Suchergebnisse

Context. Knowing the exact shape of the ultraviolet (UV) luminosity function (LF) of high-redshift galaxies is important to understand the star formation history of the early Universe. However, the uncertainties, especially at the faint and bright ends of the LFs, remain significant. Aims. In this paper, we study the UV LF of redshift z = 2:5 4.5 galaxies in 2.38 deg of ALHAMBRA data with I ≤ 24. Thanks to the large area covered by ALHAMBRA, we particularly constrain the bright end of the LF. We also calculate the cosmic variance and the corresponding bias values for our sample and derive their host dark matter halo masses. Methods.We have used a novel methodology based on redshift and magnitude probability distribution functions (PDFs). This methodology robustly takes into account the uncertainties due to redshift and magnitude errors, shot noise, and cosmic variance, and models the LF in two dimensions (z; M). Results. We find an excess of bright ∼M∗ galaxies as compared to the studies based on broad-band photometric data. However, our results agree well with the LF of the magnitude-selected spectroscopic VVDS data. We measure high bias values, b ∼ 8 10, that are compatible with the previous measurements considering the redshifts and magnitudes of our galaxies and further reinforce the real high-redshift nature of our bright galaxies. Conclusions. We call into question the shape of the LF at its bright end; is it a double power-law as suggested by the recent broadband photometric studies or rather a brighter Schechter function, as suggested by our multi-filter analysis and the spectroscopic VVDS data.© ESO 2018. ; K. Viironen acknowledges the >Juan de la Cierva incorporacion> fellowship, IJCI-2014-21960, of the Spanish government. This work has mainly been funded by the FITE (Fondos de Inversiones de Teruel) and the projects AYA2015-66211-C2-1 and AYA2012-30789. We also acknowledge support from the Aragon Government Research Group E103 and support from the Spanish Ministry for Economy and Competitiveness and FEDER funds through grants AYA2010-15081, AYA2010-15169, AYA2010-22111-C03-01, AYA2010-22111-C03-02, AYA2011-29517-C03-01, AYA2012-39620, AYA2013-40611-P, AYA2013-42227-P, AYA2013-43188-P, AYA2013-48623-C2-1, AYA2013-48623-C2-2, ESP2013-48274, AYA2014-58861-C3-1, AYA2016-76682-C3-1-P, Generalitat Valenciana projects Prometeo 2009/064 and PROMETEOII/2014/060, Junta de Andalucia grants TIC114, JA2828, P10-FQM-6444, and Generalitat de Catalunya project SGR-1398. BA has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 656354. MP acknowledges financial supports from the Ethiopian Space Science and Technology Institute (ESSTI) under the Ethiopian Ministry of Science Science and Technology (MoST) ; Peer Reviewed

Reproduced with permission from Astronomy & Astrophysics ; We present a technique that permits the analysis of stellar population gradients in a relatively low-cost way compared to integral field unit (IFU) surveys. We developed a technique to analyze unresolved stellar populations of spatially resolved galaxies based on photometric multi-filter surveys. This technique allows the analysis of vastly larger samples and out to larger galactic radii. We derived spatially resolved stellar population properties and radial gradients by applying a centroidal Voronoi tessellation and performing a multicolor photometry spectral energy distribution fitting. This technique has been successfully applied to a sample of 29 massive (M ∗ > 10 10.5 M ⊙ ) early-type galaxies at z < 0.3 from the ALHAMBRA survey. We produced detailed 2D maps of stellar population properties (age, metallicity, and extinction), which allow us to identify galactic features. Radial structures were studied, and luminosity-weighted and mass-weighted gradients were derived out to 2-3.5 R eff . We find that the spatially resolved stellar population mass, age, and metallicity are well represented by their integrated values. We find the gradients of early-type galaxies to be on average flat in age (⇠log Age L = 0.02 ± 0.06 dex/R eff ) and negative in metallicity (⇠[Fe/H] L = -0.09 ± 0.06 dex/R eff ). Overall,the extinction gradients are flat (⇠A v = -0.03 ± 0.09 mag/R eff ) with a wide spread. These results are in agreement with previous studies that used standard long-slit spectroscopy, and with the most recent IFU studies. According to recent simulations, these results are consistent with a scenario where early-type galaxies were formed through major mergers and where their final gradients are driven by the older ages and higher metallicity of the accreted systems. We demonstrate the scientific potential of multi-filter photometry to explore the spatially resolved stellar populations of local galaxies and confirm previous spectroscopic trends from a complementary technique ; This work has been mainly funded by the FITE (Fondos de Inversiones de Teruel) and the Spanish Ministry for Economy and Competitiveness and FEDER funds through grants AYA2012-30789 and AYA2015-66211-C2-1-P. We also acknowledge financial support from the projects AYA2014-57490-P and AYA2016-77846-P, and from the Aragón Government through the Research Group E103. B.A. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 656354. M.P. acknowledges financial supports from the Ethiopian Space Science and Technology Institute (ESSTI) under the Ethiopian Ministry of Science and Technology (MoST), and from the Spanish Ministry of Economy and Competitiveness (MINECO) through research projects AYA2013-42227-P and AYA2016-76682-C3-1-P (AEI/FEDER, UE).

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