WorldCat Identities

Palanque-Delabrouille, Nathalie

Overview
Works: 9 works in 14 publications in 2 languages and 54 library holdings
Genres: Observations  Catalogs 
Roles: Author, Thesis advisor, Opponent, Interviewee
Publication Timeline
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Most widely held works by Nathalie Palanque-Delabrouille
Les nouveaux messagers du cosmos by Nathalie Palanque-Delabrouille( Book )

3 editions published in 2011 in French and held by 43 WorldCat member libraries worldwide

Research on galactic dark matter implied by gravitational microlensing by Nathalie Palanque-Delabrouille( )

3 editions published between 1997 and 1998 in English and held by 3 WorldCat member libraries worldwide

Energie noire et matière noire by Nathalie Palanque-Delabrouille( Visual )

2 editions published between 2011 and 2013 in French and held by 2 WorldCat member libraries worldwide

One-Dimensional Power Spectrum and Neutrino Mass in the Spectra of BOSS by Arnaud Borde( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

The framework of the studies presented in this thesis is the one-dimensional power spectrum of the transmitted flux in the Lyman-alpha forests. The Lyman-alpha forest is an an absorption pattern seen in the spectra of high redshift quasars corresponding to the absorption of the quasar light by the hydrogen clouds along the line of sight. It is a powerful cosmological tool as it probes relatively small scales, of the order of a few Mpc. It is also sensible to small non-linear effects such as the one induced by massive neutrinos.First, we have developed two independent methods to measure the one-dimensional power spectrum of the transmitted flux in the Lyman-alpha forest. The first method is based on a Fourier transform, and the second on a maximum likelihood estimator. The two methods are independent and have different systematic uncertainties. The determination of the noise level in the data spectra was subject to a novel treatment, because of its significant impact on the derived power spectrum. We applied the two methods to 13,821 quasar spectra from SDSS-III/BOSS DR9 selected from a larger sample of over 60,000 spectra on the basis of their high quality, large signal-to-noise ratio, and good spectral resolution. The power spectra measured using either approach are in good agreement over all twelve redshift bins from <z>=2.2 to <z>=4.4, and scales from 0.001 (km/s)^-1 to 0.02 (km/s)^-1. We carefully determined the methodological and instrumental systematic uncertainties of our measurements.Then, we present a suite of cosmological N-body simulations with cold dark matter, baryons and neutrinos aiming at modeling the low-density regions of the IGM as probed by the Lyman-alpha forests at high redshift. The simulations are designed to match the requirements imposed by the quality of BOSS and eBOSS data. They are made using either 768^3 or 192^3 particles of each type, spanning volumes ranging from (25 Mpc/h)^3 for high-resolution simulations to (100 Mpc/h)^3 for large-volume ones. Using a splicing technique, the resolution is further enhanced to reach the equivalent of simulations with 3072^3 = 29 billion particles of each type in a (100 Mpc/h)^3 box size, i.e. a mean mass per gas particle of 1.2x10^5 solar masses. We show that the resulting power spectrum is accurate at the 2% level over the full range from a few Mpc to several tens of Mpc. We explore the effect on the one-dimensional transmitted-flux power spectrum of 4 cosmological parameters (n_s, sigma_8, Omega_m ,H_0), 2 astrophysical parameters (T_0, gamma) related to the heating rate of the IGM and the sum of the neutrino masses. By varying the input parameters around a central model chosen to be in agreement with the latest Planck results, we built a grid of simulations that allows the study of the impact on the flux power spectrum of these seven relevant parameters. We improve upon previous studies by not only measuring the effect of each parameter individually, but also probing the impact of the simultaneous variation of each pair of parameters. We thus provide a full second-order expansion, including cross-terms, around our central model. We check the validity of the second-order expansion with independent simulations obtained either with different cosmological parameters or different seeds for the initial condition generation. Finally, a comparison to the one-dimensional Lyman-alpha forest power spectrum obtained in the first part with BOSS data shows an excellent agreement.Eventually, even if there are still some potential biases and systematic errors that need to be studied in our simulation, we performed cosmological fits combining our measurement of the one-dimensional power spectrum and other cosmological probes such as the CMB results provided by Planck. These preliminary results are very encouraging as they lead to some of the tighest cosmological constraints as of today, especially on the sum of the neutrino masses with an upper limit of 0.1 eV
The one-dimensional Ly[alpha] forest power spectrum from BOSS( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

Analyse différée des données de SNLS : mesure des paramètres cosmologiques et du taux d'explosion des supernovae de type Ia by Vincent Lusset( Book )

1 edition published in 2006 in French and held by 1 WorldCat member library worldwide

The Supernova Legacy Survey is a second generation experiment for the measurement of cosmological parameters using type-la supernovae . Il follows the discovery of the acceleration of the expansion of the Universe, attributed to an unknown "dark energy". This thesis presents a type-la supernovae search using an offline analysis of SNLS data. It makes it possible to detect the supernovae that were missed online and to study possible selection biases. One of its principal characteristics is that it uses entirely automatic selection criteria. This type of automated offline analysis had never been carried out before for data reaching this redshift. This analysis enabled us to discover 73 additional SNIa candidates compared to those identified in the real time analysis on the same data, representing an increase of more than 50% of the number of supernovae . The final Hubble diagram contains 262 SNIa which gives us, for a flat ACDM model, the following values for the cosmological parameters: DM = 0,31 ± 0,028 (stat) ± 0,036 (syst) et ÛA = 0,69. This offline analysis of SNLS data opens new horizons, both by checking for possible biases in current measurements of cosmological parameters by supernovae experiments and by preparing the third generation experiments, on the ground or in space, which will detect thousands of SNIa
The eighth data release of the Sloan Digital Sky Survey : first data from SDSS-III by Hiroaki Aihara( Book )

1 edition published in 2011 in English and held by 1 WorldCat member library worldwide

"The Sloan Digital Sky Survey (SDSS) started a new phase in 2008 August, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly[Greek letter alpha] forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg2 in the southern Galactic cap, bringing the total footprint of the SDSS imaging to 14,555 deg2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Exploration (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameter pipeline, which has better determinationof metallicity for high-metallicity stars."
Détermination de la masse des neutrinos cosmologiques avec les forêts Lyman-alpha by Julien Baur( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

Les travaux présentés dans cette thèse contraignent la masse des neutrinos dans le contexte de 4 modèles de matière noire en utilisant le spectre de puissance du flux transmit dans les forêts Lyman-alpha des quasars distants. Les neutrinos laissent une emprunte sur les grandes structures dans l'Univers à travers l'échelle à laquelle ils diffusent, qui se manifeste comme un déficit de fluctuations de densité de matière sur des distances inversement proportionnelles à leur masse. De l'ordre de quelques Mpc, ces échelles peuvent être sondées par les forêts Ly-$alpha$ qui tracent la densité d'hydrogène neutre atomique suivant la ligne de visée du quasar en arrière-plan. J'utilise le spectre de puissance Ly-$alpha$ construit grâce à deux relevés de grandes structures:les $13,821$ spectres optiques de quasars basse-résolution de la 9ème publication des données du SDSS/BOSS à 12 redshifts de $langle z rangle = 2.2$ à $4.4$; ainsi que la centaine de spectres de quasar haute-résolution du relevé XQ-100 du VLT à $langle z rangle = 3.20, 3.56$ et $3.93$. Ces deux relevés nous permettent de sonder les échelles de $k geqslant 0.001~s/mathrm{km}$ à $k leqslant 0.02$ et $k leqslant 0.07~ s/mathrm{km}$ respectivement.Modéliser le spectre de puissance Ly-$alpha$ nécessite résoudre le régime non-linéaire de formation des structure et modéliser le gaz inter-galactique dans les simulations cosmologiques hydrodynamiques destinées à cet effet. Je contrôle pour plusieurs incertitudes systématiques liées à ces simulations. Dans un premier temps, je quantifie la variance d'échantillonnage à l'aide de simulations tournées avec différentes conditions initiales. Dans un second temps, je teste la validité d'une méthode permettant de construire le spectre de puissance à partir de simulations plus petites et moins résolues. Pour ce, j'ai tourné une simulation évoluant $2 times 2048^3$ particules de matière noire et de baryons dans un covolume de $(100~h^{-1}mathrm{Mpc})^3$. Ce travail a permit à notre groupe d'améliorer les contraintes sur la masse des neutrinos de $sum m_nu < 0.15~mathrm{eV}$ établie précédemment à $sum m_nu < 0.12~mathrm{eV}$ à $95%$ de vraisemblance. J'ai ensuite tourné mes efforts vers l'implémentation de neutrinos stériles en tant qu'un candidat matière noire non-froide dans les simulations. En particulier, j'ai produit les contraintes les plus fortes (au moment de la publication) sur la masse des neutrinos stériles en tant que matière noire tiède: $m_nu lesssim 25~mathrm{keV}$ à $95%$ de vraisemblance. J'ai étendu l'étude dans le contexte d'une matière noire mixte et contraint l'abondance relative de la composante tiède par rapport à la froide. Enfin, j'ai complété ce travail en permettant une résonance dans la production des neutrinos stériles, réduisant ainsi leur échelle caractéristique de diffusion et refroidissant la matière tiède qu'ils incorporent. A ce but, j'ai initié une collaboration avec une équipe de physiciens théoriques impliqués dans les recherches astrophysiques de ces neutrinos stériles dits produits par résonance dans des objets riches en matière noire. Notre jeune collaboration a établi les premières contraintes sur leur masse en utilisant le spectre de puissance Ly-$alpha$
RECHERCHE DE MATIERE NOIRE GALACTIQUE PAR EFFET DE MICROLENTILLE GRAVITATIONNELLE by Nathalie Palanque-Delabrouille( Book )

1 edition published in 1997 in French and held by 1 WorldCat member library worldwide

L'UNE DES PREUVES LES PLUS CONVAINCANTES DE L'EXISTENCE DE MATIERE NOIRE PROVIENT DE L'ETUDE DES COURBES DE ROTATION DES GALAXIES SPIRALES. LA MASSE DYNAMIQUE QUE L'ON EN DEDUIT EST ENVIRON TROIS FOIS SUPERIEURE A LA COMPOSANTE VISIBLE. APRES AVOIR RESUME L'ENSEMBLE DE LA PROBLEMATIQUE DE LA MATIERE NOIRE, NOUS MONTRERONS QUE LES HALOS GALACTIQUES POURRAIENT ETRE COMPOSES D'OBJETS COMPACTS BARYONIQUES. EN RECHERCHANT PENDANT 4 ANS DES EFFETS DE MICROLENTILLE GRAVITATIONNELLE SUR DES ETOILES DES NUAGES DE MAGELLAN, L'EXPERIENCE EROS A EXCLU QUE DES OBJETS DE 5E-7 A 0.02 MASSE SOLAIRE CONSTITUENT PLUS DE 20% DU HALO STANDARD. EROS2 RECHERCHE DES MASSES PLUS ELEVEES ET EXPLORE UNE NOUVELLE LIGNE DE VISEE : LE PETIT NUAGE DE MAGELLAN. NOUS EXPOSERONS SES OBJECTIFS SCIENTIFIQUES, PRESENTERONS LE DISPOSITIF EXPERIMENTAL, LA CHAINE D'ACQUISITION, ET LES LOGICIELS D'ANALYSE, OU UN NOUVEL ALGORITHME DE DETECTION PERMET D'AUGMENTER CONSIDERABLEMENT LE NOMBRE D'ETOILES SUIVIES. NOUS DECRIRONS EN DETAIL L'ANALYSE DE LA PREMIERE ANNEE DE DONNEES VERS LE SMC (5 MILLIONS DE COURBES DE LUMIERE), QUI MET EN EVIDENCE DEUX EVENEMENTS COMPATIBLES AVEC UN EFFET DE MICROLENTILLE. LA MASSE LA PLUS PROBABLE DES DEFLECTEURS (MAXIMUM DE VRAISEMBLANCE) DANS L'HYPOTHESE D'UN HALO STANDARD EST DE L'ORDRE DE 2 MASSES SOLAIRES. L'EFFET DE CONFUSION STELLAIRE SE REVELE IMPORTANT EN CHAMP ENCOMBRE ET NOUS ETUDIERONS SON IMPACT SUR L'EFFICACITE A L'AIDE D'IMAGES SIMULEES. ENFIN NOUS COMPARERONS LES PREVISIONS DE PLUSIEURS MODELES GALACTIQUES AVEC LES OBSERVATIONS. LA FAIBLE BASE DE TEMPS ET LE MANQUE DE STATISTIQUE RENDENT INDISPENSABLES UNE DEUXIEME ANNEE DE DONNEES, MAIS NOUS SOMMES D'ORES ET DEJA SENSIBLES A DES MASSES DE 0.01 A 1 MASSE SOLAIRE. LA COMPARAISON DES RESULTATS VERS LE LMC ET LE SMC NOUS PERMETTRA PROCHAINEMENT DE CONTRAINDRE LA FORME ET LA NATURE DU HALO DE NOTRE GALAXIE
 
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Alternative Names
Delabrouille Nathalie Palanque-

Nathalie Palanque-Delabrouille cosmóloga francesa

Nathalie Palanque-Delabrouille french cosmologist

PALANQUE DELABROUILLE, NATHALIE

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