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Lasenby, A.; Page, L.; Vega, H.J. de; Biermann, P.L.; Ma, E.; Laveder, M.; Kormendy, J.; Weinheimer, C.; Freeman, K.; Walker, M.; Conselice, C.J.; Rebolo, R.; Wehus, K.; Mirabel, F.; Serenelli, A.; Das, S.; Cooray, A.; Burigana, C.; Sanchez, N.G.; Mather, J.C.; Smoot, G.F.; Schmidt, B.P.; Tognini, M.A.
Ecole Internationale Daniel Chalonge, Paris (France)2014
Ecole Internationale Daniel Chalonge, Paris (France)2014
AbstractAbstract
[en] Recently, Warm (keV scale) Dark Matter emerged impressively over CDM (Cold Dark Matter) as the leading Dark Matter candidate. In the context of this new Dark Matter situation, which implies novelties in the astrophysical, cosmological and keV particle physics context, this 16. Paris Colloquium 2012 is devoted to the LambdaWDM Standard Model of the Universe. The topics of the colloquium are as follows: -) observational and theoretical progress on the nature of dark matter: keV scale warm dark matter, -) large and small scale structure formation in agreement with observations at large scales and small galactic scales, and -) neutrinos in astrophysics and cosmology. This document gathers the slides of the presentations.
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2014; 1301 p; 16. Paris Cosmology Colloquium 2012 - The new standard model of the universe: Lambda Warm Dark Matter (LWDM) - Theory and observations; Paris (France); 25-27 Jul 2012; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/INIS/contacts/
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Miscellaneous
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[en] In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations
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Carpathian Summer School of Physics 2014; Sinaia (Romania); 13-26 Jul 2014; (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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AbstractAbstract
[en] The Rastall’s theory is a modification of General Relativity touching one of the cornestone of gravity theory: the conservation laws. In Rastall’s theory, the energy-momentum tensor is not conserved anymore, depending now on the gradient of the Ricci curvature. In this sense, this theory can be seen as a classical implementation of quantum effects in a curved background space-time. We exploit this structure in order to reproduce some results of an effective theory of quantum loop cosmology. Later, we propose a model for the dark sector of the universe. In this case, the corresponding ΛCDM model appears as the only model consistent with observational data
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Conference on Cosmology and Gravitation in the Southern Cone; Valparaiso (Chile); 27-31 May 2013; (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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AbstractAbstract
[en] In order to treat quantum cosmology in the framework of Weyl spacetimes we take the first step of extending the Arnowitt-Deser-Misner formalism to Weyl geometry. We then obtain an expression of the curvature tensor in terms of spatial quantities by splitting spacetime in (3+l)-dimensional form. We next write the Lagrangian of the gravitation field based in Weyl-type gravity theory. We extend the general relativistic formalism in such a way that it can be applied to investigate the quantum cosmology of models whose spacetimes are endowed with a Weyl geometrical structure
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Conference on Cosmology and Gravitation in the Southern Cone; Valparaiso (Chile); 27-31 May 2013; (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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Garbarz, Alan; Giribet, Gaston; Goya, Andrés; Leston, Mauricio, E-mail: alan-at@df.uba.ar, E-mail: gaston-at@df.uba.ar, E-mail: af.goya-at@df.uba.ar, E-mail: gaston-at@df.uba.ar, E-mail: af.goya-at@df.uba.ar, E-mail: mauricio-at@iafe.uba.ar2015
AbstractAbstract
[en] We consider critical gravity in three dimensions; that is, the New Massive Gravity theory formulated about Anti-de Sitter (AdS) space with the specific value of the graviton mass for which it results dual to a two-dimensional conformai field theory with vanishing central charge. As it happens with Kerr black holes in four-dimensional critical gravity, in three-dimensional critical gravity the Bañados-Teitelboim-Zanelli black holes have vanishing mass and vanishing angular momentum. However, provided suitable asymptotic conditions are chosen, the theory may also admit solutions carrying non-vanishing charges. Here, we give simple examples of exact solutions that exhibit falling-off conditions that are even weaker than those of the so-called Log-gravity. For such solutions, we define the quasilocal stress-tensor and use it to compute conserved charges. Despite the drastic deformation of AdS3 asymptotic, these solutions have finite mass and angular momentum, which are shown to be non-zero
Primary Subject
Source
Conference on Cosmology and Gravitation in the Southern Cone; Valparaiso (Chile); 27-31 May 2013; (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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AbstractAbstract
[en] We review a relationship between cosmological vacuum energy and massive gravitons as given by Garattini and also the nonlinear electrodynamics of Camara et.al (2004) for a non singular universe and NLED. . In evaluating the Garattini result, we find that having the scale factor close to zero due to a given magnetic field value in, an early universe magnetic field affects how we would interpret Garattini’s linkage of the ‘cosmological constant’ value and non zero graviton mass.. We close as to how these initial conditions affect the issue of an early universe initial pressure and its experimental similarities and differences with results by Corda and Questa as to negative pressure at the surface of a star. Note, that in theDupays et.al. article , the star in question is rapidly spinning, which is not. assumed in the Camara et.al article , for an early universe. Also, Corda and Questa do not assume a spinning star. We conclude with a comparison between the Lagrangian Dupays and other authors bring up for non linear electrodynamics which is for rapidly spinning neutron stars , and a linkage between the Goldstone theorem and NLED. Our conclusion is for generalizing results seen in the Dupays neutron star Lagrangian with conditions which may confirm C. A. Escobar and L. F. Urrutia’s work on the Goldstone theorem and non linear electrodynamics, for some future projects we have in mind. If the universe does not spin, then we will stick with the density analogy given by adapting density as proportional to one over the fourth power of the minimum value of the scale factor as computed by adaptation of the Camara et.al.(2004) theory for non spinning universes. What may happen is that the Camara (2004) density and Quintessential density are both simultaneously satisfied, which would put additional restrictions on the magnetic field, which is one of our considerations, regardless if a universe spins, akin to spinning neutron stars. The spinning universe though may allow for easier reconciliation of the ‘Goldstone’ behavior of gravity and NLED though
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ICNAAM-2014: International Conference on Numerical Analysis and Applied Mathematics 2014; Rhodes (Greece); 22-28 Sep 2014; (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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AbstractAbstract
[en] Carrying 1044 joules of kinetic energy and a rich mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale) down to femtometer-scale nuclear reactions. We will discuss our emerging understanding of the convectively-unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed
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(c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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Haider, M.J.
University of Innsbruck (Austria)2013
University of Innsbruck (Austria)2013
AbstractAbstract
[en] In this thesis work on building a state of the art galaxy cluster simulation framework is presented. To compute the dark matter structure of the galaxy cluster, zoomed initial conditions and the n-body code Gadget2 are used. A galaxy catalogue is created applying the Galacticus semi-analytical model on the merger-tree extracted from the n-body simulation. The hydrodynamics of the intra-cluster medium is simulated using the FLASH code. Besides the new simulation framework an analysis about the enrichment history of the intra-cluster medium has been performed, where the metallicity at redshift zero has been decomposed into several enrichment epochs. Furthermore, a method to study the fluctuations in the intra-cluster medium using Fourier techniques has been developed. Using this method on a simulated galaxy cluster, it is shown that the spectral density of the fluctuations in the intra-cluster medium follows a power law. (author)
[de]
In dieser Arbeit wird ein modernes Framework für die Simulation von Galaxienhaufen präsentiert. Um die Struktur der Dunklen Materie eines Galaxienhaufens zu berechnen, werden der N-Teilchen-Code Gadget2 und spezielle Anfangsbedingungen verwendet, welche es erlauben einen Galaxienhaufen in einer kosmologischen Box mit hoher Auflösung zu simulieren (Zoomed Initial Conditions). Um aus der Verteilung der Dunklen Materie einen Galaxienkatalog zu erstellen, wird das semi-analytische Galaxienentstehungsmodell Galacticus angewandt. Die Dynamik des Haufengases wird mit dem Hydrodynamikcode FLASH berechnet. Außerdem wurde eine Analyse der Anreicherungsgeschichte des Haufengases durchgeführt, wofür die Metallizität bei einer Rotverschiebung von Null in verschiedene Anreicherungsepochen aufgespalten wurde. Weiters wurde eine Methode entwickelt, um unter Benützung von Fourier-Techniken die Fluktuationen im Haufengas zu analysieren. Die Anwendung dieser Methode auf einen simulierten Galaxienhaufen zeigt, dass die spektrale Leistungsdichte der Fluktuationen einem Potenzgesetz gehorcht. (author)Primary Subject
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2013; 111 p; Available from Library of the University of Innsbruck, Innrain 50, 6020 Innsbruck (Austria); authors keywords: astrophysics / astronomy / galaxy clusters / hydrodynamics / simulation / dark matter / galaxies; Thesis (Ph.D.)
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Seljebotn, D. S.; Eriksen, H. K.; Bull, P.; Mardal, K.-A.; Jewell, J. B., E-mail: d.s.seljebotn@astro.uio.no2014
AbstractAbstract
[en] We present a multi-level solver for drawing constrained Gaussian realizations or finding the maximum likelihood estimate of the cosmic microwave background sky, given noisy sky maps with partial sky coverage. The method converges substantially faster than existing Conjugate Gradient (CG) methods for the same problem. For instance, for the 143 GHz Planck frequency channel, only three multi-level W-cycles result in an absolute error smaller than 1 μK in any pixel. Using 16 CPU cores, this translates to a computational expense of 6 minutes wall time per realization, plus 8 minutes wall time for a power-spectrum-dependent precomputation. Each additional W-cycle reduces the error by more than an order of magnitude, at an additional computational cost of 2 minutes. For comparison, we have never been able to achieve similar absolute convergence with conventional CG methods for this high signal-to-noise data set, even after thousands of CG iterations and employing expensive preconditioners. The solver is part of the Commander 2 code, which is available with an open source license at http://commander.bitbucket.org/
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Available from http://dx.doi.org/10.1088/0067-0049/210/2/24; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Rowe, Jason F.; Bryson, Stephen T.; Howell, Steve B.; Batalha, Natalie M.; Huber, Daniel; Jenkins, Jon M.; Latham, David W.; Buchhave, Lars A.; Gautier, Thomas N. III; Rogers, Leslie; Ciardi, David; Fischer, Debra A.; Basu, Sarbani; Gilliland, Ronald L.; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Chaplin, William J.2014
AbstractAbstract
[en] We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm–3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ∼2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O)
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Available from http://dx.doi.org/10.1088/0067-0049/210/2/20; Country of input: International Atomic Energy Agency (IAEA)
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