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CERN Document Server Sök i 74 journaler efter:  1 - 10nästaslut  gå till journal: Sökningen tog 0.59 sekunder. 
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Towards efficient cosmological predictions for extended cosmology / Lesgourgues, Julien (speaker) (TTK, RWTH Aachen University)
2022 - 4125. TH institutes; New Physics from Galaxy Clustering External links: Talk details; Event details In : New Physics from Galaxy Clustering
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Cosmological probes of neutrino physics / Lesgourgues, Julien (speaker) (TTK, RWTH Aachen University)
Cosmological observations provide constraints on the neutrino sector that are model-dependent, but potentially very strong under a set of reasonable assumptions. I will give an overview of recent cosmological constraints on the neutrino number density, the sum of the neutrino masses and the presence of sterile neutrinos, together with a discussion of the underlying assumptions [...]
2021 - 3456. EuCAPT Virtual Colloquium External link: Event details In : Cosmological probes of neutrino physics
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CMB and Late Universe: Outlook / Lesgourgues, Julien (speaker)
2021 - 1496. Conferences & Workshops; First EuCAPT Annual Symposium External links: Talk details; Event details In : First EuCAPT Annual Symposium
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Time-sliced perturbation theory with primordial non-Gaussianity and effects of large bulk flows on inflationary oscillating features / Vasudevan, Anagha (Bohr Inst.) ; Ivanov, Mikhail M. (New York U., CCPP ; Moscow, INR) ; Sibiryakov, Sergey (Moscow, INR ; EPFL, Lausanne, LPPC ; CERN) ; Lesgourgues, Julien (RWTH Aachen U.)
We extend the formalism of time-sliced perturbation theory (TSPT) for cosmological large-scale structure to include non-Gaussian initial conditions. We show that in such a case the TSPT interaction vertices acquire new contributions whose time-dependence factorizes for the Einstein-de Sitter cosmology. [...]
arXiv:1906.08697; CERN-TH-2019-091; INR-TH-2019-012; TTK-19-22.- 2019-09-19 - 40 p. - Published in : JCAP 1909 (2019) 037 Fulltext: PDF;
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Beyond the traditional Line-of-Sight approach of cosmological angular statistics / Schöneberg, Nils (RWTH Aachen U.) ; Simonović, Marko (Princeton, Inst. Advanced Study ; CERN) ; Lesgourgues, Julien (RWTH Aachen U.) ; Zaldarriaga, Matias (Princeton, Inst. Advanced Study)
We present a new efficient method to compute the angular power spectra of large-scale structure observables that circumvents the numerical integration over Bessel functions, expanding on a recently proposed algorithm based on FFTlog. This new approach has better convergence properties. [...]
arXiv:1807.09540; TTK-18-28; TTK-18-28.- 2018-10-25 - 35 p. - Published in : JCAP 1810 (2018) 047 Fulltext: PDF; External links: 00006 Auto-correlation spectrum of number count (involving only the density source term) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,.; 00002 \textit{(Top)} Auto-correlation spectrum of number count (involving all source contributions) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,. \textit{(Bottom)} Cross-correlation between two redshift bins defined by two Gaussian windows with $(\bar{z}_1, \Delta z_1) = (1.0, 0.05)$ and $(\bar{z}_2, \Delta z_2) = (1.25, 0.05)$.; 00004 Auto-correlation spectrum of cosmic shear (or more precisely of the lensing potential $C_\ell^{\phi \phi}$) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,.; 00012 \textit{(Top)} Auto-correlation spectrum of number count (involving all source contributions) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,. \textit{(Bottom)} Cross-correlation between two redshift bins defined by two Gaussian windows with $(\bar{z}_1, \Delta z_1) = (1.0, 0.05)$ and $(\bar{z}_2, \Delta z_2) = (1.25, 0.05)$.; 00010 Number count spectra involving only density terms for a redshift bin centered at $\bar{z}=1.0$ with width $\Delta z=0.05$\,. \textit{(Top Left)} Total spectra w/o nonlinear corrections from Halofit and massive neutrinos with $M_\nu=1$~eV. \textit{(Top Right)} Impact of these two corrections on the power spectrum, computed as a relative difference (in \%) with respect to the linear spectrum of the massless neutrino model\,. \textit{(Bottom left)} Result of the new method with either the \tquote{full separability} or \tquote{semi-separability} approximations compared to the traditional line-of-sight approach. \textit{(Bottom right)} Relative difference (in \%) between the new and old methods. One can immediately see that the additional effects are well captured and the error remains at the sub-permille level.\\; 00014 \textit{(Top)} Auto-correlation spectrum of number count (involving all source contributions) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,. \textit{(Bottom)} Cross-correlation between two redshift bins defined by two Gaussian windows with $(\bar{z}_1, \Delta z_1) = (1.0, 0.05)$ and $(\bar{z}_2, \Delta z_2) = (1.25, 0.05)$.; 00005 Number count spectra involving only density terms for a redshift bin centered at $\bar{z}=1.0$ with width $\Delta z=0.05$\,. \textit{(Top Left)} Total spectra w/o nonlinear corrections from Halofit and massive neutrinos with $M_\nu=1$~eV. \textit{(Top Right)} Impact of these two corrections on the power spectrum, computed as a relative difference (in \%) with respect to the linear spectrum of the massless neutrino model\,. \textit{(Bottom left)} Result of the new method with either the \tquote{full separability} or \tquote{semi-separability} approximations compared to the traditional line-of-sight approach. \textit{(Bottom right)} Relative difference (in \%) between the new and old methods. One can immediately see that the additional effects are well captured and the error remains at the sub-permille level.\\; 00000 Auto-correlation spectrum of cosmic shear (or more precisely of the lensing potential $C_\ell^{\phi \phi}$) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,.; 00007 Auto-correlation spectrum of number count (involving only the density source term) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,.; 00008 \textit{(Top)} Auto-correlation spectrum of number count (involving all source contributions) in one redshift bin defined by a Gaussian window function with mean redshift $\bar{z}=1.0$ and width $\Delta z = 0.05$\,. \textit{(Bottom)} Cross-correlation between two redshift bins defined by two Gaussian windows with $(\bar{z}_1, \Delta z_1) = (1.0, 0.05)$ and $(\bar{z}_2, \Delta z_2) = (1.25, 0.05)$.; 00001 Number count spectra involving only density terms for a redshift bin centered at $\bar{z}=1.0$ with width $\Delta z=0.05$\,. \textit{(Top Left)} Total spectra w/o nonlinear corrections from Halofit and massive neutrinos with $M_\nu=1$~eV. \textit{(Top Right)} Impact of these two corrections on the power spectrum, computed as a relative difference (in \%) with respect to the linear spectrum of the massless neutrino model\,. \textit{(Bottom left)} Result of the new method with either the \tquote{full separability} or \tquote{semi-separability} approximations compared to the traditional line-of-sight approach. \textit{(Bottom right)} Relative difference (in \%) between the new and old methods. One can immediately see that the additional effects are well captured and the error remains at the sub-permille level.\\; 00009 Number count spectra involving only density terms for a redshift bin centered at $\bar{z}=1.0$ with width $\Delta z=0.05$\,. \textit{(Top Left)} Total spectra w/o nonlinear corrections from Halofit and massive neutrinos with $M_\nu=1$~eV. \textit{(Top Right)} Impact of these two corrections on the power spectrum, computed as a relative difference (in \%) with respect to the linear spectrum of the massless neutrino model\,. \textit{(Bottom left)} Result of the new method with either the \tquote{full separability} or \tquote{semi-separability} approximations compared to the traditional line-of-sight approach. \textit{(Bottom right)} Relative difference (in \%) between the new and old methods. One can immediately see that the additional effects are well captured and the error remains at the sub-permille level.\\; 00003 Another consequence of the Limber limit: For large $\ell$ the $t_{min}$ parameter behaves as $1/\ell$ (left), and the $|I_\ell(\nu,1)/\ell^{\nu-2}|$ is constant as in equation \ref{eq_Il_limit} (right). Note that the oscillations due to imaginary $\nu$ are correctly captured and the relative size approaches the correct constant. The black lines indicate the behavior for $\nu=-2.1+30i$ and $\epsilon=10^{-4}$, while the grey lines specify asymptotes. On the left, the grey line is $\ell^{-1}$ times an arbitrary constant (here $30/\ell$), while on the right side the constant is fixed by \ref{eq_Il_limit}. The constant for $t_{min}$ is not exactly $\log(1/\epsilon)$ because of the influence of the hypergeometric function.; 00011 An illustration of the Limber limit: For large $\ell$ the area under the curve $I_\ell(\nu,t)$ approaches $\pi^2 \ell^{\nu-3}$ when integrated from $0$ to $1$. We see that the factor $\ell^{3-\nu} \, I_\ell(\nu,t)$ approaches the constant $\pi^2$, which is an equivalent statement.; 00013 Another consequence of the Limber limit: For large $\ell$ the $t_{min}$ parameter behaves as $1/\ell$ (left), and the $|I_\ell(\nu,1)/\ell^{\nu-2}|$ is constant as in equation \ref{eq_Il_limit} (right). Note that the oscillations due to imaginary $\nu$ are correctly captured and the relative size approaches the correct constant. The black lines indicate the behavior for $\nu=-2.1+30i$ and $\epsilon=10^{-4}$, while the grey lines specify asymptotes. On the left, the grey line is $\ell^{-1}$ times an arbitrary constant (here $30/\ell$), while on the right side the constant is fixed by \ref{eq_Il_limit}. The constant for $t_{min}$ is not exactly $\log(1/\epsilon)$ because of the influence of the hypergeometric function.
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6.
Exploring Cosmic Origins with CORE: Inflation / Finelli, Fabio (Bologna Observ. ; INFN, Bologna) ; Bucher, Martin (APC, Paris) ; Achúcarro, Ana (Leiden U. ; Basque U., Bilbao) ; Ballardini, Mario (Bologna U. ; Bologna Observ. ; INFN, Bologna) ; Bartolo, Nicola (Padua U. ; INFN, Padua ; Padua Observ.) ; Baumann, Daniel (Cambridge U., DAMTP ; Amsterdam U.) ; Clesse, Sébastien (Aachen, Tech. Hochsch.) ; Errard, Josquin (ILP, Paris ; Paris U., VI-VII) ; Handley, Will (Cambridge U. ; Cambridge U., KICC) ; Hindmarsh, Mark (Sussex U. ; Helsinki Inst. of Phys. ; Helsinki U.) et al. /CORE
We forecast the scientific capabilities to improve our understanding of cosmic inflation of CORE, a proposed CMB space satellite submitted in response to the ESA fifth call for a medium-size mission opportunity. The CORE satellite will map the CMB anisotropies in temperature and polarization in 19 frequency channels spanning the range 60-600 GHz. [...]
arXiv:1612.08270.- 2018-04-05 - 100 p. - Published in : JCAP 04 (2018) 016 Fulltext: PDF;
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Neutrino physics (20'+10) / Lesgourgues, Julien (speaker) (Institute for Theoretical Particle Physics and Cosmology Aachen University)
2016 - 1709. Seminars/Workshops; Towards a next space probe for CMB observations and cosmic origins exploration External links: Talk details; Event details In : Towards a next space probe for CMB observations and cosmic origins exploration
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Neutrino masses and cosmology with Lyman-alpha forest power spectrum / Palanque-Delabrouille, Nathalie (IRFU, SPP, Saclay) ; Yèche, Christophe (IRFU, SPP, Saclay) ; Baur, Julien (IRFU, SPP, Saclay) ; Magneville, Christophe (IRFU, SPP, Saclay) ; Rossi, Graziano (Sejong U.) ; Lesgourgues, Julien (ITPP, Lausanne ; CERN ; Annecy, LAPTH) ; Borde, Arnaud (IRFU, SPP, Saclay ; Thomson-CSF, Bagneux) ; Burtin, Etienne (IRFU, SPP, Saclay) ; LeGoff, Jean-Marc (IRFU, SPP, Saclay) ; Rich, James (IRFU, SPP, Saclay) et al.
We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the $\Lambda$CDM model, using the one-dimensional Ly$\alpha$-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. [...]
arXiv:1506.05976.- 2015-11-06 - 23 p. - Published in : JCAP 11 (2015) 011 Fulltext: PDF; Preprint: PDF; External link: Preprint
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Constraints on dark radiation from cosmological probes / Rossi, Graziano (Sejong U.) ; Yèche, Christophe (IRFU, SPP, Saclay) ; Palanque-Delabrouille, Nathalie (IRFU, SPP, Saclay) ; Lesgourgues, Julien (CERN ; Annecy, LAPTH)
We present joint constraints on the number of effective neutrino species N_eff and the sum of neutrino masses M_nu, based on a technique which exploits the full information contained in the one-dimensional Lyman-Alpha forest flux power spectrum, complemented by additional cosmological probes. In particular, we obtain N_eff=2.91(+0.21)(-0.22) (95% CL) and M_nu<0.15 eV (95% CL) when we combine BOSS Lyman-Alpha forest data with CMB (Planck+ACT+SPT+WMAP polarization) measurements, and N_eff=2.88(+0.20)(-0.20) (95% CL) and M_nu<0.14 eV (95% CL) when we further add baryon acoustic oscillations. [...]
arXiv:1412.6763; CERN-PH-TH-2014-267; CERN-PH-TH-2014-267.- 2015-09-08 - 13 p. - Published in : Phys. Rev. D 92 (2015) 063505 APS Open Access article: PDF; Fulltext: PDF; External link: Preprint
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10.
Robustness of cosmic neutrino background detection in the cosmic microwave background / Audren, Benjamin (IPT, Lausanne) ; Bellini, Emilio (ICC, Barcelona U.) ; Cuesta, Antonio J (ICC, Barcelona U.) ; Gontcho, Satya Gontcho A (ICC, Barcelona U.) ; Lesgourgues, Julien (CERN ; Annecy, LAPTH) ; Niro, Viviana (Madrid, Autonoma U ; Madrid, IFT) ; Pellejero-Ibanez, Marcos (IAC, La Laguna ; Laguna U., Tenerife) ; Pérez-Ràfols, Ignasi (ICC, Barcelona U.) ; Poulin, Vivian (Annecy, LAPTH) ; Tram, Thomas et al.
The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. [...]
arXiv:1412.5948; CERN-PH-TH-2014-266; LAPTH-238-14; FTUAM-14-51; IFT-UAM-CSIC-14-132.- 2015 - 18 p. - Published in : JCAP 03 (2015) 036 Fulltext: PDF; External link: Preprint
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