A5018384343- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Relativity and Gravitational Theory
- Particle physics theoretical and experimental studies
- Computational Physics and Python Applications
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Geomagnetism and Paleomagnetism Studies
- Neutrino Physics Research
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Theoretical and Computational Physics
- Nonlinear Photonic Systems
- Quantum Chromodynamics and Particle Interactions
- Advanced Differential Geometry Research
- Physics of Superconductivity and Magnetism
- Superconducting and THz Device Technology
Simon Fraser University
2015-2024
University of Portsmouth
2012-2023
National Astronomical Observatories
2020-2023
Laboratoire Univers et Particules de Montpellier
2020
University of Oslo
2014
University of California, San Diego
2013
University of Cambridge
2012-2013
Arizona State University
2013
Institute for Advanced Study
2013
Perimeter Institute
2009-2010
This book lays out the scientific goals to be addressed by next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned consist of dedicated telescopes at South Pole, high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies crossing critical thresholds in search for B-mode polarization signature primordial gravitational waves, determination number...
We study the evolution of linear perturbations in metric $f(R)$ models gravity and identify a potentially observable characteristic scale-dependent pattern behavior cosmological structures. While at background level viable must closely mimic Lambda Cold Dark Matter, differences their prediction for growth large scale structures can be sufficiently to seen with future weak lensing surveys. working Jordan frame, we perform an analytical Einstein demonstrating equivalence dynamics two frames....
We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes physics inflation. focus on prospects for using CMB to differentiate various inflationary mechanisms. In particular, a detection primordial B‐mode would demonstrate that inflation occurred at very high energy scale, and inflaton traversed super‐Planckian distance in field space. explain how such or constraint illuminate aspects Planck scale. Moreover, can constrain scale‐dependence...
The mismatch between the locally measured expansion rate of universe and one inferred from cosmic microwave background measurements by Planck in context standard $\Lambda$CDM, known as Hubble tension, has become most pressing problems cosmology. A large number amendments to $\Lambda$CDM model have been proposed order solve this tension. Many them introduce new physics, such early dark energy, modifications neutrino sector, extra radiation, primordial magnetic fields or varying fundamental...
The standard cosmological model determined from the accurate cosmic microwave background measurements made by Planck satellite implies a value of Hubble constant $H_0$ that is $4.2$ deviations lower than one Type Ia supernovae. best fit also predicts higher values matter density fraction $\Omega_m$ and clustering amplitude $S_8$ compared to those obtained Dark Energy Survey Year 1 data. Here we show accounting for enhanced recombination rate due additional small-scale inhomogeneities in...
We consider predictions for structure formation from modifications to general relativity in which the Einstein-Hilbert action is replaced by a function of Ricci scalar. work without fixing gauge, as well explicit popular coordinate choices, appropriate modification existing cosmological code. present framework comprehensive and practical form that can be directly compared standard perturbation analyses. By considering full evolution equations, we resolve perceived instabilities previously...
In alternative theories of gravity, designed to produce cosmic acceleration at the current epoch, growth large scale structure can be modified. We study potential upcoming and future tomographic surveys such as Dark Energy Survey (DES) Large Synoptic Telescope (LSST), with aid microwave background (CMB) supernovae data, detect departures from expected within general relativity. employ parametric forms quantify time- scale-dependent variation effective gravitational constant differences...
The next generation of weak lensing surveys will trace the growth large scale perturbations through a sequence epochs, offering an opportunity to test general relativity on cosmological scales. We review in detail parametrization used MGCAMB describe modified expected alternative theories gravity and generalized dark energy models. highlight its advantages examine several theoretical aspects. In particular, we show that same set equations can be consistently superhorizon subhorizon linear...
We test general relativity (GR) using current cosmological data: the CMB from WMAP5 [E. Komatsu et al. (WMAP Collaboration), Astrophys. J. Suppl. Ser. 180, 330 (2009)], integrated Sachs-Wolfe (ISW) effect cross correlation of with six galaxy catalogs [T. Giannantonio al., Phys. Rev. D 77, 123520 (2008)], a compilation supernovae (SNe) type Ia including latest Sloan Digital Sky Survey SNe [R. Kessler 185, 32 (2009).], and part weak lensing (WL) data Canada-Franco-Hawaii Telescope Legacy [L....
The next generation of large scale surveys will not only measure cosmological parameters within the framework General Relativity, but also allow for precision tests itself. At order linear perturbations, departures from growth in LCDM model can be quantified terms two functions time and Fourier number k. We argue that local theories gravity, quasi-static approximation, these must ratios polynomials k, with numerator one function being equal to denominator other. Moreover, are even second...
We introduce a patch to the commonly used public codes CAMB and CosmoMC that allows user implement general modification of equations describing growth cosmological perturbations, while preserving covariant conservation energy-momentum. This replaces previously publicly released code MGCAMB, also extending it in several ways. The new version removes limitation late-time-only modifications perturbed Einstein equations, includes parametrizations introduced literature. To demonstrate use patch,...
We apply a new nonparametric Bayesian method for reconstructing the evolution history of equation state w dark energy, based on applying correlated prior w(z), to collection cosmological data. combine latest supernova (SNLS 3 year or Union 2.1), cosmic microwave background, redshift space distortion, and baryonic acoustic oscillation measurements (including BOSS, WiggleZ, 6dF) find that constant appears consistent with current data, but dynamical energy model which evolves from w<-1 at...
We constrain anisotropic cosmic birefringence using four-point correlations of even-parity $E$-mode and odd-parity $B$-mode polarization in the microwave background measurements made by POLARization Background Radiation (POLARBEAR) experiment its first season observations. find that signal from any parity-violating processes is consistent with zero. The Faraday rotation can be compared equivalent quantity generated primordial magnetic fields if they existed. POLARBEAR nondetection translates...
Phenomenological functions $\mathrm{\ensuremath{\Sigma}}$ and $\ensuremath{\mu}$ (also known as ${G}_{\text{light}}/G$ ${G}_{\text{matter}}/G$) are commonly used to parametrize possible modifications of the Poisson equation relating matter density contrast lensing Newtonian potentials, respectively. They will be well constrained by future surveys large-scale structure. But what would implications measuring particular values these for modified gravity theories? We ask this question in context...
The Probe of Inflation and Cosmic Origins (PICO) is a proposed probe-scale space mission consisting an imaging polarimeter operating in frequency bands between 20 800 GHz. We describe the science achievable by PICO, which has sensitivity equivalent to more than 3300 Planck missions, technical implementation, schedule cost.
We present a science forecast for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) survey. Focusing on discrete tracers, we expected accuracy of baryonic acoustic oscillation (BAO), redshift-space distortion (RSD) measurements, fNL parameter quantifying primordial non-Gaussianity, dark energy and modified gravity parameters. also use line-of-sight clustering in Lyman α forest to constrain total neutrino mass. find that eBOSS luminous red galaxies, emission line galaxies quasars...
Constraints on the tension and abundance of cosmic strings depend crucially rate at which they decay into particles gravitational radiation. We study string loops in Abelian-Higgs model by performing field theory simulations loop formation evolution. find that our set emits particle radiation primarily due to kink collisions, time these losses is proportional ${L}^{p}$ with $p\ensuremath{\approx}2$ where $L$ length. In contrast, scales proportion $L$, we conclude emission primary energy loss...
Abstract Recently, in [1], we presented the first combined non-parametric reconstruction of three time-dependent functions that capture departures from standard cosmological model, ΛCDM, expansion history and gravitational effects on matter light currently available combination background large scale structure data. The was performed with without a theory-informed prior, built general Horndeski class scalar-tensor theories, correlates functions. In this work, perform decomposition prior...
Abstract The value of the Hubble constant determined from cosmic microwave background (CMB) and baryonic acoustic oscillation (BAO) measurements is directly dependent on sound horizon at photon–baryon decoupling. There has been significant interest in possibility new physics epoch around recombination that could reduce increase inferred H 0 , thus helping to relieve tension. One way determine if required would be measure BAO CMB without assuming any model for computing horizon. In this...
Overall, brane inflation is compatible with the recent analysis of Wilkinson microwave anisotropy probe (WMAP) data. Here we explore constraints WMAP and 2dF Galaxy Redshift Survey (2dFGRS) data on various inflationary scenarios. Brane naturally ends production cosmic strings, which may provide a way to distinguish these models observationally. We argue that currently available cannot exclude non-negligible contribution from strings definitively. perform partial statistical mixed include...