Suchergebnisse

We study the rest-frame optical mass–size relation of bulges and discs from z ∼ 2 to z ∼ 0 for a complete sample of massive galaxies in the CANDELS fields using two-component Sérsic models. Discs and star-forming galaxies follow similar mass–size relations. The mass–size relation of bulges is less steep than the one of quiescent galaxies (best-fitting slope of 0.7 for quiescent galaxies against 0.4 for bulges). We find little dependence of the structural properties of massive bulges and discs with the global morphology of galaxies (disc versus bulge dominated) and the star formation activity (star-forming versus quiescent). This result suggests similar bulge formation mechanisms for most massive galaxies and also that the formation of the bulge component does not significantly affect the disc structure. Our results pose a challenge to current cosmological models that predict distinct structural properties for stellar bulges arising from mergers and disc instabilities. ; This work has been essentially funded by to a French national PhD scholarship. MHC is also thankful to Google for their unrestricted gift to explore deep-learning techniques for galaxy evolution. PGP-G acknowledges support from the Spanish Government grant AYA2015-63650-P. FS acknowledges partial support from a Leverhulme Trust Research Fellowship. ; Peer reviewed

We study the environmental dependence of color, stellar mass, and morphology by comparing galaxies in a forming cluster to those in the field at z = 1.6 with Hubble Space Telescope near-infrared imaging in the CANDELS/UDS field. We quantify the morphology of the galaxies using the effective radius, r(eff), and Sersic index, n. In both the cluster and field, approximately half of the bulge-dominated galaxies (n > 2) reside on the red sequence of the color-magnitude diagram, and most disk-dominated galaxies (n < 2) have colors expected for star-forming galaxies. There is weak evidence that cluster galaxies have redder rest-frame U - B colors and higher stellar masses compared to the field. Star-forming galaxies in both the cluster and field show no significant differences in their morphologies. In contrast, there is evidence that quiescent galaxies in the cluster have larger median effective radii and smaller Sersic indices compared to the field with a significance of 2 sigma. These differences are most pronounced for galaxies at clustercentric distances 1 Mpc < R-proj < 1.5 Mpc, which have low Sersic indices and possibly larger effective radii, more consistent with star-forming galaxies at this epoch and in contrast to other quiescent galaxies. We argue that star-forming galaxies are processed under the influence of the cluster environment at distances greater than the cluster-halo virial radius. Our results are consistent with models where gas accretion onto these galaxies is suppressed from processes associated with the cluster environment. ; NASA NAS5-26555 ; HST program GO-12060 ; NASA through a grant from the Space Telescope Science Institute GO-12060 ; NASA through Hubble Fellowship grant HF-51269.01-A ; Space Telescope Science Institute ; Southern California Center for Galaxy Evolution ; University of California Office of Research ; QEII Fellowship from theAustralian Government ; Astronomy

Following major successes in malaria control over the past 75 years, South Africa is now embarking on a malaria elimination campaign with the goal of zero local transmission by the year 2018. The key control elements have been intensive vector control, primarily through indoor residual spraying, case management based on parasitological diagnosis using evidence-based drug policies with artemisinin-based combination therapy since 2001, active health promotion in partnership with communities living in the malaria transmission areas, and cross-border collaborations. Political commitment and long-term funding for the malaria control programme have been a critical component of the programme's success. Breaking the cycle of transmission through strengthening of active surveillance using sensitive molecular tests and field treatment of asymptomatic persons, monitoring for antimalarial drug resistance and insecticide resistance, strengthening cross-border initiatives, and ongoing programme advocacy in the face of a significant decrease in disease burden are key priorities for achieving the elimination goal. ; http://www.samj.org.za ; am2015

Dust-enshrouded, starbursting, submillimeter galaxies (SMGs) at z ≥ 3 have been proposed as progenitors of z ≥ 2 compact quiescent galaxies (cQGs). To test this connection, we present a detailed spatially resolved study of the stars, dust, and stellar mass in a sample of six submillimeter-bright starburst galaxies at z ∼ 4.5. The stellar UV emission probed by HST is extended and irregular and shows evidence of multiple components. Informed by HST, we deblend Spitzer/IRAC data at rest-frame optical, finding that the systems are undergoing minor mergers with a typical stellar mass ratio of 1:6.5. The FIR dust continuum emission traced by ALMA locates the bulk of star formation in extremely compact regions (median r = 0.70 ± 0.29 kpc), and it is in all cases associated with the most massive component of the mergers (median ). We compare spatially resolved UV slope (β) maps with the FIR dust continuum to study the infrared excess (IRX = L /L )-β relation. The SMGs display systematically higher IRX values than expected from the nominal trend, demonstrating that the FIR and UV emissions are spatially disconnected. Finally, we show that the SMGs fall on the mass-size plane at smaller stellar masses and sizes than the cQGs at z = 2. Taking into account the expected evolution in stellar mass and size between z = 4.5 and z = 2 due to the ongoing starburst and mergers with minor companions, this is in agreement with a direct evolutionary connection between the two populations. © 2018. The American Astronomical Society. All rights reserved. ; C.G.G. and S.T. acknowledge support from the European Research Council (ERC) Consolidator Grant funding scheme (project ConTExt, grant number 648179). A.K., E.J.A., and F.B. acknowledge support by the Collaborative Research Centre 956, subproject A1, funded by the Deutsche Forschungsgemeinschaft (DFG). Support for B.M. was provided by the DFG priority program 1573, "The physics of the interstellar medium." D.R. acknowledges support from the National Science Foundation under grant number AST-1614213. V.S. acknowledges support from the European Union's Seventh Framework program under grant agreement 337595 (ERC Starting Grant, "CoSMass"). M.A. acknowledges partial support from FONDECYT through grant 1140099. ERD also acknowledge support by the Collaborative Research Centre 956, subproject C4, funded by the DFG. M.J.M. acknowledges the support of the National Science Centre, Poland, through POLONEZ grant 2015/19/P/ST9/04010; this project has received funding from the European Union's Horizon 2020 research and innovation program under Marie Sklodowska-Curie grant agreement No. 665778. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #13294. Support for program #13294 was provided by NASA through a grant from the Space Telescope Science Institute.

The Astrophysical Journal 806.1 (2015): 4 reproduced by permission of the AAS ; We present a new determination of the concentration-mass (c-M) relation for galaxy clusters based on our comprehensive lensing analysis of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble (CLASH). Our sample spans a redshift range between 0.19 and 0.89. We combine weak-lensing constraints from the Hubble Space Telescope (HST) and from ground-based wide-field data with strong lensing constraints from HST. The results are reconstructions of the surface-mass density for all CLASH clusters on multi-scale grids. Our derivation of Navarro-Frenk-White parameters yields virial masses between 0.53 x 10 15 M⊙/ h and 1.76 x 10 15 M⊙/ h and the halo concentrations are distributed around c200c∼3.7 with a 1σ significant negative slope with cluster mass. We find an excellent 4% agreement in the median ratio of our measured concentrations for each cluster and the respective expectation from numerical simulations after accounting for the CLASH selection function based on X-ray morphology. The simulations are analyzed in two dimensions to account for possible biases in the lensing reconstructions due to projection effects. The theoretical c-M relation from our X-ray selected set of simulated clusters and the c-M relation derived directly from the CLASH data agree at the 90% confidence level ; The research was in part carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. J. M. has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007–2013) under REA grant agreement number 627288. M. M. thanks ORAU and NASA for supporting his research at JPL and acknowledges support from the contract ASI/INAF I/023/12/0, INFN/PD51, and the PRIN MIUR 20102011 "The dark universe and the cosmic evolution of baryons: from current surveys to Euclid." K. U. acknowledges support from the National Science Council of Taiwan (grant NSC100-2112-M-001-008-MY3) and from the Academia Sinica Career Development Award. Support for A. Z. is provided by NASA through Hubble Fellowship grant #HST-HF-51334.01 A awarded by STScI. D. G., S. S. and P. R. were supported by SFB Transregio 33 "The Dark universe" by the Deutsche Forschungsgemeinschaft (DFG) and the DFG cluster of excellence "Origin and Structure of the universe." This work was supported in part by contract research "Internationale Spitzenforschung II/2-6" of the Baden Württemberg Stiftung. The Dark Cosmology Centre is funded by the DNRF. J. S. was supported by NSF/AST1313447, NASA/NNX11AB07G, and the Norris Foundation CCAT Postdoctoral Fellowship. E.R. acknowledges support from the National Science Foundation AST-1210973, SAO TM3-14008X (issued under NASA Contract No. NAS8-03060)

We present accurate photometric redshifts for galaxies observed by the Cluster Lensing And Supernova survey with Hubble (CLASH). CLASH observed 25 massive galaxy cluster cores with the Hubble Space Telescope in 16 filters spanning 0.2-1.7 μm. Photometry in such crowded fields is challenging. Compared to our previously released catalogues, we make several improvements to the photometry, including smaller apertures, intracluster light subtraction, point spread function matching and empirically measured uncertainties. We further improve the Bayesian photometric redshift estimates by adding a redder elliptical template and by inflating the photometric uncertainties of the brightest galaxies. The resulting photometric redshift accuracies are dz/(1+z) ~ 0.8, 1.0 and 2.0 per cent for galaxies with I-band F814W AB magnitudes < 18, 20 and 23, respectively. These results are consistent with our expectations. They improve on our previously reported accuracies by a factor of 4 at the bright end and a factor of 2 at the faint end. Our new catalogue includes 1257 spectroscopic redshifts, including 382 confirmed cluster members. We also provide stellar mass estimates. Finally, we include lensing magnification estimates of background galaxies based on our public lens models. Our new catalogue of all 25 CLASH clusters is available via Mikulski Archive for Space Telescopes. The analysis techniques developed here will be useful in other surveys of crowded fields, including the Frontier Fields and surveys carried out with Javalambre-Physics of the Accelerated Universe Astrophysical Survey and James Webb Space Telescope.© 2017 The Authors. ; We acknowledge the financial support of the Brazilian funding agency FAPESP (Post-doc fellowship - process number 2014/11806-9). Likewise, we also acknowledge the Spanish Ministerio de Educacion y Ciencia through grant AYA2006-14056 BES-2007-16280. We acknowledge the financial support from the Spanish MICINN under the Consolider-Ingenio 2010 Program grant CSD2006-00070: First Science with the GTC. AM acknowledges the CEFCA (Centro de Estudios de Fisica del Cosmos de Aragon) and the IAA-CSIC (Instituto de Astrofisica de Andalucia) institutes for hosting him during the period 2015/2016. PR, MM, AMe and MN acknowledge the financial support from PRIN-INAF 2014 1.05.01.94.02. Likewise, AMacknowledges the STScI (Space Telescope Science Institute) for hosting him during 2010 AugustSeptember, 2011 June-August and 2016 July. We acknowledge the financial support of ESO since most of the spectroscopic redshifts used in the work were based on ESO VLT programme ID 186.A-0798. BA has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 656354. ; Peer Reviewed

Galaxies with stellar masses near M* contain the majority of stellar mass in the universe, and are therefore of special interest in the study of galaxy evolution. The Milky Way (MW) and Andromeda (M31) have present-day stellar masses near M*, at 5 x 10(10) M-circle dot (defined here to be MW-mass) and 10(11) M-circle dot (defined to be M31-mass). We study the typical progenitors of these galaxies using the FOURSTAR Galaxy Evolution Survey (ZFOURGE). ZFOURGE is a deep medium-band near-IR imaging survey, which is sensitive to the progenitors of these galaxies out to z similar to 3. We use abundance-matching techniques to identify the main progenitors of these galaxies at higher redshifts. We measure the evolution in the stellar mass, rest-frame colors, morphologies, far-IR luminosities, and star formation rates, combining our deep multiwavelength imaging with near-IR Hubble Space Telescope imaging from Cosmic Near-IR Deep Extragalactic Legacy Survey (CANDELS), and Spitzer and Herschel far-IR imaging from Great Observatories Origins Deep Survey-Herschel and CANDELS-Herschel. The typical MW-mass and M31-mass progenitors passed through the same evolution stages, evolving from blue, star-forming disk galaxies at the earliest stages to redder dust-obscured IR-luminous galaxies in intermediate stages and to red, more quiescent galaxies at their latest stages. The progenitors of the MW-mass galaxies reached each evolutionary stage at later times (lower redshifts) and with stellar masses that are a factor of two to three lower than the progenitors of the M31-mass galaxies. The process driving this evolution, including the suppression of star formation in present-day M* galaxies, requires an evolving stellar-mass/halo-mass ratio and/or evolving halo-mass threshold for quiescent galaxies. The effective size and SFRs imply that the baryonic cold-gas fractions drop as galaxies evolve from high redshift to z similar to 0 and are strongly anticorrelated with an increase in the Sersic index. Therefore, the growth of galaxy bulges in M* galaxies corresponds to a rapid decline in the galaxy gas fractions and/or a decrease in the star formation efficiency. ; National Science Foundation AST-1009707, AST-0808133 ; ERC HIGHZ 227749 ; NL-NWO Spinoza ; NASA NAS5-26555 ; HST program GO-12060 ; National Collaborative Research Infrastructure Strategy of the Australian Federal Government ; Texas A&M University ; George P. and Cynthia Woods Institute for Fundamental Physics and Astronomy ; Astronomy