18640620
Predicting the polarization of the microwave background from the WMAP temperature maps
Abstract In this paper, we study how to predict the polarization of the Cosmic Microwave Background (CMB) using knowledge of only the temperature (intensity) and the cross-correlation between temperature and polarization. We derive a “Wiener prediction” method and apply it to the Wilkinson Microwave Anisotropy Probe (WMAP) all-sky CMB temperature maps and to the MAXIMA field.
119468667
Gravitational Waves Probe the Coalescence Rate of Massive Black Hole Binaries
We calculate the expected nHz-μHz gravitational wave (GW) spectrum from coalescing massive black hole (MBH) binaries resulting from mergers of their host galaxies. We consider detection of this spectrum by precision pulsar timing and a future pulsar timing array. The spectrum depends on the merger rate of massive galaxies, the demographics of MBHs at low and high redshift, and the dynamics of MBH binaries. We apply recent theoretical and observational work on all of these fronts. The spectrum has a characteristic strain hc(f) ~ 10-15(f/yr-1)-2/3, just below the detection limit from recent analysis of precision pulsar timing measurements. However, the amplitude of the spectrum is still very uncertain owing to approximations in the theoretical formulation of the model, to our lack of knowledge of the merger rate and MBH population at high redshift, and to the dynamical problem of removing enough angular momentum from the MBH binary to reach a GW-dominated regime.
119408227
CMB likelihood functions for beginners and experts
Although the broad outlines of the appropriate pipeline for cosmological likelihood analysis with CMB data has been known for several years, only recently have we had to contend with the full, large-scale, computationally challenging problem involving both highly-correlated noise and extremely large datasets (N>1000). In this talk we concentrate on the beginning and end of this process. First, we discuss estimating the noise covariance from the data itself in a rigorous and unbiased way; this is essentially an iterated minimum-variance mapmaking approach. We also discuss the unbiased determination of cosmological parameters from estimates of the power spectrum or experimental bandpowers.
15621530
Constraining large–scale structure theories with the cosmic background radiation
The case is strong that cosmic microwave background (CMB) and large scale structure (LSS) observations can be combined to determine the theory of structure formation and the cosmological parameters that define it. We review: the relevant (10+) parameters associated with the inflation model of fluctuation generation and the matter content of the universe; the relation between LSS and primary and secondary CMB anisotropy probes as a function of wavenumber; how COBE constraints on energy injection rule out explosions as a dominant source of LSS; and how current anisotropy band–powers in multipole–space, at levels ca. 10−5)2, strongly support the gravitational instability theory and suggest the universe could not have reionized too early. We use Bayesian analysis methods to determine what current CMB and CMB+LSS data imply for inflation–based Gaussian fluctuations in tilted &Lgr;CDM, &Lgr;hCDM and oCDM model sequences with cosmological age 11 – 15 Gyr, consisting of mixtures of baryons, cold ‘c’ (and possibly hot ‘h’) dark matter, vacuum energy &Lgr;, and curvature energy ‘o’ in open cosmologies. For example, we find the slope of the initial spectrum is within about 5% of the (preferred) scale–invariant form when just the CMB data are used, and for &Lgr;CDM when LSS data are combined with CMB; with both, a non–zero value of Ω&Lgr; is strongly preferred (ca. ⅔ for a 13 Gyr sequence, similar to the value from SNIa). The oCDM sequence prefers Ωtot < 1, but is overall much less likely than the flat Ω&Lgr; ≠ 0 sequence with CMB+LSS. We also review the rosy forecasts of angular power spectra and parameter estimates from future balloon and satellite experiments when foreground and systematic effects are ignored to show where cosmic parameter determination can go with CMB information alone.
122687802
Imaging the early universe with the BOOMERanG Experiment
The BOOMERanG experiment has recently detected temperature fluctuations the Cosmic Microwave Background (CMB), the otherwise isotropic radiation coming from the early Universe. These anisotropies have a low contrast (about 30 ppm) and feature a peculiar angular power spectrum at angles corresponding to sub-horizon scales at recombination. In the current cosmological model, these structures result from acoustic oscillations in the primeval plasma. In the framework of the Hot Big Bang theory with the inflationary hypothesis, the statistical properties of the image of the CMB allow us to measure most of the cosmological parameters.
17460509
Simultaneous Estimation of Noise and Signal in Cosmic Microwave Background Experiments
To correctly analyse data sets from current microwave detection technology, one is forced to estimate the sky signal and experimental noise simultaneously. Given a time-ordered data set we propose a formalism and method for estimating the signal and associated errors without prior knowledge of the noise power spectrum. We derive the method using a Bayesian formalism and relate it to the standard methods; in particular we show how this leads to a change in the estimate of the noise covariance matrix of the sky signal. We study the convergence and accuracy of the method on two mock observational strategies and discuss its application to a currently-favoured calibration procedure.
121225135
Asymptotically commuting families of operators
We study families of symmetric operators (Qn) with domains given by the range of self-adjoint contraction semigroups (e−tHn). Assuming the asymptotic commutativity, limn[Qn, e−tHn]=0, and certain other estimates, we establish the existence and properties of a limiting self-adjoint operatorQ=limnQn. We apply these results to the study of an elementary supersymmetry algebra.
118621285
A convergent expansion about mean field theory: I. The expansion
A convergent expansion in the multiphase region is given for nearly Gaussian quantum field theory. The expansion combines (1) an expansion in phase boundaries, (2) a cluster expansion, and (3) a perturbation expansion to isolate dominant behavior. The ground state of the P (phi)/sub 2/= (lambdaphi/sup 4/-phi/sup 2/-..mu..phi)/sub 2/ model is studied, with mod ..mu.. < or =lambda/sup 2/very-much-less-than1. The ground state is close to the classical free field, obtained by replacing P (phi) by the quadratic mean field polynomial P/sub c/(phi), tangent to P at a global minimum. Selecting one minimum gives a pure phase (ergodic ground state) satisfying the Wightman-Osterwalder-Schrader axioms with a positive mass. Analyticity is established in lambda for ..mu..=0 in the sector Imlambda
122562768
Euclidean quantum field theory
Quantification de la theorie euclidienne. Particules de spin eleve. Probabilite et theorie du champ constructive
118568324
Classical Gauge Theories and Their Quantum Role
The classical Euclidean variational equations (δA= 0, where A is the action functional, play two important roles. First, in dimension d ≤ 3 they provide time independent solutions to classical four-dimensional physics. In that way, for example, the Ginzburg-Landau model has proved important in the theory of superconductivity. The second role of Euclidean stationary points of the action is to provide a starting point for classical approximations to quantum fields. We make some remarks on these two topics; for classical gauge theories we restrict attention to the Higgs model.
122859727
Charges, vortices and confinement
Abstract We study the confinement phase transition. We point out the relation between the decay rates of the Wilson loop integral, Osterwalder and Seiler's n -ality restriction, and Polyakov and 't Hooft's analysis of the center of the gauge group. Vortices and merons are analyzed as possible mechanisms to produce disorder in the center. We show how to realize the 't Hooft commutation relations, and we estimate the critical coupling for vortices to be in approximate agreement with the critical coupling determined by Callan, Dashen and Gross from the analysis of instantons.