Date: Wed, 30 Mar 11 00:06:22 GMT Subject: gr-qc daily 5 new + 7 crosses received by eprepget ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ Send any comments regarding submissions directly to submitter. ------------------------------------------------------------------------------ Archives at http://arxiv.org/ To unsubscribe, e-mail To: gr-qc@arXiv.org, Subject: cancel ------------------------------------------------------------------------------ received by eprepget from Mon 28 Mar 11 20:00:00 GMT to Tue 29 Mar 11 20:00:00 GMT ------------------------------------------------------------------------------ \\ arXiv:1103.5465 Date: Mon, 28 Mar 2011 20:00:06 GMT (84kb) Title: Measuring the dark matter equation of state Authors: Ana Laura Serra and Mariano Javier de Le\'on Dom\'inguez Romero Categories: gr-qc astro-ph.CO Comments: 4 pages, 2 figures, submitted to MNRAS Letters \\ The nature of the dominant component of galaxies and clusters remains unknown. While the astrophysics comunity supports the cold dark matter (CDM) paradigm as a clue factor in the current cosmological model, no direct CDM detections have been performed. Faber and Visser 2006 have suggested a simple method for measuring the dark matter equation of state. By combining kinematical and gravitational lensing data it is possible to test the widely adopted assumption of pressureless dark matter. According to this formalism, we have measured the dark matter equation of state for first time using improved techniques. We have found that the value of the equation of state parameter is consistent with pressureless dark matter within the errors. Nevertheless the measured value is lower than expected. This fact follows from the well known differences between the masses determinated by lensing and kinematical methods. We have tested our techniques using simulations and we have also analyzed possible sources of errors that could invalidate or mimic our results. In the light of this result, we can now suggest that the understanding of the nature of dark matter is incomplete unless a complete general relativistic analysis is used. \\ ( http://arxiv.org/abs/1103.5465 , 84kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5543 Date: Tue, 29 Mar 2011 05:00:20 GMT (680kb) Title: Quantum Scalar-metric Cosmology with Chaplygin gas Authors: Barun Majumder Categories: gr-qc astro-ph.CO Comments: 13 pages, 6 figures Journal-ref: Physics Letters B Phys. Lett. B, Volume 697, Issue 2, Pages 101-106, 2011 DOI: 10.1016/j.physletb.2011.01.054 \\ A spatially flat Friedmann-Robertson-Walker(FRW) cosmological model with generalized Chaplygin gas is studied in the context of scalar-metric formulation of cosmology. Schutz's mechanism for the perfect fluid is applied with generalized Chaplygin gas and the classical and quantum dynamics for this model is studied. It is found that the only surviving matter degree of freedom played the role of cosmic time. For the quantum mechanical description it is possible to find the wave packet which resulted from the linear superposition of the wave functions of the Schr\"{o}dinger-Wheeler-DeWitt(SWD) equation, which is a consequence of the above formalism. The wave packets show two distinct dominant peaks and propagate in the direction of increasing scale factor. It may happen that our present universe originated from one of those peaks. The many-world and ontological interpretation of quantum mechanics is applied to investigate about the behaviour of the scale factor and the scalar field(considered for this model). In both the cases the scale factor avoids singularity and a bouncing non-singular universe is found. \\ ( http://arxiv.org/abs/1103.5543 , 680kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5612 Date: Tue, 29 Mar 2011 12:00:19 GMT (814kb,D) Title: Geodesic deviations: modeling extreme mass-ratio systems and their gravitational waves Authors: G. Koekoek, J.W. van Holten Categories: gr-qc \\ The method of geodesic deviations has been applied to derive accurate analytic approximations to geodesics in Schwarzschild space-time. The results are used to construct analytic expressions for the source terms in the Regge-Wheeler and Zerilli-Moncrief equations, which describe the propagation of gravitational waves emitted by a compact massive object moving in the Schwarzschild background space-time. The wave equations are solved numerically to provide the asymptotic form of the wave at large distances for a series of non-circular bound orbits with periastron distances up to the ISCO radius, and the power emitted in gravitational waves by the extreme-mass ratio binary system is computed. The results compare well with those of purely numerical approaches. \\ ( http://arxiv.org/abs/1103.5612 , 814kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5646 Date: Tue, 29 Mar 2011 14:07:35 GMT (12kb) Title: 2+1 dimensional magnetically charged solutions in Einstein - Power - Maxwell theory Authors: S. Habib Mazharimousavi, O. Gurtug, M. Halilsoy and O. Unver Categories: gr-qc Comments: 10 pages, no figure \\ We obtain a class of magnetically charged solutions in 2+1 dimensional Einstein - Power - Maxwell theory. In the linear Maxwell limit such horizonless solutions are known to exist. We show that in 3D geometry, black hole solutions with magnetic charge does not exist even if it is sourced by power Maxwell field. Physical properties of the solution with particular power k of the Maxwell field is investigated. The true timelike naked curvature singularity develops when k>1/2. For specific power parameter k, the occurrence of timelike naked singularity is analysed in quantum mechanical point of view. Quantum test particles obeying the Klein - Gordon and the Dirac equations are used to probe the singularity. In general, the spacetime remains quantum mechanically singular for particles obeying the Klein - Gordon and Dirac equations. However, for certain finely tuned wave modes obeying the Klein - Gordon and Dirac equations, the spacetime can be quantum regular. \\ ( http://arxiv.org/abs/1103.5646 , 12kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5731 Date: Tue, 29 Mar 2011 19:10:22 GMT (8kb) Title: Bose-Einstein Condensate Dark Matter Phase Transition from U(1) Symmetry Breaking Authors: Tonatiuh Matos and Abril Su\'arez-Ram\irez Categories: gr-qc cond-mat.other hep-th Comments: 4 pages \\ Starting with a scalar field in a thermal bath using the one loop quantum corrections potential, we rewrite the Klein-Gordon equation in its thermodynamical representation and study the phase transition of this scalar field due to the U(1) symmetry breaking. We find the corresponding thermodynamic and viscosity expressions, and propose that this terms can be measured in the laboratory in order to know if the phase transition of a Bose-Einstein Condensate can be explained in terms of quantum field theory in a simple and elegant way. \\ ( http://arxiv.org/abs/1103.5731 , 8kb) %-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%- ------------------------------------------------------------------------------ \\ arXiv:1103.5468 (*cross-listing*) Date: Mon, 28 Mar 2011 20:03:24 GMT (71kb,D) Title: Generalised massive gravity one-loop partition function and AdS/(L)CFT Authors: Mario Bertin, Daniel Grumiller, Dmitri Vassilevich and Thomas Zojer Categories: hep-th gr-qc Comments: 25 p., 2 jpg figs \\ The graviton 1-loop partition function is calculated for Euclidean generalised massive gravity (GMG) using AdS heat kernel techniques. We find that the results fit perfectly into the AdS/(L)CFT picture. Conformal Chern-Simons gravity, a singular limit of GMG, leads to an additional contribution in the 1-loop determinant from the conformal ghost. We show that this contribution has a nice interpretation on the conformal field theory side in terms of a semi-classical null vector at level two descending from a primary with conformal weights (3/2,-1/2). \\ ( http://arxiv.org/abs/1103.5468 , 71kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5492 (*cross-listing*) Date: Mon, 28 Mar 2011 21:24:04 GMT (109kb) Title: $H(z)$ diagnostics on the nature of dark energy Authors: Sergio del Campo, Ramon Herrera and Diego Pavon Categories: astro-ph.CO gr-qc hep-ph hep-th Comments: 22 pages, 7 figures. Accepted for publication in IJMPD \\ The two dominant components of the cosmic budget today, pressureles matter and dark energy, may or may not be interacting with each other. Currently, both possibilities appear compatible with observational data. We propose several criteria based on the history of the Hubble factor that can help discern whether they are interacting and whether dark energy is phantom or quintessence in nature. \\ ( http://arxiv.org/abs/1103.5492 , 109kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5501 (*cross-listing*) Date: Mon, 28 Mar 2011 22:04:04 GMT (400kb) Title: Gamma-ray bursts as cosmological probes: LambdaCDM vs. conformal gravity Authors: Antonaldo Diaferio (1,2,3), Luisa Ostorero (1,2,3,4), Vincenzo F. Cardone (5), ((1) Universita` di Torino, (2) INFN Torino, (3) Harvard-Smithsonian Center for Astrophysics, (4) University of Pennsylvania, (5) INAF Monte Porzio Roma) Categories: astro-ph.CO gr-qc Comments: 18 pages, 12 figures, 4 tables, MNRAS submitted. Comments welcome \\ LambdaCDM, for the currently preferred cosmological density Omega_0 and cosmological constant Omega_Lambda, predicts that the Universe expansion decelerates down to redshift z~0.9 and accelerates at later times. On the contrary, the cosmological model based on conformal gravity predicts that the cosmic expansion has always been accelerating. To distinguish between these two very different cosmologies, we resort to gamma-ray bursts (GRBs), which have been suggested to probe the Universe expansion history at z>1, where identified type Ia supernovae (SNe) are rare. We use the full Bayesian approach to infer the cosmological parameters and the additional parameters required to describe the GRB data available in the literature. For the first time, we use GRBs as cosmological probes without any prior information from other data. In addition, when we combine the GRB samples with SNe, our approach neatly avoids all the inconsistencies of most numerous previous methods that are plagued by the so-called circularity problem. We find that the currently available SN and GRB samples are accommodated equally well by LambdaCDM and conformal gravity and do not exclude a continuous accelerated expansion. Nevertheless, the model selection method provided by the Bayesian approach decisively favours LambdaCDM. \\ ( http://arxiv.org/abs/1103.5501 , 400kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5587 (*cross-listing*) Date: Tue, 29 Mar 2011 10:09:22 GMT (24kb) Title: Status of Horava gravity: A personal perspective Authors: Matt Visser (Victoria University of Wellington) Categories: hep-th gr-qc Comments: 11 pages. Based on a talk at the ERE2010 conference, Granada, Spain, September 2010 \\ Horava gravity is a relatively recent (Jan 2009) idea in theoretical physics for trying to develop a quantum field theory of gravity. It is not a string theory, nor loop quantum gravity, but is instead a traditional quantum field theory that breaks Lorentz invariance at ultra-high (presumably trans-Planckian) energies, while retaining approximate Lorentz invariance at low and medium (sub-Planckian) energies. The challenge is to keep the Lorentz symmetry breaking controlled and small - small enough to be compatible with experiment. I will give a very general overview of what is going on in this field, paying particular attention to the disturbing role of the scalar graviton. \\ ( http://arxiv.org/abs/1103.5587 , 24kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5626 (*cross-listing*) Date: Tue, 29 Mar 2011 13:16:20 GMT (512kb,D) Title: Gamma ray burst delay times probe the geometry of momentum space Authors: Laurent Freidel and Lee Smolin Categories: hep-th gr-qc Comments: 21 pages, 13 figures \\ We study the application of the recently proposed framework of relative locality to the problem of energy dependent delays of arrival times of photons that are produced simultaneously in distant events such as gamma ray bursts. Within this framework, possible modifications of special relativity are coded in the geometry of momentum space. The metric of momentum space codes modifications in the energy momentum relation, while the connection on momentum space describes possible non-linear modifications in the laws of conservation of energy and momentum. In this paper, we study effects of first order in the inverse Planck scale, which are coded in the torsion and non-metricity of momentum space. We find that time delays of order Distance * Energies/m_p are coded in the non-metricity of momentum space. Current experimental bounds on such time delays hence bound the components of this tensor of order 1/m_p. We also find a new effect, whereby photons from distant sources can appear to arrive from angles slightly off the direction to the sources, which we call gravitational lensing. This is found to be coded into the torsion of momentum space. \\ ( http://arxiv.org/abs/1103.5626 , 512kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5635 (*cross-listing*) Date: Tue, 29 Mar 2011 13:32:14 GMT (18kb) Title: Conformal weights in the Kerr/CFT correspondence Authors: Keiju Murata Categories: hep-th gr-qc Comments: 19 pages \\ It has been conjectured that a near-extreme Kerr black hole is described by a 2d CFT. Previous work has shown that CFT operators dual to axisymmetric gravitational perturbations have integer conformal weights. In this paper, we study the analogous problem in 5d. We consider the most general near-extreme vacuum black hole with two rotational symmetries. This includes Myers-Perry black holes, black rings and Kaluza-Klein black holes. We find that operators dual to gravitational (or electromagnetic or massless scalar field) perturbations preserving both rotational symmetries have integer conformal weights, the same for all black holes considered. \\ ( http://arxiv.org/abs/1103.5635 , 18kb) ------------------------------------------------------------------------------ \\ arXiv:1103.5739 (*cross-listing*) Date: Tue, 29 Mar 2011 19:46:07 GMT (965kb) Title: A fully relativistic twisted disk around a slowly rotating Kerr black hole: derivation of dynamical equations and the shape of stationary configurations Authors: V. Zhuravlev and P. Ivanov Categories: astro-ph.HE astro-ph.CO gr-qc Comments: accepted for publication in MNRAS \\ (abbreviated) In this paper we derive equations describing dynamics and stationary configurations of a twisted fully relativistic thin accretion disc around a slowly rotating black hole. We find that the disc dynamics and stationary shapes are determined by a pair of equations for two complex variables describing orientation of the disc rings and velocity perturbations in the disc. We analyse shapes of stationary twisted configurations. It is shown that the stationary configurations depend on two parameters - the $\alpha $parameter and $\tilde \delta = \delta_{*}/\sqrt a$, where $\delta_{*}\sim h/r$ is the disc opening angle (h is the disc halfthickness) and $a$ is the black hole rotational parameter. When $a > 0$ and $\tilde \delta \ll 1$ the shapes depend drastically on value of $\alpha$. When $\alpha $ is small the disc inclination angle oscillates with radius with amplitude and radial frequency of the oscillations dramatically increasing towards the last stable orbit. For moderate values of $\alpha $ the oscillations do not take place but the disc does not align with the equatorial plane at small radii. Its inclination angle is either increasing towards $R_{ms}$ or exhibits a non-monotonic dependence on the radial coordinate. Finally, when $\alpha $ is sufficiently large the disc aligns with the equatorial plane at small radii. When $a < 0$ the disc aligns with the equatorial plane for all values of $\alpha $. The results reported here may have implications for determining structure and variability of accretion discs close to $R_{ms}$ as well as for modelling of emission spectra coming from different sources, which are supposed to contain black holes. \\ ( http://arxiv.org/abs/1103.5739 , 965kb) %%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%% ------------------------------------------------------------------------------ \\ arXiv:1007.1312 replaced with revised version Tue, 29 Mar 2011 19:21:02 GMT (34kb) Title: Spin induced multipole moments for the gravitational wave flux from binary inspirals to third Post-Newtonian order Authors: Rafael A. Porto, Andreas Ross and Ira Z. Rothstein Categories: gr-qc astro-ph.CO hep-ph hep-th Comments: 35 pages, 7 figures. Published version Journal-ref: JCAP 1103:009,2011 DOI: 10.1088/1475-7516/2011/03/009 \\ ( http://arxiv.org/abs/1007.1312 , 34kb) ------------------------------------------------------------------------------ \\ arXiv:1010.1757 replaced with revised version Tue, 29 Mar 2011 11:54:20 GMT (15kb) Title: Collapse and dispersal in massless scalar field models Authors: Swastik Bhattacharya, Rituparno Goswami, Pankaj S. Joshi Categories: gr-qc Comments: revised version, Accepted for publication in Int. Journ. of Mod. Phys. D, 6 pages, 3 figures \\ ( http://arxiv.org/abs/1010.1757 , 15kb) ------------------------------------------------------------------------------ \\ arXiv:1010.2481 replaced with revised version Mon, 28 Mar 2011 22:45:09 GMT (33kb) Title: Einstein gravity as a 3D conformally invariant theory Authors: Henrique Gomes, Sean Gryb and Tim Koslowski Categories: gr-qc hep-th Comments: 27 pages. Published version (minor changes and corrections) Journal-ref: Class.Quant.Grav.28:045005,2011 DOI: 10.1088/0264-9381/28/4/045005 \\ ( http://arxiv.org/abs/1010.2481 , 33kb) ------------------------------------------------------------------------------ \\ arXiv:1011.4847 (*cross-listing*) replaced with revised version Tue, 29 Mar 2011 19:18:09 GMT (18kb) Title: Tachyons in General Relativity Authors: Charles Schwartz Categories: math-ph gr-qc math.MP Comments: added references, minor correction near end of Section 7 \\ ( http://arxiv.org/abs/1011.4847 , 18kb) ------------------------------------------------------------------------------ \\ arXiv:1012.2374 replaced with revised version Mon, 28 Mar 2011 23:12:54 GMT (499kb) Title: Particle Creation by Naked Singularities in Higher Dimensions Authors: Umpei Miyamoto, Hiroya Nemoto, Masahiro Shimano Categories: gr-qc hep-th Comments: 1+14 pages, 3 figures, 1 table; v2: footnotes 1 and 5 added \\ ( http://arxiv.org/abs/1012.2374 , 499kb) ------------------------------------------------------------------------------ \\ arXiv:1101.1026 (*cross-listing*) replaced with revised version Tue, 29 Mar 2011 14:01:50 GMT (2052kb,D) Title: Cosmological structure formation with clustering quintessence Authors: Emiliano Sefusatti and Filippo Vernizzi Categories: astro-ph.CO gr-qc hep-th Comments: 36 pages, 11 figures. Replaced to match published version. Two figures added and minor revisions Report-no: t11/007 \\ ( http://arxiv.org/abs/1101.1026 , 2052kb) ------------------------------------------------------------------------------ \\ arXiv:1101.1935 (*cross-listing*) replaced with revised version Tue, 29 Mar 2011 12:25:40 GMT (258kb) Title: Modified Gravity or Dark Matter? Authors: J. W. Moffat Categories: astro-ph.CO gr-qc Comments: 14 pages, 5 figures, Talk given at the International conference on Two Cosmological Models, Universidad Iberoamericana, Ciudad de Mexico, November 17-19, 2010 \\ ( http://arxiv.org/abs/1101.1935 , 258kb) ------------------------------------------------------------------------------ \\ arXiv:1102.1163 replaced with revised version Mon, 28 Mar 2011 20:52:21 GMT (704kb,D) Title: Monopole Solutions in a Two Measure Field Theory and the Evolution of Vacuum Bubbles Authors: Alon Yaniv Categories: gr-qc \\ ( http://arxiv.org/abs/1102.1163 , 704kb) %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%--- For subscribe options to combined physics archives, e-mail To: physics@arXiv.org, Subject: subscribe ----------------------------------------------------------------------------- For help on viewing and making submissions, see http://arXiv.org/help/ For a list of archive mirror sites, see http://arXiv.org/servers.html ----------------------------------------------------------------------------- Third-party submissions cause excessive problems. 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