Constraining Cosmological Parameters with Gravitational Lensing of the Cosmic Microwave Background


Book Description

"The cosmic microwave background (CMB) anisotropies are a direct probe of early Universe physics. They also carry information about the late Universe through different secondary effects, including gravitational lensing. Propagating away from the last scattering surface, the primary CMB photons are deflected by the intervening large-scale structure, creating slight distortions in the CMB radiation temperature and polarization patterns that can be detected statistically. In this thesis, we present constraints on the parameters describing our Universe on cosmological scales obtained with the use of CMB gravitational lensing measurements. We begin with a description of the current cosmological model and follow with a review of gravitational lensing effects on the CMB observables.We then present bounds on cosmological parameters set by the lensing power spectrum estimated from a combined SPT+Planck CMB temperature map on the SPT-SZ 2500 square-degrees patch of sky.Adding lensing information to primary CMB data helps tightening constraints on cosmological parameters affecting late-time growth, such as the matter fluctuation amplitude today, the spatial curvature and the sum of neutrino masses.Measurements of the CMB polarization sourced in the early Universe are hindered by the additional polarization created by the gravitational lensing deflections; this contaminating lensing signal can be estimated and removed. We discuss projected constraints on the scale-dependence of the primordial CMB polarization signal assuming that the lensing induced contamination can be subtracted through different scenarios." --







Fundamental Parameters in Cosmology


Book Description







One Hundred Years Of General Relativity: From Genesis And Empirical Foundations To Gravitational Waves, Cosmology And Quantum Gravity - Volume 2


Book Description

The aim of this two-volume title is to give a comprehensive review of one hundred years of development of general relativity and its scientific influences. This unique title provides a broad introduction and review to the fascinating and profound subject of general relativity, its historical development, its important theoretical consequences, gravitational wave detection and applications to astrophysics and cosmology. The series focuses on five aspects of the theory: The first three topics are covered in Volume 1 and the remaining two are covered in Volume 2. While this is a two-volume title, it is designed so that each volume can be a standalone reference volume for the related topic.




Principles of Gravitational Lensing


Book Description

This textbook provides an introduction to gravitational lensing, which has become an invaluable tool in modern astrophysics, with applications that range from finding planets orbiting distant stars to understanding how dark matter and dark energy conspired to form the cosmic structures we see today. Principles of Gravitational Lensing begins with Einstein’s prediction that gravity bends light, and shows how that fundamental idea has spawned a rich field of study over the past century. The gravitational deflection of light was first detected by Eddington during a solar eclipse in May 1919, launching Einstein and his theory of relativity into public view. Yet the possibility of using the phenomenon to unlock mysteries of the Universe seemed remote, given the technology of the day. Theoretical work was carried out sporadically over the next six decades, but only with the discovery of the system Q0957+561 in 1979 was gravitational lensing transformed from a curiosity of general relativity into a practical observational tool. This book describes how the three subfields known as strong lensing, weak lensing, and microlensing have grown independently but become increasingly intertwined. Drawing on their research experience, Congdon and Keeton begin with the basic physics of light bending, then present the mathematical foundations of gravitational lensing, building up to current research topics in a clear and systematic way. Relevant background material from physics and mathematics is included, making the book self-contained. The derivations and explanations are supplemented by exercises designed to help students master the theoretical concepts as well as the methods that drive current research. An extensive bibliography guides those wishing to delve more deeply into particular areas of interest. Principles of Gravitational Lensing is ideal for advanced students and seasoned researchers looking to penetrate this thriving subject and even contribute research of their own.







Cosmic Microwave Background Polarization Science and Optical Design of the POLARBEAR and Simons Array Experiments


Book Description

The cosmic microwave background (CMB) radiation contains great amounts of information that allow for studying the physics of the early universe through constraining cosmological parameters in the standard [Lambda]CDM model. The CMB temperature signal has been measured to high precision, but measuring the CMB polarization signal is still in its early stages. The theoretically small primordial CMB polarization B-mode signal has not yet been measured, but has principle importance in that its existence would be strong evidence of inflation. This measurement allows one to probe the earliest state of the universe at energy scales of 10^16 GeV thought to be near the Grand Unified Theory scale. The B-mode signal arising from weak gravitational lensing by large scale structures provides information about the matter composition of the universe and puts strong constraints on the sum of the neutrino masses. This dissertation discusses the optical design, instrumentation, data analysis, and first season science results of the POLARBEAR experiment, a CMB polarization telescope aimed to measure the B-mode signal. The results show the first evidence of non-zero lensing B-modes at sub-degree angular scales on the sky. The development and measurement results of the Fourier transform spectrometer calibration instrument used to characterize the spectral response of the POLARBEAR detectors are also described. The optical design development and systematic studies for the Simons Array, the next generation installment of the experiment, are described as well. The cross polarization effect of Mizuguchi-Dragone breaking due to a prime focus half-wave plate, and the optical redesign of the Simons Array re-imaging optics for increased optical performance at higher frequencies were studied in detail. The Simons Array is planned to fully deploy in 2018 to further study the CMB with enhanced sensitivity.




Constraining Gravitational and Cosmological Parameters with Astrophysical Data


Book Description

We use astrophysical data to shed light on fundamental physics by constraining parametrized theoretical cosmological and gravitational models. Gravitational parameters are those constants that parametrize possible departures from Einstein's general theory of relativity (GR). We develop a general framework to describe torsion in the space time around the Earth, and show that certain observables of the Gravity Probe B (GPB) experiment can be computed in this framework. We examine a toy model showing how a specific theory in this framework can be constrained by GPB data. We also search for viable theories of gravity where the Ricci scalar R in the Lagrangian is replaced by an arbitrary function f(R). Making use of the equivalence between such theories and scalar-tensor gravity, we find that models can be made consistent with solar system constraints either by giving the scalar a high mass or by exploiting the so-called Chameleon Effect. We explore observational constraints from the late-time cosmic acceleration, big bang nucleosynthesis and inflation. Cosmology can successfully describe the evolution of our universe using six or more adjustable cosmological parameters. There is growing interest in using 3-dimensional neutral hydrogen mapping with the redshifted 21 cm line as a cosmological probe. We quantify how the precision with which cosmological parameters can be measured depends on a broad range of assumptions. We present an accurate and robust method for measuring cosmological parameters that exploits the fact that the ionization power spectra are rather smooth functions that can be accurately fit by 7 phenomenological parameters. We find that a future square kilometer array optimized for 21 cm tomography could have great potential, improving the sensitivity to spatial curvature and neutrino masses by up to two orders of magnitude, to k 0.0002 and m 0.007eV, and giving a 4s detection of the spectral index running predicted by the simplest inflation models.




The Cosmic Microwave Background


Book Description

Proceedings of the NATO Advanced Study Institute on the Cosmological Background Radiation, Strasbourg, France, May 27-June 7, 1996