6161166
Dimming of Supernovae and Gamma-Ray Busts by Compton Scattering and Its Cosmological Implications
Free electrons deplete photons from Type Ia supernovae through the (inverse) Compton scattering. This Compton dimming increases with redshift and reaches 0.004 mag at z = 1 and 0.01 mag at z = 2. Although far from sufficient to invalidate the existence of dark energy, it can bias constraints on dark energy at a level nonnegligible for future supernova surveys. This effect is correctable and should be incorporated in supernova analysis. The Compton dimming has similar impact on cosmology based on gamma-ray bursts as standard candles.
14253775
SELF CALIBRATION OF GALAXY BIAS IN SPECTROSCOPIC REDSHIFT SURVEYS OF BARYON ACOUSTIC OSCILLATIONS
Baryon acousticoscillation (BAO)isapowerfulprobeon theexpansion oftheuniverse,sheddinglight on elusive dark energy and gravity atcosm ologicalscales. BAO m easurem entsthrough biased trac- ersofthe underlying m atterdensityeld,asm ostproposalsdo,can reach high statisticalaccuracy. However,possible scale dependence in biasm ay induce non-negligiblesystem aticalerrors,especially forthem ostam bitiousspectroscopicsurveysproposed.W eshow thatprecision spectroscopicredshift inform ation availablein thesesurveysallowsfor selfcalibration ofthegalaxybiasand itsstochasticity, as function ofscale and redshift. Through the eect ofredshift distortion,one can sim ultaneously m easure the realspace powerspectra ofgalaxies,galaxy-velocity and velocity,respectively. Atrel- evantscalesofBAO,galaxy velocity faithfully tracesthatofthe underlying m atter. This valuable feature enablesa ratherm odelindependentway to m easure the galaxy biasand itsstochasticity by com paring the three power spectra. For the square kilom eter array (SKA),this selfcalibration is statistically accurateto correctfor1% levelshiftin BAO peak positionsinduced by biasscaledepen- dence.Furtherm ore,wend thatSKA isabletodetectBAO in thevelocity powerspectrum ,opening a new window forBAO cosm ology. Subjectheadings: cosm ology:distancescale{large-scalestructureofuniverse{theory 1. IN TRO D U CTIO N
119098145
Behavior of f(R) gravity in the solar system, galaxies, and clusters
For cosmologically interesting f(R) gravity models, we derive the complete set of the linearized field equations in the Newtonian gauge, under environments of the solar system, galaxies, and clusters, respectively. Based on these equations, we confirm the previous gamma=1/2 solution in the solar system. However, f(R) gravity models can be strongly environment dependent and the high density (comparing to the cosmological mean) solar system environment can excite a viable gamma=1 solution for some f(R) gravity models. Although for f(R)proportional to-1/R, it is not the case; for f(R)proportional to-exp(-R/lambda H-2(0)2), such a gamma=1 solution does exist. This solution is virtually indistinguishable from that in general relativity (GR) and the value of the associated curvature approaches the GR limit, which is much higher than the value in the gamma=1/2 solution. We show that for some forms of f(R) gravity, this solution is physically stable in the solar system and can smoothly connect to the surface of the Sun. The derived field equations can be applied directly to gravitational lensing of galaxies and clusters. We find that, despite a significant difference in the environments of galaxies and clusters comparing to that of the solar system, gravitational lensing of galaxies and clusters can be virtually identical to that in GR, for some forms of f(R) gravity. Fortunately, galaxy rotation curve and intracluster gas pressure profile may contain valuable information to distinguish these f(R) gravity models from GR.
17627683
Confirmation of the Copernican principle at Gpc radial scale and above from the kinetic Sunyaev-Zel'dovich effect power spectrum.
The Copernican principle, a cornerstone of modern cosmology, remains largely unproven at the Gpc radial scale and above. Here will show that violations of this type will inevitably cause a first order anisotropic kinetic Sunyaev-Zel'dovich effect. If large scale radial inhomogeneities have an amplitude large enough to explain the "dark energy" phenomena, the induced kinetic Sunyaev-Zel'dovich power spectrum will be much larger than the Atacama Cosmology Telescope and/or South Pole Telescope upper limit. This single test confirms the Copernican principle and rules out the adiabatic void model as a viable alternative to dark energy.
31711511
Probing gravity at cosmological scales by measurements which test the relationship between gravitational lensing and matter overdensity.
The standard cosmology is based on general relativity (GR) and includes dark matter and dark energy and predicts a fixed relationship between the gravitational potentials responsible for gravitational lensing and the matter overdensity. Alternative theories of gravity often make different predictions. We propose a set of measurements which can test this relationship, thereby distinguishing between dark energy or matter models and models in which gravity differs from GR. Planned surveys will be able to measure E(G), an observational quantity whose expectation value is equal to the ratio of the Laplacian of the Newtonian potentials to the peculiar velocity divergence, to percent accuracy. This will easily separate alternatives such as the cold dark matter model with a cosmological constant, Dvali-Gabadadze-Porrati, TeVeS, and f(R) gravity.
119091401
The dark flow induced small-scale kinetic Sunyaev–Zel'dovich effect
Recently, Kashlinsky et al. reported a discovery of a similar to 10(3) km s(-1) bulk flow of the Universe out to z similar or equal to 0.3, through the dark flow induced cosmic microwave background (CMB) dipole in directions of clusters. We point out that, if this dark flow exists, it will also induce observable CMB temperature fluctuations at multipole l similar to 10(3), through modulation of the inhomogeneous electron distribution on the uniform dark flow. The induced small-scale kinetic Sunyaev-Zel'dovich (SZ) effect will reach similar to 1 mu K-2 at multipole 10(3) less than or similar to l less than or similar to 10(4), only a factor of similar to 2 smaller than the conventional kinetic SZ effect. Furthermore, it will be correlated with the large-scale structure (LSS) and its correlation with Two-Micron All-Sky Survey (2MASS) galaxy distribution reaches 0.3 mu K at l = 10(3), under a directional dependent optimal weighting scheme. We estimate that, Wilkinson Microwave Anisotropy Probe plus 2MASS should already be able to detect this dark flow induced small-scale kinetic SZ effect with similar to 6 sigma confidence. Deeper galaxy surveys such as the Sloan Digital Sky Survey can further improve the measurement. Planck plus existing galaxy surveys can reach greater than or similar to 14 sigma detection. Existing CMB-LSS cross-correlation measurements shall be reanalysed to test the existence of the dark flow and, if it exists, shall be used to eliminate possible bias on the integrated Sachs-Wolfe effect measurement through the CMB-LSS cross-correlation.
122389578
The order parameter field for cosmic string, inflation and dark energy
We present a whole frame for the cosmic strings, inflation and dark energy with the complex scalar field which can be regarded as the order parameter of our universe. One can find that the comic strings emerge in the zeros of the complex scalar field in the early universe. And with the evolution of complex scalar field, inflation and dark energy can be understood in this frame.
124274141
Wall vortices in the multi-component dual superconductor theory
119898079
Topological objects in the O(3) nonlinear sigma model
We study the topological defects in the nonlinear O(3) sigma model in terms of the decomposition of U(1) gauge potential. Time-dependent baby skyrmions are discussed in the (2+1)-dimensional spacetime with the CP1 field. Furthermore, we show that there are three kinds of topological defects–vortex lines, point defects and knot exist in the (3+1)-dimensional model, and their topological charges, locations and motions are determined by the ϕ-mapping topological current theory.
32996904
Higher order modes in third harmonic cavities for XFEL/FLASH
We analyse higher order modes in the 3.9 GHz bunch shaping cavities recently installed in the FLASH facility at DESY. We report on recent experimental results on the frequency spectrum from probe based measurements made at CMTB at DESY. These are compared to those predicted by finite difference and finite element computer codes. This study is focused mainly on the dipole component of the multi-pole expansion of the wakefield. The modes are readily identifiable as single-cavity modes provided the frequencies of these modes are below the cut-off of the inter-connecting beam pipes. The modes above cut-off are coupled to the 4 cavities and are distinct from single cavity modes.
119277755
Nucleon Momentum Decomposition in QCD
~Based on the gauge invariant quark canonical momentum we construct two theoretically possible decompositions of nucleon momentum to those of quarks and gluons. We predict that either 6% or 21% of nucleon momentum is carried by gluons, depending on what type of gluons are in nucleons. We clarify the existing confusions on this problem and discuss the physical implications of our result on the proton spin crisis problem.