A5035662185- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Black Holes and Theoretical Physics
- Astronomical Observations and Instrumentation
- Superconducting and THz Device Technology
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Relativity and Gravitational Theory
- Solar and Space Plasma Dynamics
- Experimental and Theoretical Physics Studies
- Blind Source Separation Techniques
- Algorithms and Data Compression
- CCD and CMOS Imaging Sensors
- Advanced Computational Techniques and Applications
- Astrophysical Phenomena and Observations
- Precipitation Measurement and Analysis
- Satellite Image Processing and Photogrammetry
- History and Developments in Astronomy
- Statistical and numerical algorithms
Queen Mary University of London
2021-2024
University of Manchester
2018-2024
Université Toulouse III - Paul Sabatier
2021
Centre National de la Recherche Scientifique
2021
Czech Academy of Sciences, Institute of Physics
2021
Czech Academy of Sciences
2021
Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères
2021
Université Paris Sciences et Lettres
2021
Sorbonne Université
2021
Université de Toulouse
2021
Las Cumbres Observatory Global Telescope (LCOGT) is a young organization dedicated to time-domain observations at optical and (potentially) near-IR wavelengths. To this end, LCOGT constructing worldwide network of telescopes, including the two 2 m Faulkes as many 17 × 1 23 40 cm telescopes. These telescopes initially will be outfitted for imaging (excepting telescopes) spectroscopy wavelengths between atmospheric UV cutoff roughly 1-μm limit silicon detectors. Since first LCOGT's are now...
We present the first calculation of an intrinsically relativistic quantity, leading-order correction to Newtonian theory, in fully nonlinear cosmological large-scale structure studies. Traditionally, formation standard $\mathrm{\ensuremath{\Lambda}}\text{CDM}$ cosmology is studied using N-body simulations, based on gravitational dynamics expanding background. When one derives regime a way that consistent approximation Einstein equations, usual scalar potential gravitomagnetic vector...
Cold dark matter is a crucial constituent of the current concordance cosmological model. Having vanishing equation state (EOS), its energy density scales with inverse cosmic volume and thus uniquely described by single number, present abundance. We test law for (DM) allowing EOS to vary independently in eight redshift bins range $z={10}^{5}$ $z=0$. use latest measurements microwave background radiation from Planck satellite supplement them baryon acoustic oscillation (BAO) data 6dF SDSS-III...
We examine how the properties of dark matter, parameterised by an equation state parameter $w$ and two perturbative Generalised Dark Matter (GDM) parameters $c^2_s$ (the sound speed) $c^2_\text{vis}$ viscosity), are constrained existing cosmological data, particularly Planck 2015 data release. find that GDM consistent with zero, strongly constrained, showing no evidence for extending matter model beyond Cold (CDM) paradigm. The is to be within $-0.000896<w<0.00238$ at $99.7\%$ confidence...
We perform the first test of dark matter (DM) stress-energy evolution through cosmic history, using microwave background measurements supplemented with baryon acoustic oscillation data and Hubble Space Telescope key project data. constrain DM equation state (EoS) in 8 redshift bins, its sound speed (shear) viscosity 9 finding no convincing evidence for non-$\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ values any bins. Despite this enlarged parameter space, are constrained relatively well at...
The Cold Dark Matter (CDM) model, wherein the dark matter is treated as a pressureless perfect fluid, provides good fit to galactic and cosmological data. With advent of precision cosmology, it should be asked whether this simplest model needs extended, doing so could improve our understanding properties matter. One established parameterisation for generalising CDM fluid Generalised (GDM) in which an imperfect with pressure shear viscosity that fulfill certain closure equations. We...
Abstract Stage-IV large scale structure surveys are promising probes of gravity on cosmological scales. Due to the vast model-space in modified literature, model-independent parameterisations represent useful and scalable ways test extensions ΛCDM. In this work we use a recently validated approach computing non-linear 3 × 2 pt observables models with time-varying effective gravitational constant μ slip η that is binned redshift produce Fisher forecasts for an LSST Y10-like survey. We also...
Newtonian simulations are routinely used to examine the matter dynamics on non-linear scales. However, even these scales, gravity is not a complete description of gravitational effects. A post-Friedmann approach shows that leading-order correction theory vector potential in metric. This can be calculated from N-body simulations, requiring method for extracting velocity field. Here, we present full details our calculation potential, using Delaunay Tessellation Field Estimator code. We include...
New telescopes are being built to measure the Cosmic Microwave Background (CMB) with unprecedented sensitivity, including Simons Observatory (SO), CCAT-prime, BICEP Array, SPT-3G, and CMB Stage-4. We present observing strategies for located in Chile that informed by tools used develop recent Atacama Cosmology Telescope (ACT) Polarbear surveys. As ACT Polarbear, these composed of scans sweep azimuth at constant elevation. explore both small (0.42 m) aperture (SAT) a large (6 telescope (LAT)....
In this paper we examine cosmological weak lensing on non-linear scales and show that there are Newtonian relativistic contributions the latter can also be extracted from standard simulations. We use post-Friedmann formalism, a post-Newtonian type framework for cosmology, to derive full weak-lensing deflection angle valid any metric theory of gravity. only contributing term is quadratic in first order expected Born correction lens-lens coupling term. analyse vector tensor E- B- mode cosmic...
Vector perturbations sourced by topological defects can generate rotations in the lensing of background galaxies. This is a potential smoking gun for existence since rotation generates curl-like component weak signal which not generated standard density at linear order. calculated as cosmic strings. Future large scale surveys should be able to detect this even string tensions an order magnitude lower than current constraints.
Weak lensing has become an increasingly important tool in cosmology and the use of galaxy shapes to measure cosmic shear routine. The weak-lensing distortion tensor contains two other effects addition components shear: convergence rotation. rotation mode is not measurable using standard estimators based on shapes, as there no information original images before they were lensed. Due this, estimator been proposed for cosmological surveys, never constrained. Here, we derive this quantity, which...
This paper studies model independent modified gravity in cosmological settings. Using higher order equations from the post Friedmann approach to derive a single set of ``simple 1PF'' (first Friedmann) equations, author looks at both traditional limits gravity, large scales where relativistic perturbation theory works and smaller nonlinear that are domain Newtonian gravity. Criteria provided for deciding which theories amenable proposed rigorous underpinning phenomenological N-body...
The CMB $B$-mode polarisation signal -- both the primordial gravitational wave signature and sourced by lensing is subject to many contaminants from systematic effects. Of particular concern are systematics that result in mixing of signals different ``spin'', particularly leakage much larger spin-0 intensity spin-2 signal. We present a general formalism, which can be applied arbitrary focal plane setups, characterises terms their spin. provide expressions describe how spin-coupled observed...
In this paper we examine cosmological weak lensing on non-linear scales and show that there are Newtonian relativistic contributions the latter can also be extracted from standard simulations. We use post-Friedmann formalism, a post-Newtonian type framework for cosmology, to derive full weak-lensing deflection angle valid any metric theory of gravity. only contributing term is quadratic in first order expected Born correction lens-lens coupling term. analyse vector tensor E- B- mode cosmic...
We describe an initiative to build and use the Dark Energy Spectrometer (DESpec), a wide-field spectroscopic survey instrument for Blanco 4 meter telescope at Cerro Tololo InterAmerican Observatory (CTIO) in Chile. A new system with about 4000 robotically positioned optical fibers will be interchangeable CCD imager of existing Camera (DECam), accessing field view 3.8 square degrees single exposure. The proposed operated by CTIO available astronomy community. Our collaboration proposes DESpec...
In this proceeding, we present studies of instrumental systematic effects for the Simons Obsevatory (SO) that are associated with detector system and its interaction full SO experimental systems. will measure Cosmic Microwave Background (CMB) temperature polarization anisotropies over a wide range angular scales in six bands bandcenters spanning from 27 GHz to 270 GHz. We explore including intensity-to-polarization leakage due coupling optics, bolometer nonlinearity, uncalibrated gain...
Model-independent parametrisations of modified gravity have attracted a lot attention over the past few years and numerous combinations experiments observables been suggested to constrain parameters used in these models. Galaxy clusters mentioned, but not looked at as extensively literature some other probes. Here we look adding galaxy into mix examine how they could improve constraints on parameters. In particular, forecast from combining Planck satellite Cosmic Microwave Background (CMB)...
Recently, an extension to the parametrized post-Newtonian (PPN) formalism has been proposed. This formalism, post-Newtonian-Vainshteinian (PPNV) is well suited theories which exhibit Vainshtein screening of scalar fields. In this paper we apply PPNV quartic and quintic Galileon for first time. As simple generalizations standard scalar-tensor field they are important guides generalization approaches effects gravity beyond general relativity. case, find new potentials both screened unscreened...
Constraints on the properties of cosmological dark matter have previously been obtained in a model-independent fashion using Generalised Dark Matter (GDM) framework. Here we extend that work several directions: We consider inclusion WiggleZ power spectrum data, and show this improves constraints two perturbative GDM parameters, $c^2_s$ $c^2_\text{vis}$, by factor 3, for conservative choice wavenumber range. A less can yield an improvement up to order magnitude compared previous constraints....
We describe the first results on weak gravitational lensing from SuperCLASS survey: survey specifically designed to measure effect in radio-wavelength data, both alone and cross-correlation with optical data. analyse 1.53 square degrees of data Subaru telescope 0.26 radio e-MERLIN VLA telescopes (the DR1 set). Using standard methodologies only we make a significant (10 sigma) detection signal (a shear power spectrum) due massive supercluster galaxies targeted region. For develop new method...
Many modified gravity theories are under consideration in cosmology as the source of accelerated expansion universe and linear perturbation theory, valid on largest scales, has been examined many these models. However, smaller non-linear scales offer a richer phenomenology with which to constrain theories. Here, we consider Hu-Sawicki form f(R) apply post-Friedmann approach derive leading order equations for i.e. Newtonian-like regime. We reproduce standard scalar field, gravitational slip...
Abstract General relativity manifests very similar equations in different regimes, notably large scale cosmological perturbation theory, non-linear structure formation, and weak field galactic dynamics. The same is not necessarily true alternative gravity theories, particular those that possess MONDian behaviour (“relativistic extensions” of MOND). In these theories regimes are typically studied quite separately, sometimes even with the freedom chosen differently regimes. If we wish to...
We present approaches to quickly simulate systematics affecting CMB observations, including the effects of scanning strategy. Using summary properties scan we capture features full time ordered data (TOD) simulations, allowing maps and power spectra be generated at much improved speed for a number - cases experienced ups 3-4 orders magnitude when implementing map-based approaches. demonstrate effectiveness capturing salient by directly comparing TOD simulations seeing agreement sub-percent...
Future CMB experiments will require exquisite control of systematics in order to constrain the $B$-mode polarisation power spectrum. One class that requires careful study is instrumental systematics. The potential impact such most readily understood by considering analysis pipelines based on pair differencing. In this case, any differential gain, pointing or beam ellipticity between two detectors a can result intensity leakage into spectrum, which needs be controlled high precision due much...