1,653 research outputs found
Neutrino masses and cosmology with Lyman-alpha forest power spectrum
No full textWe present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the CDM model, using the one-dimensional Ly-forest power spectrum measured by Palanque-Delabrouille et al. (2013) from SDSS-III/BOSS, complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by Palanque-Delabrouille et al. (2015) by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Ly data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index . Combining BOSS Ly with Planck CMB constrains the sum of neutrino masses to eV (95\% C.L.) including all identified systematic uncertainties, tighter than our previous limit (0.15 eV) and more robust. Adding Ly data to CMB data reduces the uncertainties on the optical depth to reionization , through the correlation of with . Similarly, correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations . The tension on can be accommodated by allowing for a running . Allowing running as a free parameter in the fits does not change the limit on . We discuss possible interpretations of these results in the context of slow-roll inflation.We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the ΛCDM model, using the one-dimensional Lyα-forest power spectrum measured by [1] from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III), complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by [2] by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Lyα data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index ns. Combining BOSS Lyα with Planck CMB constrains the sum of neutrino masses to ∑ m(ν) < 0.12 eV (95% C.L.) including all identified systematic uncertainties, tighter than our previous limit (0.15 eV) and more robust. Adding Lyα data to CMB data reduces the uncertainties on the optical depth to reionization τ, through the correlation of τ with σ(8). Similarly, correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations r. The tension on ns can be accommodated by allowing for a running dns/d ln k. Allowing running as a free parameter in the fits does not change the limit on ∑ m(ν). We discuss possible interpretations of these results in the context of slow-roll inflation.We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the CDM model, using the one-dimensional Ly-forest power spectrum measured by Palanque-Delabrouille et al. (2013) from SDSS-III/BOSS, complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by Palanque-Delabrouille et al. (2015) by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Ly data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index . Combining BOSS Ly with Planck CMB constrains the sum of neutrino masses to eV (95\% C.L.) including all identified systematic uncertainties, tighter than our previous limit (0.15 eV) and more robust. Adding Ly data to CMB data reduces the uncertainties on the optical depth to reionization , through the correlation of with . Similarly, correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations . The tension on can be accommodated by allowing for a running . Allowing running as a free parameter in the fits does not change the limit on . We discuss possible interpretations of these results in the context of slow-roll inflation
Lyman-alpha forests cool warm dark matter
No full textThe free-streaming of keV-scale particles impacts structure growth on scales that are probed by the Lyman-alpha forest of distant quasars. Using an unprecedentedly large sample of medium-resolution QSO spectra from the ninth data release of SDSS, along with a state-of-the-art set of hydrodynamical simulations to model the Lyman-alpha forest in the non-linear regime, we issue one of the tightest bounds to date, from Ly-alpha data alone, on pure dark matter particles: mX > 4.09 keV (95% CL) for early decoupled thermal relics such as a hypothetical gravitino, and correspondingly m(s) > 24.4 keV (95% CL) for a non-resonantly produced right-handed neutrino. This limit depends on the value on n(s), and Planck measures a higher value of ns than SDSS-III/BOSS. Our bounds thus change slightly when Ly-alpha data are combined with CMB data from Planck 2016. The limits shift to mX > 2.96 keV (95% CL) and m(s) > 16.0 keV (95% CL). Thanks to SDSS-III data featuring smaller uncertainties and covering a larger redshift range than SDSS-I data, our bounds confirm the most stringent results established by previous works and are further at odds with a purely non-resonantly produced sterile neutrino as dark matter
Extragalactic sources in Cosmic Microwave Background maps
No full textASI/INAF [2014-024-R.0]; National Aeronautics and Space Administration; South African National Research Foundation (NRF); Polish National Science Centre [UMO-2012/07/D/ST9/02785]De Zotti, G., Castex, G., González-Nuevo, J., Lopez-Caniego, M., Negrello, M., Cai, Z.-Y., Clemens, M., Delabrouille, J., Herranz, D., Bonavera, L., Melin, J.-B., Tucci, M., Serjeant, S., Bilicki, M., Andreani, P., Clements, D.L., Toffolatti, L., Roukema, B.F
New approach for precise computation of Lyman-alpha forest power spectrum with hydrodynamical simulations
No full textCurrent experiments are providing measurements of the flux power spectrum from the Lyman-α forests observed in quasar spectra with unprecedented accuracy. Their interpretation in terms of cosmological constraints requires specific simulations of at least equivalent precision. In this paper, we present a suite of cosmological N-body simulations with cold dark matter and baryons, specifically aiming at modeling the low-density regions of the inter-galactic medium as probed by the Lyman-α forests at high redshift. The simulations were run using the GADGET-3 code and were designed to match the requirements imposed by the quality of the current SDSS-III/BOSS or forthcoming SDSS-IV/eBOSS data. They are made using either 2 × 7683 1 billion or 2 × 1923 14 million particles, spanning volumes ranging from (25 Mpc h−1)3 for high-resolution simulations to (100 Mpc h−1)3 for large-volume ones. Using a splicing technique, the resolution is further enhanced to reach the equivalent of simulations with 2 × 30723 58 billion particles in a (100 Mpc h−1)3 box size, i.e. a mean mass per gas particle of 1.2 × 105M⊙ h−1. 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 four cosmological parameters (ns, σ8, Ωm and H0) and two astrophysical parameters (T0 and γ) that are related to the heating rate of the intergalactic medium. 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 six 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. Finally, a comparison to the one-dimensional Lyman-α forest power spectrum obtained with BOSS by [1] shows an excellent agreement
Exploring cosmic origins with CORE: Survey requirements and mission design
No full textThe CORE collaboration thanks CNES, Thales Alenia Space, and Air Liquide Advanced Technologies for advice and technical support during the preparation of the CORE proposal. We also thank the ESA CDF team for the CMB Polarisation CDF study performed in March 2016, the results of which were extensively used to define the mission concept presented in this paper. J.G.N. acknowledges financial support from the Spanish MINECO for a Ramon y Cajal fellowship (RYC-2013-13256) and the I+D 2015 project AYA2015-65887-P (MINECO/FEDER). CJM is supported by an FCT Research Professorship, contract reference IF/00064/2012, funded by FCT/MCTES (Portugal) and POPH/FSE. F.J.C., R.F.-C., E.M.-G. and P.V. acknowledge support from the Spanish Ministerio de Econom´ıa y Competitividad project ESP2015-70646-C2-1-R (cofinanced with EU FEDER funds), ConsoliderIngenio 2010 project CSD2010-00064 and from the CSIC “Proyecto Intramural Especial” project 201550E091. FA is supported by the National Taiwan University (NTU) under Project No. 103R4000 and by the NTU Leung Center for Cosmology and Particle Astrophysics (LeCosPA) under Project No. FI121. BFR acknowledges support from the National Science Centre, Poland, under grant 2014/13/B/ST9/00845.Macìas-Pérez, J.F., Delabrouille, J., De Bernardis, P., Bouchet, F.R., Achúcarro, A., Ade, P.A.R., Allison, R., Arroja, F., Artal, E., Ashdown, M., Baccigalupi, C., Ballardini, M., Banday, A.J., Banerji, R., Barbosa, D., Bartlett, J., Bartolo, N., Basak, S., Baselmans, J.J.A., Basu, K., Battistelli, E.S., Battye, R., Baumann, D., Benoít, A., Bersanelli, M., Bideaud, A., Biesiada, M., Bilicki, M., Bonaldi, A., Bonato, M., Borrill, J., Boulanger, F., Brinckmann, T., Brown, M.L., Bucher, M., Burigana, C., Buzzelli, A., Cabass, G., Cai, Z.-Y., Calvo, M., Caputo, A., Carvalho, C.-S., Casas, F.J., Castellano, G., Catalano, A., Challinor, A., Charles, I., Chluba, J., Clements, D.L., Clesse, S., Colafrancesco, S., Colantoni, I., Contreras, D., Coppolecchia, A., Crook, M., D'Alessandro, G., D'Amico, G., Silva, A.D., De Avillez, M., De Gasperis, G., Petris, M.D., De Zotti, G., Danese, L., Désert, F.-X., Desjacques, V., Valentino, E.D., Dickinson, C., Diego, J.M., Doyle, S., Durrer, R., Dvorkin, C., Eriksen, H.K., Errard, J., Feeney, S., Fernández-Cobos, R., Finelli, F., Forastieri, F., Franceschet, C., Fuskeland, U., Galli, S., Génova-Santos, R.T., Gerbino, M., Giusarma, E., Gomez, A., González-Nuevo, J., Grandis, S., Greenslade, J., Goupy, J., Hagstotz, S., Hanany, S., Handley, W., Henrot-Versillé, S., Hernández-Monteagudo, C., Hervias-Caimapo, C., Hills, M., Hindmarsh, M., Hivon, E., Hoang, D.T., Hooper, D.C., Hu, B., Keihänen, E., Keskitalo, R., Kiiveri, K., Kisner, T., Kitching, T., Kunz, M., Kurki-Suonio, H., Lagache, G., Lamagna, L., Lapi, A., Lasenby, A., Lattanzi, M., Brun, A.M.C.L., Lesgourgues, J., Liguori, M., Lindholm, V., Lizarraga, J., Luzzi, G., Macìas-Pérez, J.F., Maffei, B., Mandolesi, N., Martin, S., Martinez-Gonzalez, E., Martins, C.J.A.P., Masi, S., Massardi, M., Matarrese, S., Mazzotta, P., McCarthy, D., Melchiorri, A., Melin, J.-B., Mennella, A., Mohr, J., Molinari, D., Monfardini, A., Montier, L., Natoli, P., Negrello, M., Notari, A., Noviello, F., Oppizzi, F., O'Sullivan, C., Pagano, L., Paiella, A., Pajer, E., Paoletti, D., Paradiso, S., Partridge, R.B., Patanchon, G., Patil, S.P., Perdereau, O., Piacentini, F., Piat, M., Pisano, G., Polastri, L., Polenta, G., Pollo, A., Ponthieu, N., Poulin, V., Prêle, D., Quartin, M., Ravenni, A., Remazeilles, M., Renzi, A., Ringeval, C., Roest, D., Roman, M., Roukema, B.F., Rubiño-Martin, J.-A., Salvati, L., Scott, D., Serjeant, S., Signorelli, G., Starobinsky, A.A., Sunyaev, R., Tan, C.Y., Tartari, A., Tasinato, G., Toffolatti, L., Tomasi, M., Torrado, J., Tramonte, D., Trappe, N., Triqueneaux, S., Tristram, M., Trombetti, T., Tucci, M., Tucker, C., Urrestilla, J., Väliviita, J., De Weygaert, R.V., Tent, B.V., Vennin, V., Verde, L., Vermeulen, G., Vielva, P., Vittorio, N., Voisin, F., Wallis, C., Wandelt, B., Wehus, I.K., Weller, J., Young, K., Zannoni, M
Issues and methods for CMB anisotropy data reduction
No full textMajor issues and existing methods for the reduction of CMB anisotropy data are reviewed. An emphasis is put on the proper modelling of the data. It is suggested that the robustness of methods could be improved by taking into account the uncertainty of the model for finding optimal solutions
A needlet internal linear combination analysis of WMAP 7-year data: estimation of CMB temperature map and power spectrum
No full textThe Wilkinson Microwave Anisotropy Probe (WMAP) satellite has provided high-resolution, high signal-to-noise ratio maps of the sky in five main frequency bands ranging from 23 to 94 GHz. These maps consist in noisy observations, a mixture of cosmic microwave background (CMB) anisotropies and of other astrophysical foreground emissions. We present a new foreground-cleaned CMB map, as well as a new estimation of the angular power spectrum of CMB temperature anisotropies, based on 7 years of observations of the sky by WMAP. The method used to extract the CMB signal is based on an implementation of minimum variance linear combination of WMAP channels and of external full-sky foreground maps on a frame of spherical wavelets called needlets. The use of spherical needlets makes possible localized filtering both in pixel space and harmonic space, so that the internal linear combination (ILC) weights are adjusted as a function of location on the sky and of angular scale. Our CMB power spectrum estimate is computed using cross-power spectra between CMB maps obtained from different individual years of observation. The CMB power spectrum is corrected for low-level biases originating from the ILC method and foreground residual emissions, by making use of realistic simulations of the whole analysis pipeline. Our error bars, compatible with those obtained by the WMAP collaboration, are obtained from the combination of two terms: the internal scatter of individual Cℓ in each ℓ bin, and a term originating from uncertainties in our correction for biases due to empirical correlations between CMB and foregrounds, as well as to residual foregrounds in the CMB maps. Our power spectrum is essentially compatible, within error bars, with the result obtained by the WMAP collaboration, although it is systematically lower at the lowest multipoles, more than expected considering that the two estimates are based on the same original data. Exhaustive investigations of the presence of a possible bias in our estimate fail to explain the difference. Comparison with several other analyses confirms the existence of differences in the large-scale CMB power, which are significant enough that until the origin of this discrepancy is understood, some caution is recommended in scientific work relying much on the exact value of the CMB power spectrum in the Sachs-Wolfe plateau
Measuring CMB polarisation with the Planck mission
No full textIn this paper, we discuss why and how the Planck mission, originally designed and proposed for mapping CMB intensity fluctuations, has been revised for polarisation measurement capability as well
The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths
No full textJ. Delabrouille et al.We present the Planck Sky Model (PSM), a parametric model for generating all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H ii regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modelling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared background. The PSM enables the production of random realisations of the sky emission, constrained to match observational data within their uncertainties. It is implemented in a software package that is regularly updated with incoming information from observations. The model is expected to serve as a useful tool for optimising planned microwave and sub-millimetre surveys and testing data processing and analysis pipelines. It is, in particular, used to develop and validate data analysis pipelines within the Planck collaboration. A version of the software that can be used for simulating the observations for a variety of experiments is made available on a dedicated website. © 2013 ESO.SB has been supported by a postdoctoral grant from the “Physique des deux Infinis” (P2I) Consortium. CD acknowledges an STFC Advanced Fellowship and an ERC IRG grant under the FP7.Peer Reviewe
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