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Jun 29, 2018
06/18

by
Michael Boylan-Kolchin; Daniel R. Weisz; James S. Bullock; Michael C. Cooper

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Near-field cosmology -- using detailed observations of the Local Group and its environs to study wide-ranging questions in galaxy formation and dark matter physics -- has become a mature and rich field over the past decade. There are lingering concerns, however, that the relatively small size of the present-day Local Group ($\sim 2$ Mpc diameter) imposes insurmountable sample-variance uncertainties, limiting its broader utility. We consider the region spanned by the Local Group's progenitors at...

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, Astrophysics of Galaxies

Source: http://arxiv.org/abs/1603.02679

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4.0

Jun 30, 2018
06/18

by
Ronaldo S. S. Vieira; Włodek Kluźniak; Marek Abramowicz

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The sum of squared epicyclic frequencies of nearly circular motion ($\omega_r^2+\omega_\theta^2$) in axially symmetric configurations of Newtonian gravity is known to depend both on the matter density and on the angular velocity profile of circular orbits. It was recently found that this sum goes to zero at the photon orbits of Schwarzschild and Kerr spacetimes. However, these are the only relativistic configurations for which such result exists in the literature. Here, we extend the above...

Topics: General Relativity and Quantum Cosmology, High Energy Astrophysical Phenomena, Cosmology and...

Source: http://arxiv.org/abs/1701.08873

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Jun 29, 2018
06/18

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James Bonifacio; Kurt Hinterbichler; Rachel A. Rosen

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We derive analyticity constraints on a nonlinear ghost-free effective theory of a massive spin-2 particle known as pseudo-linear massive gravity, and on a generalized theory of a massive spin-1 particle, both of which provide simple IR completions of Galileon theories. For pseudo-linear massive gravity we find that, unlike dRGT massive gravity, there is no window of parameter space which satisfies the analyticity constraints. For massive vectors which reduce to Galileons in the decoupling...

Topics: High Energy Physics - Theory, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1607.06084

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Jun 29, 2018
06/18

by
Seema Satin; H. T. Cho; Bei Lok Hu

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For a conformally-coupled scalar field we obtain the conformally-related Einstein-Langevin equations, using appropriate transformations for all the quantities in the equations between two conformally-related spacetimes. In particular, we analyze the transformations of the influence action, the stress energy tensor, the noise kernel and the dissipation kernel. In due course the fluctuation-dissipation relation is also discussed. The analysis in this paper thereby facilitates a general solution...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1603.06206

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Jun 29, 2018
06/18

by
Ran Wang; Xue-Bing Wu; Roberto Neri; Xiaohui Fan; Fabian Walter; Chris L. Carilli; Emmanuel Momjian; Frank Bertoldi; Michael A. Strauss; Qiong Li; Feige Wang; Dominik A. Riechers; Linhua Jiang; Alain Omont; Jeff Wagg; Pierre Cox

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We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the ultraluminous quasar SDSSJ010013.02+280225.8 (hereafter, J0100+2802) at z=6.3, which hosts the most massive supermassive black hole (SMBH) of 1.24x10^10 Msun known at z>6. We detect the [C II] 158 $\mu$m fine structure line and molecular CO(6-5) line and continuum emission at 353 GHz, 260 GHz, and 3 GHz from this quasar. The CO(2-1) line and the underlying continuum at 32 GHz are also marginally detected. The [C II] and CO...

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, Astrophysics of Galaxies

Source: http://arxiv.org/abs/1606.09634

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Jun 30, 2018
06/18

by
Sushant G. Ghosh; Uma Papnoi; Sunil D. Maharaj

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Lovelock theory is a natural extension of the Einstein theory of general relativity to higher dimensions in which the first and second orders correspond, respectively, to general relativity and Einstein-Gauss-Bonnet gravity. We present exact black hole solutions of $D\geq 4$-dimensional spacetime for first-, second-, and third-order Lovelock gravities in a string cloud background. Further, we compute the mass, temperature, and entropy of black hole solutions for the higher-dimensional general...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.4611

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Topics: Radio Program, Christian theology, Judeo-Christian topics, Ancient Israel and Judah, God, Names of...

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4.0

Jun 30, 2018
06/18

by
Slobodan Prvanovic

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Within the framework of self-adjoint operator of time in non-relativistic quantum mechanics the equation describing change of the state of quantum system with respect to energy is introduced. The operator of time appears to be the generator of the change of energy while the operator of energy, that is conjugate to the operator of time, generates time evolution in this proposal. Two examples, one with discrete time and the other with continuous one, are given and the generalization of...

Topics: General Relativity and Quantum Cosmology, Quantum Physics

Source: http://arxiv.org/abs/1701.05244

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Jun 30, 2018
06/18

by
Yi-Fu Cai; Jerome Quintin; Emmanuel N. Saridakis; Edward Wilson-Ewing

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We confront various nonsingular bouncing cosmologies with the recently released BICEP2 data and investigate the observational constraints on their parameter space. In particular, within the context of the effective field approach, we analyze the constraints on the matter bounce curvaton scenario with a light scalar field, and the new matter bounce cosmology model in which the universe successively experiences a period of matter contraction and an ekpyrotic phase. Additionally, we consider three...

Topics: High Energy Physics - Theory, Astrophysics, General Relativity and Quantum Cosmology, Cosmology and...

Source: http://arxiv.org/abs/1404.4364

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3.0

Jun 30, 2018
06/18

by
Pedro Labrana

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We present an alternative scheme for an Emergent Universe scenario, developed previously in $Phys.\ Rev.\ D {\bf 86}, 083524 (2012)$, where the universe is initially in a static state supported by a scalar field located in a false vacuum. The universe begins to evolve when, by quantum tunneling, the scalar field decays into a state of true vacuum. The Emergent Universe models are interesting since they provide specific examples of non-singular inflationary universes.

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1406.0922

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Jun 29, 2018
06/18

by
Qing-Guo Huang; Shi Pi

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The effects of heavy fields modulate the scalar power spectrum during inflation. We analytically calculate the modulations of the scalar power spectrum from a heavy field with a separable monomial potential, i.e. V(\phi)~\phi^n. In general the modulation is characterized by a power-law oscillation which is reduced to the logarithmic oscillation in the case of n=2.

Topics: High Energy Physics - Theory, Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1610.00115

Topics: Radio Program, Physical cosmology, Oral hygiene, Energy, Speculative fiction, American politicians,...

3
3.0

Jun 28, 2018
06/18

by
Ryan Cooke; Max Pettini

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We determine the relative ionization of deuterium and hydrogen in low metallicity damped Lyman-alpha (DLA) and sub-DLA systems using a detailed suite of photoionization simulations. We model metal-poor DLAs as clouds of gas in pressure equilibrium with a host dark matter halo, exposed to the Haardt & Madau (2012) background radiation of galaxies and quasars at redshift z~3. Our results indicate that the deuterium ionization correction correlates with the H I column density and the ratio of...

Topics: Cosmology and Nongalactic Astrophysics, Astrophysics, Astrophysics of Galaxies

Source: http://arxiv.org/abs/1510.03867

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Jun 30, 2018
06/18

by
Cameron Thacker; Yan Gong; Asantha Cooray; Francesco De Bernardis; Joseph Smidt; Ketron Mitchell-Wynne

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We present the cross-correlation between the far-infrared background fluctuations as measured with the Herschel Space Observatory at 250, 350, and 500 {\mu}m and the near-infrared background fluctuations with Spitzer Space Telescope at 3.6 {\mu}m. The cross-correlation between far and near-IR background anisotropies are detected such that the correlation coefficient at a few to ten arcminute angular scales decreases from 0.3 to 0.1 when the far-IR wavelength increases from 250 {\mu}m to 500...

Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1412.4009

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2.0

Jun 30, 2018
06/18

by
Nobuyuki Motoyui

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The cosmological observation indicates that the effective equation of state parameter $w_{eff}$ varies with $z$: It changes from $w_{eff}>-1$ to $w_{eff}

Topics: High Energy Physics - Theory, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1411.3845

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Jun 30, 2018
06/18

by
Yi-Fu Cai; Yi Wang

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Inspired by quantum gravitational physics, the approach of non-commutative (NC) phase space leads to a modified dispersion relation of gravitational waves. This feature, if applied to the very early universe, gives rise to a modified power spectrum of primordial tensor perturbations with a suppression of power on large scales. We confront this phenomenon with the BICEP2 and Planck experiments, and show that inflation with the modified dispersion relation can simultaneously fit the observations...

Topics: High Energy Physics - Theory, High Energy Physics - Phenomenology, Astrophysics, General Relativity...

Source: http://arxiv.org/abs/1404.6672

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Topics: Radio Program, Incorporated cities and towns in California, NPR programs, Political terminology,...

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5.0

Jun 29, 2018
06/18

by
Ramon Herrera; W. S. Hipolito-Ricaldi; Nelson Videla

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In this paper we investigate the consequences of phantom crossing considering the perturbative dynamics in models with interaction in their dark sector. By mean of a general study of gauge-invariant variables in comoving gauge, we relate the sources of instabilities in the structure formation process with the phantom crossing. In order to illustrate these relations and its consequences in more detail, we consider a specific case of an holographic dark energy interacting with dark matter. We...

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1607.01806

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4.0

Jun 30, 2018
06/18

by
William A. Dawson; Michael D. Schneider; J. Anthony Tyson; M. James Jee

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Using overlapping fields with space-based Hubble Space Telescope (HST) and ground-based Subaru Telescope imaging we identify a population of blended galaxies that are blended to such a large degree that they are detected as single objects in the ground-based monochromatic imaging, which we label as 'ambiguous blends'. For deep imaging data, such as the depth targeted with the Large Synoptic Survey Telescope (LSST), the ambiguous blend population is both large ($\sim 14$%) and has a distribution...

Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1406.1506

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Jun 30, 2018
06/18

by
Sayantan Choudhury

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In this paper I provide a general framework based on $\delta N$ formalism to study the features of unavoidable higher dimensional non-renormalizable K\"ahler operators for ${\cal N}=1$ supergravity (SUGRA) during primordial inflation from the combined constraint on non-Gaussianity, sound speed and CMB dipolar asymmetry as obtained from the recent Planck data. In particular I study the nonlinear evolution of cosmological perturbations on large scales which enables us to compute the...

Topics: High Energy Physics - Theory, High Energy Physics - Phenomenology, Astrophysics, General Relativity...

Source: http://arxiv.org/abs/1402.1251

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Jun 29, 2018
06/18

by
Vladimir A. Belinski

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In the present letter we indicate an extension of the pure gravity inverse scattering integration technique to the case when fermions (introduced on the base of supersymmetry) are present. In this way the integrability technique for simple ($N=1$) supergravity in two space-time dimensions coupled to the matter fields taking values in the Lie algebra of $E_{8\left( +8\right) }$ group is developed. This theory contains matter living only in one Weyl representation of $SO\left( 16\right) $ and...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1611.02924

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Topics: Radio Program, Physical cosmology, American murderers of children, American serial killers, General...

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3.0

Jun 30, 2018
06/18

by
Naritaka Oshita; Kazuhiro Yamamoto; Sen Zhang

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We investigate Brownian motions of a particle coupled to vacuum fluctuations of a quantum field. The Unruh effect predicts that an observer in an accelerated motion sees the Minkowski vacuum as thermally excited. This addresses the problem of whether a thermal property appears in a perturbative random motion of a particle in an accelerated motion due to the coupling or not. We revisit this problem by solving the equation of motion of a particle coupled to vacuum fluctuations including the...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1403.5028

Topics: Radio Program, Western Europe, Island countries, Political science, International trade,...

Topics: Radio Program, Physical cosmology, Divided regions, East Asian countries, Theoretical physicists,...

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Jun 30, 2018
06/18

by
Rhythm Shimakawa; Tadayuki Kodama; Charles C. Steidel; Ken-ichi Tadaki; Ichi Tanaka; Allison L. Strom; Masao Hayashi; Yusei Koyama; Tomoko L. Suzuki; Moegi Yamamoto

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In the redshift interval of $2

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1411.1408

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3.0

Jun 29, 2018
06/18

by
A. Bendjoudi; N. Mebarki

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The convex hull on three points in two dimensional euclidean space of three flat edges (trihedron) was studied. The Bohr-Sommerfeld quantization of the area of space is performed. It is shown that it reproduces exactly the equidistant spacing spectrum found elsewhere.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1611.00619

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3.0

Jun 30, 2018
06/18

by
Tim Taves

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We first derive the Hamiltonian for Lovelock gravity and find that it takes the same form as in general relativity when written in terms of the Misner-Sharp mass function. We then minimally couple the action to matter fields to find Hamilton's equations of motion. These are gauge fixed to be in the Painlev\'e-Gullstrand co-ordinates and are well suited to numerical studies of black hole formation. We then use these equations of motion for the massless scalar field to study the formation of...

Topics: High Energy Physics - Theory, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.2241

Topics: Radio Program, Dark matter, Nobel Peace Prize, Female heads of government, Physical cosmology,...

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3.0

Jun 29, 2018
06/18

by
Andrea Passamonti; José A. Pons

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We study the torsional magneto-elastic oscillations of relativistic superfluid magnetars and explore the effects of a phase transition in the crust-core interface (nuclear pasta) which results in a weaker elastic response. Exploring various models with different extension of nuclear pasta phases, we find that the differences in the oscillation spectrum present in purely elastic modes (weak magnetic field), are smeared out with increasing strength of the magnetic field. For magnetar conditions,...

Topics: Astrophysics, High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics, General...

Source: http://arxiv.org/abs/1606.02132

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Jun 30, 2018
06/18

by
Guillermo Ballesteros; J. Alberto Casas

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If a sizeable tensor-to-scalar ratio ~0.1 turns out to be detected and a negative running of the scalar spectral index ~0.01 is significantly required by the data, the vast majority of single field models of inflation will be ruled out. We show that a flat tree-level effective potential, lifted by radiative corrections and by the imprints of a high energy scale (in the form of non-renormalizable operators) can explain those features and produce enough inflation in the slow-roll regime.

Topics: High Energy Physics - Theory, High Energy Physics - Phenomenology, Astrophysics, General Relativity...

Source: http://arxiv.org/abs/1406.3342

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2.0

Jun 30, 2018
06/18

by
David Maxwell

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The conformal method developed in the 1970s and the more recent Lagrangian and Hamiltonian conformal thin-sandwich methods are techniques for finding solutions of the Einstein constraint equations. We show that they are manifestations of a single conformal method: there is a straightforward way to convert back and forth between the parameters for these methods so that the corresponding solutions of the Einstein constraint equations agree. The unifying idea is the need to clearly distinguish...

Topics: Mathematics, Mathematical Physics, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1402.5585

Topics: Radio Program, Christian terms, Universe, Physical cosmology, Energy conservation, Educational...

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5.0

Jun 29, 2018
06/18

by
Athanasios Bakopoulos; Panagiota Kanti

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In this work, we focus on the theory of Gravito-Electromagnetism (GEM) -- the theory that describes the dynamics of the gravitational field in terms of quantities met in Electromagnetism -- and we propose two novel forms of metric perturbations. The first one is a generalisation of the traditional GEM ansatz, and succeeds in reproducing the whole set of Maxwell's equations even for a dynamical vector potential A. The second form, the so-called alternative ansatz, goes beyond that leading to an...

Topics: High Energy Physics - Theory, Astrophysics, Cosmology and Nongalactic Astrophysics, General...

Source: http://arxiv.org/abs/1610.09819

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Jun 30, 2018
06/18

by
Saoussen Mbarek; M. B. Paranjape

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We study the possibility of the existence of negative mass bubbles within a de Sitter space-time background with matter content corresponding to a perfect fluid. It is shown that there exist configurations of the perfect fluid, that everywhere satisfy the dominant energy condition, the Einstein equations and the equations of hydrostatic equilibrium, however asymptotically approach the exact solution of Schwarzschid-de Sitter space-time with a negative mass.

Topics: High Energy Physics - Theory, Mathematics, Mathematical Physics, General Relativity and Quantum...

Source: http://arxiv.org/abs/1407.1457

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Jun 28, 2018
06/18

by
O. Bertolami; V. Bessa; J. Páramos

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We study the possibility that inflation is driven by a massive vector field with SO(3) global symmetry nonminimally coupled to gravity. From an E^3-invariant Robertson-Walker metric we propose an Ansatz for the vector field, allowing us to study the evolution of the system. We study the behaviour of the equations of motion using the methods of the theory of dynamical systems and find exponential inflationary regimes.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1511.03520

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Jun 30, 2018
06/18

by
Eduardo Rozo; Eli S. Rykoff; Matthew Becker; Rachel M. Reddick; Risa H. Wechsler

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In order to study the galaxy population of galaxy clusters with photometric data one must be able to accurately discriminate between cluster members and non-members. The redMaPPer cluster finding algorithm treats this problem probabilistically. Here, we utilize SDSS and GAMA spectroscopic membership rates to validate the redMaPPer membership probability estimates for clusters with $z\in[0.1,0.3]$. We find small - but correctable - biases, sourced by three different systematics. The first two...

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1410.1193

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Jun 30, 2018
06/18

by
Taishi Katsuragawa; Shin'ichi Nojiri

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We study the stability under the perturbation and the related anti-evaporation of the Nariai space-time in bigravity. If we impose specific condition for the solutions and parameters, we obtain asymptotically de Sitter space-time, and show the existence of the Nariai space-time as a background solution. Considering the perturbation around the Nariai space-time up to first order, we investigate the behavior of black hole horizon. We show that the anti-evaporation does not occur on the classical...

Topics: High Energy Physics - Theory, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1411.1610

Topics: Radio Program, Association of American Universities, National Association of Independent Colleges...

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Jun 28, 2018
06/18

by
John Joseph M. Carrasco; Renata Kallosh; Andrei Linde

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We construct inflationary models in the context of supergravity with orthogonal nilpotent superfields [1]. When local supersymmetry is gauge-fixed in the unitary gauge, these models describe theories with only a single real scalar (the inflaton), a graviton and a gravitino. Critically, there is no inflatino, no sgoldstino, and no sinflaton in these models. This dramatically simplifies cosmological models which can simultaneously describe inflation, dark energy and SUSY breaking.

Topics: High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics, Astrophysics, General...

Source: http://arxiv.org/abs/1512.00546

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Jun 28, 2018
06/18

by
Matthew D. Kistler

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The steep spectrum of neutrinos measured by IceCube extending from >1 PeV down to ~10 TeV has an energy flux now encroaching on the Fermi isotropic GeV background. We examine several implications starting from source energetics requirements for neutrino production. We show how the environment of extragalactic nuclei can extinguish ~10-100 TeV gamma rays and convert their energy to X-rays for plausible conditions of infrared luminosity and magnetic field, so that the Fermi background is not...

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, Astrophysics of Galaxies, High Energy...

Source: http://arxiv.org/abs/1511.01530

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3.0

Jun 29, 2018
06/18

by
Zhe Chang; Chao-Guang Huang; Zhi-Chao Zhao

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Recently, the LIGO Scientific Collaboration and Virgo Collaboration published the second observation on gravitational wave GW151226 [Phys. Rev. Lett. 116, 241103 (2016)] from the binary black hole coalescence with initial masses about 14 M$_\odot$ and 8 M$_\odot$. They claimed that the peak gravitational strain was reached at about 450 Hz, the inverse of which has been longer than the average time a photon staying in the Fabry-Perot cavities in two arms. In this case, the phase-difference of a...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1612.01615

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Jun 30, 2018
06/18

by
Sumanta Chakraborty; Soumitra SenGupta

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This work presents a general formalism to analyze a generic bulk scalar field in a multiple warped extra-dimensional model with arbitrary number of extra dimensions. The Kaluza-Klein mass modes along with the self-interaction couplings are determined and the possibility of having lowest lying KK mode masses near TeV scale are discussed. Also some numerical values for low-lying KK modes has been presented showing explicit localization around TeV scale. It is argued that the appearance of large...

Topics: High Energy Physics - Theory, High Energy Physics - Phenomenology, General Relativity and Quantum...

Source: http://arxiv.org/abs/1401.3279

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Jun 30, 2018
06/18

by
S. Jalalzadeh; T. Rostami; P. V. Moniz

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A framework associating quantum cosmological boundary conditions to minisuperspace hidden symmetries has been introduced in \cite{7}. The scope of the application was, notwithstanding the novelty, restrictive because it lacked a discussion involving realistic matter fields. Therefore, in the herein letter, we extend the framework scope to encompass elements from a scalar-tensor theory in the presence of a cosmological constant. More precisely, it is shown that hidden minisuperspace symmetries...

Topics: High Energy Physics - Theory, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1412.6439

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Jun 29, 2018
06/18

by
Zhen Pan; Lloyd Knox; Brigid Mulroe; Ali Narimani

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The Planck collaboration has measured the temperature and polarization of the cosmic microwave background well enough to determine the locations of eight peaks in the temperature (TT) power spectrum, five peaks in the polarization (EE) power spectrum and twelve extrema in the cross (TE) power spectrum. The relative locations of these extrema give a striking, and beautiful, demonstration of what we expect from acoustic oscillations in the plasma; e.g., that EE peaks fall half way between TT...

Topics: Astrophysics, Cosmology and Nongalactic Astrophysics

Source: http://arxiv.org/abs/1603.03091

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Jun 28, 2018
06/18

by
C. Sofia Carvalho; Katrine Marques

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We develop a method based on the angular distribution on the sky of cosmological parameters to probe the inhomogeneity of large-scale structure and cosmic acceleration. We demonstrate this method on the largest type Ia supernova (SN) data set available to date, as compiled by the Joint Light-curve Analysis (JLA) collaboration and, hence, consider the cosmological parameters that affect the luminosity distance. We divide the supernova sample into equal surface area pixels and estimate the...

Topics: Cosmology and Nongalactic Astrophysics, Astrophysics

Source: http://arxiv.org/abs/1512.07869

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Jun 30, 2018
06/18

by
D. G. Cerdeno; C. Cuesta; M. Fornasa; E. Garcia; C. Ginestra; C. Marcos; M. Martinez; Y. Ortigoza; M. Peiro; J. Puimedon; M. L. Sarsa

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In the last decade direct detection Dark Matter (DM) experiments have increased enormously their sensitivity and ton-scale setups have been proposed, especially using germanium and xenon targets with double readout and background discrimination capabilities. In light of this situation, we study the prospects for determining the parameters of Weakly Interacting Massive Particle (WIMP) DM (mass, spin-dependent (SD) and spin-independent (SI) cross section off nucleons) by combining the results of...

Topics: Instrumentation and Methods for Astrophysics, High Energy Physics - Phenomenology, Astrophysics,...

Source: http://arxiv.org/abs/1403.3539

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2.0

Jun 28, 2018
06/18

by
S. H. Hendi; A. Sheykhi; S. Panahiyan; B. Eslam Panah

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In this paper, we consider a linearly charged dilatonic black holes and study their thermodynamical behavior in the context of phase transition and thermodynamic geometry. We show that, depending on the values of the parameters, these type of black holes may enjoy two types of phase transition. We also find that there are three critical behaviors near the critical points for these black holes; nonphysical unstable to physical stable, large to small, and small to large black holes phase...

Topics: General Relativity and Quantum Cosmology, High Energy Physics - Theory

Source: http://arxiv.org/abs/1509.08593

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Jun 29, 2018
06/18

by
Maresuke Shiraishi; Julian B. Muñoz; Marc Kamionkowski; Alvise Raccanelli

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Most inflationary models predict primordial perturbations to be statistically isotropic and homogeneous. Cosmic microwave background (CMB) observations, however, indicate a possible departure from statistical isotropy in the form of a dipolar power modulation at large angular scales. Alternative models of inflation, beyond the simplest single-field slow-roll models, can generate a small power asymmetry, consistent with these observations. Observations of clustering of quasars show, however,...

Topics: Astrophysics, High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics, General...

Source: http://arxiv.org/abs/1603.01206

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Jun 28, 2018
06/18

by
Jia-An Lu

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In de Sitter (dS) gravity, where gravity is a gauge field introduced to realize the local dS invariance of the matter field, two kinds of conservation laws are derived. The first kind is a differential equation for a dS-covariant current, which unites the canonical energy-momentum (EM) and angular momentum (AM) tensors. The second kind presents a dS-invariant current which is conserved in the sense that its torsion-free divergence vanishes. The dS-invariant current unites the total (matter plus...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1508.01981