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756 results on '"Charlot, Stéphane"'

404. Pathways to quiescence: SHARDS view on the star formation histories of massive quiescent galaxies at 1.0 < 1.5

Author

Domínguez Sánchez, Helena, primary, Pérez-González, Pablo G., additional, Esquej, Pilar, additional, Eliche-Moral, M. Carmen, additional, Barro, Guillermo, additional, Cava, Antonio, additional, Koekemoer, Anton M., additional, Alcalde Pampliega, Belén, additional, Alonso Herrero, Almudena, additional, Bruzual, Gustavo, additional, Cardiel, Nicolás, additional, Cenarro, Javier, additional, Ceverino, Daniel, additional, Charlot, Stéphane, additional, and Hernán Caballero, Antonio, additional

Published
2016
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405. Strong Gravitational Lensing and the Stellar IMF of Early-type Galaxies

Author

Leier, Dominik, Ferreras, Ignacio, Saha, Prasenjit, Charlot, Stéphane, Bruzual, Gustavo, La Barbera, Francesco, Leier, Dominik, Ferreras, Ignacio, Saha, Prasenjit, Charlot, Stéphane, Bruzual, Gustavo, and La Barbera, Francesco

Abstract

Systematic variations of the IMF in early-type galaxies, and their connection with possible drivers such as velocity dispersion or metallicity, have been much debated in recent years. Strong lensing over galaxy scales combined with photometric and spectroscopic data provides a powerful method to constrain the stellar mass-to-light ratio and hence the functional form of the IMF. We combine photometric and spectroscopic constraints from the latest set of population synthesis models of Charlot & Bruzual, including a varying IMF, with a non-parametric analysis of the lens masses of 18 ETGs from the SLACS survey, with velocity dispersions in the range 200-300 km/s. We find that very bottom-heavy IMFs are excluded. However, the upper limit to the bimodal IMF slope ($\mu \lesssim 2.2$, accounting for a dark matter fraction of 20-30%, where $\mu=1.3$ corresponds to a Kroupa-like IMF) is compatible at the $1\sigma$ level with constraints imposed by gravity-sensitive line strengths. A two-segment power law parameterisation of the IMF (Salpeter-like for high masses) is more constrained ($\Gamma \lesssim 1.5$, where $\Gamma$ is the power index at low masses) but requires a dark matter contribution of $\gtrsim 25\%$ to reconcile the results with a Salpeter IMF. For a standard Milky Way-like IMF to be applicable, a significant dark matter contribution is required within $1R_e$. Our results reveal a large range of allowed IMF slopes, which, when interpreted as intrinsic scatter in the IMF properties of ETGs, could explain the recent results of Smith et al., who find Milky Way-like IMF normalisations in a few massive lensing ETGs., Comment: Accepted for publication in MNRAS, 18 pages, 12 figures, 4 tables

Published
2015
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406. Pathways to quiescence: SHARDS view on the Star Formation Histories of massive quiescent galaxies at 1.0 < z < 1.5

Author

Sánchez, Helena Domínguez, Pérez-González, Pablo G., Esquej, Pilar, Eliche-Moral, M. Carmen, Barro, Guillermo, Cava, Antonio, Koekemoer, Anton M., Pampliega, Belén Alcalde, Herrero, Almudena Alonso, Bruzual, Gustavo, Cardiel, Nicolás, Cenarro, Javier, Ceverino, Daniel, Charlot, Stéphane, Caballero, Antonio Hernán, Sánchez, Helena Domínguez, Pérez-González, Pablo G., Esquej, Pilar, Eliche-Moral, M. Carmen, Barro, Guillermo, Cava, Antonio, Koekemoer, Anton M., Pampliega, Belén Alcalde, Herrero, Almudena Alonso, Bruzual, Gustavo, Cardiel, Nicolás, Cenarro, Javier, Ceverino, Daniel, Charlot, Stéphane, and Caballero, Antonio Hernán

Abstract

We present Star Formation Histories (SFHs) for a sample of 104 massive (stellar mass M > 10$^{10}$ M$_{\odot}$) quiescent galaxies (MQGs) at $z$=1.0-1.5 from the analysis of spectro-photometric data from the SHARDS and HST/WFC3 G102 and G141 surveys of the GOODS-N field, jointly with broad-band observations from ultraviolet (UV) to far-infrared (Far-IR). The sample is constructed on the basis of rest-frame UVJ colours and specific star formation rates (sSFR=SFR/Mass). The Spectral Energy Distributions (SEDs) of each galaxy are compared to models assuming a delayed exponentially declining SFH. A Monte Carlo algorithm characterizes the degeneracies, which we are able to break taking advantage of the SHARDS data resolution, by measuring indices such as MgUV and D4000. The population of MQGs shows a duality in their properties. The sample is dominated (85%) by galaxies with young mass-weighted ages, tM $<$ 2 Gyr, short star formation timescales, $\langle \tau \rangle$ $\sim$ 60-200 Myr, and masses log(M/M$_{\odot}$) $\sim$ 10.5. There is an older population (15%) with tM$=$2 - 4 Gyr, longer star formation timescales, $\langle \tau \rangle$$\sim$ 400 Myr, and larger masses, log(M/M$_{\odot}$) $\sim$ 10.7. The SFHs of our MQGs are consistent with the slope and the location of the Main Sequence (MS) of star-forming galaxies at $z$ $>$ 1.0, when our galaxies were 0.5-1.0 Gyr old. According to these SFHs, all the MQGs experienced a Luminous Infrared Galaxy (LIRG) phase that lasts for $\sim$ 500 Myr, and half of them an Ultra Luminous Infrared Galaxy (ULIRG) phase for $\sim$ 100 Myr. We find that the MQG population is almost assembled at $z$ $\sim$ 1, and continues evolving passively with few additions to the population., Comment: 26 pages, 18 figures. Accepted for publication in MNRAS

Published
2015
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407. Evolution of the Sizes of Galaxies over 7 < z < 12 Revealed by the 2012 Hubble Ultra Deep Field Campaign

Author

Ono, Yoshiaki, Ouchi, Masami, Curtis-Lake, Emma, Schenker, Matthew A., Ellis, Richard S., McLure, Ross J., Dunlop, James S., Robertson, Brant E., Koekemoer, Anton M., Bowler, Rebecca A. A., Rogers, Alexander B., Schneider, Evan, Charlot, Stéphane, Stark, Daniel P., Shimasaku, Kazuhiro, Furlanetto, Steven R., and Cirasuolo, Michele

Subjects
Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We analyze the redshift- and luminosity-dependent sizes of dropout galaxy candidates in the redshift range z ~ 7-12 using deep images from the 2012 Hubble Ultra Deep Field (UDF12) campaign, which offers two advantages over that used in earlier work. First, we utilize the increased signal-to-noise ratio offered by the UDF12 imaging to provide improved measurements for known galaxies at z ≃ 6.5-8 in the HUDF. Second, because the UDF12 data have allowed the construction of the first robust galaxy sample in the HUDF at z > 8, we have been able to extend the measurement of average galaxy size out to higher redshifts. Restricting our measurements to sources detected at >15σ, we confirm earlier indications that the average half-light radii of z ~ 7-12 galaxies are extremely small, 0.3-0.4 kpc, comparable to the sizes of giant molecular associations in local star-forming galaxies. We also confirm that there is a clear trend of decreasing half-light radius with increasing redshift, and provide the first evidence that this trend continues beyond z ≃ 8. Modeling the evolution of the average half-light radius as a power law, ∝(1 + z)^s , we obtain a best-fit index of s = -1.30^(+0.12)_(-0.14) over z ~ 4-12. A clear size-luminosity relation is evident in our dropout samples. This relation can be interpreted in terms of a constant surface density of star formation over a range in luminosity of 0.05-1.0L^*_(z=3). The average star formation surface density in dropout galaxies is 2-3 orders of magnitude lower than that found in extreme starburst galaxies, but is comparable to that seen today in the centers of normal disk galaxies.

Published
2013

408. Caractérisation radiofréquence et amélioration de l’architecture d’un boîtier DHVQFN pour des applications micro-ondes

Author

Charlot, Stéphane, Centre d'enseignement Cnam Basse Normandie (CNAM Basse-Normandie), and Conservatoire National des Arts et Métiers [CNAM] (CNAM)

Subjects
Radiofrequency measurements, Parasitic extraction, Extraction de parasites, [SPI]Engineering Sciences [physics], Package, Caractérisation sous pointes, Electromagnetic simulation, Mesures radiofréquences, Boîtier, On-wafer characterization, Simulations électromagnétiques
Abstract

The "Packaging Innovation" project aims to investigate new package solutions based on existing satellite products in order to develop future microwave applications. The goal of this paper is to present the work I did inside this project. It is divided in two parts: the first was to design an original radiofrequency characterization method for mounted plastic package using wire bonding in order to show their actual electrical limitation in microwave frequency domain. The second step was to use an EM simulator, after a solid calibration step, to evaluate and suggest improvements in order to target these microwave applications. Regarding the EM results analysis, we can conclude that the simulator, correctly calibrated, could be use as reference to investigate improvements. A novel package approach was evaluated by EM simulation and seems to be the right candidate for target microwave applications. The next step will be to measure demonstrators which will be available soon to validate this approach.; Le projet "Packaging Innovation" a pour finalité d’investiguer de nouvelles solutions de boîtiers basées sur des produits satellites existants dans le but de développer les futures applications microondes. L’objectif de ce mémoire est de présenter le travail que j’ai réalisé au sein de ce projet. Il se décompose en deux parties : la première a été de concevoir une méthode originale de caractérisation radiofréquence de boitiers dans le but de démontrer les limitations électriques des boîtiers plastiques filaires dans le domaine des hautes fréquences. La seconde étape fût d’utiliser un simulateur EM, après une solide étape de calibrage, pour évaluer et proposer des pistes d’améliorations au niveau de l’architecture des boitiers dans le but de viser les applications d’ondes centimétriques. L’analyse des résultats de simulations EM a permis de conclure que le simulateur correctement calibré peut être utilisé comme référence pour des évaluations. Une nouvelle structure de boitier a été évaluée par simulations et semble être un bon candidat pour les futures applications. La prochaine étape sera de valider cette nouvelle approche de boitier sur des mesures d’échantillons qui seront disponibles prochainement.

Published
2011

409. Spectroscopic detection of C iv λ1548 in a galaxy atz = 7.045: implications for the ionizing spectra of reionization-era galaxies

Author

Stark, Daniel P., primary, Walth, Gregory, additional, Charlot, Stéphane, additional, Clément, Benjamin, additional, Feltre, Anna, additional, Gutkin, Julia, additional, Richard, Johan, additional, Mainali, Ramesh, additional, Robertson, Brant, additional, Siana, Brian, additional, Tang, Mengtao, additional, and Schenker, Matthew, additional

Published
2015
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414. On the importance of using appropriate spectral models to derive physical properties of galaxies at 0.7 < z < 2.8

Author

Pacifici, Camilla, primary, da Cunha, Elisabete, additional, Charlot, Stéphane, additional, Rix, Hans-Walter, additional, Fumagalli, Mattia, additional, Wel, Arjen van der, additional, Franx, Marijn, additional, Maseda, Michael V., additional, van Dokkum, Pieter G., additional, Brammer, Gabriel B., additional, Momcheva, Ivelina, additional, Skelton, Rosalind E., additional, Whitaker, Katherine, additional, Leja, Joel, additional, Lundgren, Britt, additional, Kassin, Susan A., additional, and Yi, Sukyoung K., additional

Published
2014
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415. THE STELLAR INITIAL MASS FUNCTION AT 0.9 < z < 1.5

Author

Martín-Navarro, Ignacio, primary, Pérez-González, Pablo G., additional, Trujillo, Ignacio, additional, Esquej, Pilar, additional, Vazdekis, Alexandre, additional, Sánchez, Helena Domínguez, additional, Barro, Guillermo, additional, Bruzual, Gustavo, additional, Charlot, Stéphane, additional, Cava, Antonio, additional, Ferreras, Ignacio, additional, Espino, Néstor, additional, Barbera, Francesco La, additional, Koekemoer, Anton M., additional, and Cenarro, A. Javier, additional

Published
2014
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417. Stellar population study in early-type galaxies

Author

Mármol-Queraltó, Esther, Cardiel, Nicolás, Sánchez-Blázquez, P., Trager, S.C., Peletier, R.F., Kuntschner, H., R. Silva, D., J. Cenarro, A., Vazdekis, A., Gorgas, J., Bruzual, Gustavo, Charlot, Stéphane, and Astronomy

Subjects
Luminous infrared galaxy, Physics, Stellar population, Infrared, Astronomy, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Stellar classification, Spectral line, Galaxy, Stars, Space and Planetary Science, cD — galaxies: evolution — galaxies: formation — galaxies: stellar content, Astrophysics::Solar and Stellar Astrophysics, Fornax Cluster, galaxies: clusters: general — galaxies: elliptical and lenticular, Astrophysics::Galaxy Astrophysics
Abstract

A full understanding of the physical properties of integrated stellar systems demands a multiwavelength approach since each spectral window shows us the contribution of different types of stars. However, most of the observational effort in stellar population studies has been focused on the optical range. Now, the new generation of instruments allow us to explore the K band, where RGB and AGB stars dominate the light of the integrated spectra. Here we present a K-band spectroscopic analysis of early-type galaxies in different environments. Our sample comprises 12 field early-type galaxies observed with ISAAC at VLT with medium resolution, and they are compared with 11 Fornax cluster galaxies previously reported by Silva et al. (2008). The clear differences found in the infrared DCO and NaI indices between field and Fornax galaxies are discussed, trying to solve the puzzle formed by the near-infrared and optical measurements.

Published
2009

418. The cosmic star formation rate evolution from z = 5 to z = 0 from the VIMOS VLT deep survey

Author

Tresse, Laurence, Ilbert, Olivier, Zucca, E., Zamorani, G., Bardelli, Sandro, Arnouts, S., Paltani, S., Pozzetti, L., Bottini, D., Garilli, Bianca, Le Brun, V., Le Fèvre, Olivier, Maccagni, D., Picat, J.-P., Scaramella, R., Scodeggio, Marco, Vettolani, G., Zanichelli, A., Adami, C., Arnaboldi, M., Bolzonella, M., Cappi, A., Charlot, Stéphane, Ciliegi, Paolo, Contini, Thierry, Foucaud, S., Franzetti, P., Gavignaud, I., Guzzo, L., Iovino, Angela, Mccracken, Henry J., Marano, B., Marinoni, Christian, Mazure, A., Meneux, Baptiste, Merighi, R., Pello, R., Pollo, Agnieszka, Radovich, M., Bondi, M., Bongiorno, Angela, Busarello, G., Cucciati, O., Lamareille, Fabrice, Mathez, G., Mellier, Yannick, Merluzzi, P., Ripepi, V., Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institute for Astronomy, University of Hawaii, INAF-Osservatorio Astronomico di Bologna (OABO), INTEGRAL Science Data Centre, Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF-Milano), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Istituto di Radioastronomia, Bologna, INAF-Osservatorio Astronomico di Roma (INAF-OAR), INAF-Osservatorio Astronomico di Capodimonte (INAF-OAC), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy, University of Nottingham, Astrophysikalisches Institut Potsdam (AIP), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Centre de Physique Théorique - UMR 7332 (CPT), and Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Context: The VIMOS VLT Deep Survey (VVDS) was undertaken to map the evolution of galaxies, large scale structures, and active galaxy nuclei from the redshift spectroscopic measurements of ~105 objects down to an apparent magnitude IAB = 24, in combination with a multi-wavelength acquisition for radio, infrared, optical, ultraviolet, and X-rays data. Aims: We present the evolution of the comoving star formation rate (SFR) density in the redshift range 0 < z < 5 using the first epoch data release of the VVDS, that is 11564 spectra over 2200 arcmin2 in two fields of view, the VVDS-0226-04 and the VVDS-CDFS-0332-27, and the cosmological parameters (Omega_M, OmegaLambda, h)=(0.3, 0.7, 0.7). Methods: We study the multi-wavelength non dust-corrected luminosity densities at 0 < z < 2 from the rest-frame far ultraviolet to the optical passbands, and the rest-frame 1500 Å luminosity functions and densities at 2.7 < z < 5. Results: They evolve from z=1.2 to z=0.05 according to (1+z)x with x = 2.05, 1.94, 1.92, 1.14, 0.73, 0.42, and 0.30 in the FUV-1500, NUV-2800, U-3600, B-4400, V-5500, R-6500, and I-7900 passbands, respectively. From z=1.2 to z=0.2 the B-band density for the irregular-like galaxies decreases markedly by a factor 3.5 while it increases by a factor 1.7 for the elliptical-like galaxies. We identify several SFR periods; from z=5 to 3.4 the FUV-band density increases by at most 0.5 dex, from z=3.4 to 1.2 it decreases by 0.08 dex, from z=1.2 to z=0.05 it declines steadily by 0.6 dex. For the most luminous MAB(1500 Å)

Published
2007

419. Spectrophotometric properties of galaxies at intermediate redshifts (z\textasciitilde{}0.2--1.0) II. The Luminosity -- Metallicity relation

Author

Lamareille, Fabrice, Contini, Thierry, Brinchmann, Jarle, Le Borgne, Jean-François, Charlot, Stéphane, Richard, Johan, Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto, Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universidade do Porto = University of Porto, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], galaxies: abundances, galaxies: fundamental parameters, galaxies: starburst, Astrophysics::Cosmology and Extragalactic Astrophysics, galaxies: evolution, Astrophysics::Galaxy Astrophysics
Abstract

19 pages. Accepted for publication on A&A; reference added; bug corrected: flux scaled by (1+z); We present the gas-phase oxygen abundance (O/H) for a sample of 131 star-forming galaxies at intermediate redshifts ($0.2

Published
2006

420. Variations of the stellar initial mass function in semi-analytical models: implications for the mass assembly and the chemical enrichment of galaxies in the GAEA model.

Author

Fontanot, Fabio, De Lucia, Gabriella, Hirschmann, Michaela, Bruzua, Gustavo, Charlot, Stéphane, and Zibetti, Stefano

Subjects
STELLAR mass, ASTRONOMICAL observations, STELLAR evolution, FEEDBACK control systems, ASTRONOMICAL research
Abstract

In this paper, we investigate the implications of the integrated galaxy-wide stellar initial mass function (IGIMF) approach in the framework of the semi-analytical model GAEA (GAlaxy Evolution and Assembly), which features a detailed treatment of chemical enrichment and stellar feedback. The IGIMF provides an analytic description of the dependence of the stellar IMF shape on the rate of star formation in galaxies. We find that our model with a universal IMF predicts a rather flat [α/Fe]-stellar mass relation. The model assuming the IGIMF, instead, is able to reproduce the observed increase of α-enhancement with stellar mass, in agreement with previous studies. This is mainly due to the fact that massive galaxies are characterized by larger star formation rates at high redshift, leading to stronger α-enhancement with respect to low-mass galaxies. At the same time, the IGIMF hypothesis does not affect significantly the trend for shorter star formation time-scales for more massive galaxies. We argue that in the IGIMF scenario the [α/Fe] ratios are good tracers of the highest star formation events. The final stellar masses and mass-to-light ratio of our model massive galaxies are larger than those estimated from the synthetic photometry assuming a universal IMF, providing a self-consistent interpretation of similar recent results, based on dynamical analysis of local early-type galaxies. [ABSTRACT FROM AUTHOR]

Published
2017
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421. Lyα and CIII] emission in z = 7-9 Galaxies: accelerated reionization around luminous star-forming systems?

Author

Stark, Daniel P., Ellis, Richard S., Charlot, Stéphane, Chevallard, Jacopo, Tang, Mengtao, Belli, Sirio, Zitrin, Adi, Mainali, Ramesh, Gutkin, Julia, Vidal-García, Alba, Bouwens, Rychard, and Oesch, Pascal

Subjects
GALAXIES, STELLAR evolution, REDSHIFT, ASTRONOMICAL observations, LUMINOSITY, METAPHYSICAL cosmology
Abstract

We discuss new Keck/MOSFIRE spectroscopic observations of four luminous galaxies at z ... 7-9 selected to have intense optical line emission by Roberts-Borsani et al. Previous followup has revealed Lyα in two of the four galaxies. Our new MOSFIRE observations confirm that Lyα is present in the entire sample. We detect Lyα emission in the galaxy COS-zs7-1, confirming its redshift as zLyα = 7.154, and we detect Lyα in EGS-zs8-2 at zLyα = 7.477, verifying an earlier tentative detection. The ubiquity of Lyα in this sample is puzzling given that the IGM is expected to be significantly neutral over 7 < z < 9. To investigate this result in more detail, we have initiated a campaign to target UV metal lines in the four Lyα emitters as a probe of both the ionizing field and the Lyα velocity offset at early times. Here we present the detection of C III] emission in the z = 7.73 galaxy EGS-zs8-1, requiring an intense radiation field and moderately low metallicity. We argue that the radiation field is likely to affect the local environment, increasing the transmission of Lyα through the galaxy.Moreover, the centroid of CIII] indicates that Lyα is redshifted by 340 km s-1. This velocity offset is larger than that seen in less luminous systems, providing an explanation for the transmission of Lyα emission through the IGM. Since the transmission is further enhanced by the likelihood that such systems are also situated in large ionized bubbles, the visibility of Lyα at z > 7 is expected to be strongly luminosity-dependent, with transmission accelerated in systems with intense star formation. [ABSTRACT FROM AUTHOR]

Published
2017
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426. ACTIVE GALACTIC NUCLEI EMISSION LINE DIAGNOSTICS AND THE MASS-METALLICITY RELATION UP TO REDSHIFTz∼ 2: THE IMPACT OF SELECTION EFFECTS AND EVOLUTION

Author

Juneau, Stéphanie, primary, Bournaud, Frédéric, additional, Charlot, Stéphane, additional, Daddi, Emanuele, additional, Elbaz, David, additional, Trump, Jonathan R., additional, Brinchmann, Jarle, additional, Dickinson, Mark, additional, Duc, Pierre-Alain, additional, Gobat, Raphael, additional, Jean-Baptiste, Ingrid, additional, Le Floc'h, Émeric, additional, Lehnert, M. D., additional, Pacifici, Camilla, additional, Pannella, Maurilio, additional, and Schreiber, Corentin, additional

Published
2014
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429. Pathways to quiescence: SHARDS view on the star formation histories of massive quiescent galaxies at 1.0 < z < 1.5.

Author

Sánchez, Helena Domínguez, Pérez-González, Pablo G., Esquej, Pilar, Eliche-Moral, M. Carmen, Barro, Guillermo, Cava, Antonio, Koekemoer, Anton M., Pampliega, Belén Alcalde, Herrero, Almudena Alonso, Bruzual, Gustavo, Cardiel, Nicolás, Cenarro, Javier, Ceverino, Daniel, Charlot, Stéphane, and Caballero, Antonio Hernán

Subjects
STAR formation, MONTE Carlo method, GALACTIC redshift, STELLAR mass, SPECTRAL energy distribution, ULTRAVIOLET radiation, SUPERGIANT stars
Abstract

We present star formation histories (SFHs) for a sample of 104 massive (stellar mass M > 1010 M⊙) quiescent galaxies (MQGs) at z = 1.0-1.5 from the analysis of spectrophotometric data from the Survey for High-z Absorption Red and Dead Sources (SHARDS) and HST/WFC3 G102 and G141 surveys of the GOODS-North field, jointly with broad-band observations from ultraviolet (UV) to far-infrared (far-IR). The sample is constructed on the basis of rest-frame UVJ colours and specific star formation rates (sSFRs = SFR/Mass). The spectral energy distributions (SEDs) of each galaxy are compared to models assuming a delayed exponentially declining SFH. A Monte Carlo algorithm characterizes the degeneracies, which we are able to break taking advantage of the SHARDS data resolution, by measuring indices such as MgUV and D4000. The population of MQGs shows a duality in their properties. The sample is dominated (85 per cent) by galaxies with young mass-weighted ages, tM < 2 Gyr, short star formation time-scales, <τ> ~ 60-200 Myr, and masses log(M/M⊙) ~ 10.5. There is an older population (15 per cent) with tM = 2-4 Gyr, longer star formation time-scales, <τ> ~ 400 Myr, and larger masses, log(M/M⊙) ~ 10.7. The SFHs of our MQGs are consistent with the slope and the location of the main sequence of star-forming galaxies at z > 1.0, when our galaxies were 0.5-1.0 Gyr old. According to these SFHs, all the MQGs experienced a luminous infrared galaxy phase that lasts for ~500 Myr, and half of them an ultraluminous infrared galaxy phase for ~100 Myr. We find that the MQG population is almost assembled at z ~ 1, and continues evolving passively with few additions to the population. [ABSTRACT FROM AUTHOR]

Published
2016
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430. Spectroscopic detection of CIV λ1548 in a galaxy at z = 7.045: implications for the ionizing spectra of reionization-era galaxies.

Author

Stark, Daniel P., Walth, Gregory, Charlot, Stéphane, Clément, Benjamin, Feltre, Anna, Gutkin, Julia, Richard, Johan, Mainali, Ramesh, Robertson, Brant, Siana, Brian, Mengtao Tang, and Schenker, Matthew

Subjects
GALAXIES, STELLAR evolution, STELLAR populations, NEBULAE, SPECTROMETRY, ASTRONOMICAL research
Abstract

We presentKeck/MOSFIRE observations of UV metal emission lines in four bright (H=23.9. 25.4) gravitationally lensed z ≃ 6-8 galaxies behind the cluster Abell 1703. The spectrum of A1703-zd6, a highly magnified star-forming galaxy with a Lyα redshift of z = 7.045, reveals a confident detection of the nebular CIV λ1548 emission line (unresolved with full width at halfmaximum< 125 km s-1). UV metal emission lines are not detected in the three other galaxies. At z ≃ 2.3, nebular CIV emission is observed in just 1 per cent of UV-selected galaxies. The presence of strong C IV emission in one of the small sample of galaxies targeted in this paper may indicate that hard ionizing spectra are more common at z ≃ 7. The total estimated rest-frame equivalent width of the CIV doublet and CIV/Lyƒα flux ratio are comparable to measurements of narrow-lined AGNs. Photoionization models show that the nebular C IV line can also be reproduced by a young stellar population, with very hot metal-poor stars dominating the photon flux responsible for triply ionizing carbon. Regardless of the origin of the CIV, we show that the ionizing spectrum of A1703-zd6 is different from that of typical galaxies at z2, producing more H ionizing photons per unit 1500 Å luminosity (log(Eion/erg-1 Hz) = 25.68) and a larger flux density at 30.50 eV. If such extreme radiation fields are typical in UV-selected systems at z ≳ 7, it would indicate that reionization-era galaxies are more efficient ionizing agents than previously thought. Alternatively, we suggest that the small sample of Lyα emitters at z ≳ 7 may trace a rare population with intense radiation fields capable of ionizing their surrounding hydrogen distribution. Additional constraints on high-ionization emission lines in galaxies with and without Lyα detections will help clarify whether hard ionizing spectra are common in the reionization era. [ABSTRACT FROM AUTHOR]

Published
2015
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431. SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES

Author

Pérez-González, Pablo G., primary, Cava, Antonio, additional, Barro, Guillermo, additional, Villar, Víctor, additional, Cardiel, Nicolás, additional, Ferreras, Ignacio, additional, Rodríguez-Espinosa, José Miguel, additional, Alonso-Herrero, Almudena, additional, Balcells, Marc, additional, Cenarro, Javier, additional, Cepa, Jordi, additional, Charlot, Stéphane, additional, Cimatti, Andrea, additional, Conselice, Christopher J., additional, Daddi, Emmanuele, additional, Donley, Jennifer, additional, Elbaz, David, additional, Espino, Néstor, additional, Gallego, Jesús, additional, Gobat, R., additional, González-Martín, Omaira, additional, Guzmán, Rafael, additional, Hernán-Caballero, Antonio, additional, Muñoz-Tuñón, Casiana, additional, Renzini, Alvio, additional, Rodríguez-Zaurín, Javier, additional, Tresse, Laurence, additional, Trujillo, Ignacio, additional, and Zamorano, Jaime, additional

Published
2012
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433. A database for galaxy evolution modeling

Author

Leitherer, Claus, Alloin, Danielle, Alvensleben, Uta Fritze-V, Gallagher, John, Huchra, John, Matteucci, Francesca, O'Connell, Robert, Beckman, John, Bica, Eduardo, Boisson, Catherine, Bonatto, Charles, Bothun, Gregory, Bressan, Alessandro, Brodie, Jean, Bruzual, Gustavo, Burstein, David, Caldwell, Nelson, Casuso, Emilio, Cervino, Miguel, Charlot, Stéphane, Chavez, Miguel, Chiosi, Cesare, Christiane, Carol, Dallier, Richard, Delisle, Sonya, Diaz, Angeles, Dopita, Michael, Dorman, Ben, Fanelli, Michael, Fioc, Michel, Garciavargas, Maria Luisa, Goldader, Jeffrey, Hardy, Eduardo, Heckman, Timothy, Iglesias, Jorge, Jablonka, Pascale, Joly, Monique, Jones, Lewis, Lançon, Ariane, Lejeune, Thibault, Maeder, André, Malagnini, Maria Lucia, Mas-Hesse, J. Miguel, Meynet, Georges, Mollâ, Mercedes, Morossi, Carlo, Nichols, Joy, Odegaard, Knut, Panek, Robert, Parker, Joel, Pastoriza, Miriani, Peletier, Reynier, Robert, Carmelle, Rocca-Volmerange, Brigitte, Schaerer, Daniel, Schmidt, Alex, Schmitt, Henrique, Schommer, Robert, Schmutz, Werner, Serote Roos, Margarida, Stasinska, Grazyna, Sutherland, Ralph, Tantalo, Rosaria, Traat, Peeter, Vazdekis, Alexandre, Walborn, Nolan, Worthey, Guy, Wu, Chi-Chao, Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and Dallier, Richard

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Stars: evolution, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Galaxies: evolution, astronomical databases, Astrophysics::Cosmology and Extragalactic Astrophysics, [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph], stellar content, fundamental parameters
Abstract

This paper represents a collective effort to provide an extensive electronic database useful for the interpretation of galaxy properties.

Published
1996

435. The LF of TP-AGB stars in the LMC/SMC

Author

Bruzual, Gustavo, primary, Charlot, Stéphane, additional, Lópezlira, Rosa González, additional, Srinivasan, Sundar, additional, Boyer, Martha L., additional, and Riebel, David, additional

Published
2012
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436. SSGSS: THESPITZER–SDSS–GALEXSPECTROSCOPIC SURVEY

Author

O’Dowd, Matthew J., primary, Schiminovich, David, additional, Johnson, Benjamin D., additional, Treyer, Marie A., additional, Martin, Christopher D., additional, Wyder, Ted K., additional, Charlot, Stéphane, additional, Heckman, Timothy M., additional, Martins, Lucimara P., additional, Seibert, Mark, additional, and van der Hulst, J. M., additional

Published
2011
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441. DUST ATTENUATION IN UV-SELECTED STARBURSTS AT HIGH REDSHIFT AND THEIR LOCAL COUNTERPARTS: IMPLICATIONS FOR THE COSMIC STAR FORMATION RATE DENSITY

Author

Overzier, Roderik A., primary, Heckman, Timothy M., additional, Wang, Jing, additional, Armus, Lee, additional, Buat, Veronique, additional, Howell, Justin, additional, Meurer, Gerhardt, additional, Seibert, Mark, additional, Siana, Brian, additional, Basu-Zych, Antara, additional, Charlot, Stéphane, additional, Gonçalves, Thiago S., additional, Martin, D. Christopher, additional, Neill, James D., additional, Rich, R. Michael, additional, Salim, Samir, additional, and Schiminovich, David, additional

Published
2010
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443. DIORAMAS: a wide-field visible and near-infrared imaging multi-slit spectrograph for the EELT

Author

Le Fèvre, Olivier, primary, Maccagni, Dario, additional, Paltani, Stéphane, additional, Hill, Lucien, additional, Le Mignant, David, additional, Tresse, Laurence, additional, Garzon Lopez, Francisco, additional, Almaini, Omar, additional, Brinchmann, Jarle, additional, Charlot, Stéphane, additional, Ciardi, Benedetta, additional, Fontana, Adriano, additional, Gallego, Jesus, additional, Garilli, Bianca, additional, Ilbert, Olivier, additional, Meneux, Baptiste, additional, de Caprio, Vincenzo, additional, Delabre, Bernard, additional, Genolet, Ludovic, additional, Jaquet, Marc, additional, Martin, Laurent, additional, Roman, Florence, additional, and Rousset, Gérard, additional

Published
2010
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450. MID-IR LUMINOSITIES AND UV/OPTICAL STAR FORMATION RATES ATz< 1.4

Author

Salim, Samir, primary, Dickinson, Mark, additional, Michael Rich, R., additional, Charlot, Stéphane, additional, Lee, Janice C., additional, Schiminovich, David, additional, Pérez-González, Pablo G., additional, Ashby, Matthew L. N., additional, Papovich, Casey, additional, Faber, S. M., additional, Ivison, Rob J., additional, Frayer, David T., additional, Walton, Josiah M., additional, Weiner, Benjamin J., additional, Chary, Ranga-Ram, additional, Bundy, Kevin, additional, Noeske, Kai, additional, and Koekemoer, Anton M., additional

Published
2009
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