in 13 countries will participate. Discussion: The results of Caries OUT adapted for the pandemic will provide clinical data that could help support shifting the caries care in children towards individualised oral-health behaviour improvement and tooth-preserving care, improving health outcomes, and explore if the caries progression can be controlled during the pandemic by conducting non-AGP and reducing in-office time.publishedVersionFil: Martignon, Stefania. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Douglas, Gail V. A. University of Leeds. Dental Public Health. Dental Institute; United Kingdom.Fil: Cortes, Andrea. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Newton, J. Timothy. King’s College. Faculty of Dentistry. Oral and Craniofacial Sciences; United Kingdom.Fil: Pitts, Nigel B. King’s College. Faculty of Dentistry. Oral and Craniofacial Sciences; United Kingdom.Fil: Ávila, Viviana. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Usuga Vacca, Margarita. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Usuga Vacca, Margarita. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Gamboa, Luis F. Universidad El Bosque. Caries Research Unit. Research Department; Colombia.Fil: Deery, Christopher. University of Sheffield. School of Clinical Dentistry; United Kingdom.Fil: Abreu - Placeres, Ninoska. Universidad Iberoamericana. Biomaterials and Dentistry Research Center. Academic Research Department; República Dominicana.Fil: Bonifacio, Clarisa. Academic Center for Dentistry Amsterdam. Department of Pediatric Dentistry; Países Bajos.Otras Ciencias de la Salu

    Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

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    A measurement of the cosmic-ray spectrum for energies exceeding 4×10184{\times}10^{18} eV is presented, which is based on the analysis of showers with zenith angles greater than 6060^{\circ} detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above 5.3×10185.3{\times}10^{18} eV, the "ankle", the flux can be described by a power law EγE^{-\gamma} with index γ=2.70±0.02(stat)±0.1(sys)\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)} followed by a smooth suppression region. For the energy (EsE_\text{s}) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25(stat)1.2+1.0(sys))×1019E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19} eV.Comment: Replaced with published version. Added journal reference and DO

    Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

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    The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
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