A5027817737- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Scientific Research and Discoveries
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Plant Water Relations and Carbon Dynamics
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Remote Sensing in Agriculture
- Bayesian Methods and Mixture Models
- Advanced Clustering Algorithms Research
- Combustion and flame dynamics
- demographic modeling and climate adaptation
- Magnetic confinement fusion research
- Advanced Vision and Imaging
- Adaptive optics and wavefront sensing
- Impact of Light on Environment and Health
- Leaf Properties and Growth Measurement
- Tree-ring climate responses
- Control and Dynamics of Mobile Robots
University of Edinburgh
2016-2025
Royal Observatory
2015-2024
UK Astronomy Technology Centre
2023-2024
Scottish Universities Physics Alliance
2018-2022
Durham University
2009-2017
Indiana Cancer Consortium
2014
Pontificia Universidad Católica de Chile
2014
University of Pennsylvania
2010-2013
Purple Mountain Observatory
2007-2008
Chinese Academy of Sciences
2007-2008
DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with wide-area galaxy quasar redshift survey. To trace underlying matter distribution, spectroscopic targets be selected in four classes from imaging data. We measure luminous red galaxies up to $z=1.0$. probe Universe out even higher redshift, target bright [O II] emission line $z=1.7$....
DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with wide-area galaxy quasar redshift survey. The instrument robotically-actuated, fiber-fed spectrograph capable taking up to 5,000 simultaneous spectra over wavelength range from 360 nm 980 nm. fibers feed ten three-arm spectrographs resolution $R= λ/Δλ$ between 2000 5500, depending on...
We explore voids in dark matter and halo fields from simulations of Λ cold Hu–Sawicki f (R) models. In gravity, void abundances are greater than that general relativity (GR). Differences for much smaller, but still at the 2σ, 6σ 14σ level model parameter |fR0| = 10−6, 10−5 10−4. Counter-intuitively, abundance large found using haloes gravity is lower, which suggests not necessarily emptier galaxies this model. find number density profiles distinguishable GR, same gravity. This can be...
We investigate the behavior of fifth force in voids chameleon models using spherical collapse method. Contrary to Newtonian gravity, we find is repulsive voids. The strength depends on density inside and outside void region as well its radius. It can be many times larger than their ratio principle unbound. This very different from case halos, where no more 1/3 gravity. evolution governed by effective dark energy force. While first two forces are common both LCDM universes, unique latter....
Observations of galaxies and galaxy clusters in the local universe can account for only ∼10% total baryon content. Cosmological simulations predict that “missing baryons” are spread throughout filamentary structures cosmic web, forming a low-density gas with temperatures 10 5 −10 7 K. We search this warm-hot intergalactic medium (WHIM) by stacking Planck Compton y -parameter map thermal Sunyaev-Zel’dovich (tSZ) effect 1 002 334 pairs CMASS from Sloan Digital Sky Survey. model contribution...
We present a systematic comparison of several existing and new void-finding algorithms, focusing on their potential power to test particular class modified gravity models – chameleon f(R) gravity. These deviate from standard general relativity (GR) more strongly in low-density regions thus voids are promising venue them. use halo occupation distribution (HOD) prescriptions populate haloes with galaxies, tune the HOD parameters such that galaxy two-point correlation functions same both GR...
We have derived estimators for the linear growth rate of density fluctuations using cross-correlation function (CCF) voids and haloes in redshift space. In theory, this CCF contains only monopole quadrupole terms. At scales greater than void radius, theory is a good match to traced out by haloes; small-scale random velocities are unimportant at these radii, tending cause small often negligible elongation near its origin. By extracting from CCF, we measure without prior knowledge profile or...
ABSTRACT The dependence of galaxy clustering on local density provides an effective method for extracting non-Gaussian information from surveys. two-point correlation function (2PCF) a complete statistical description Gaussian field. However, the late-time field becomes due to non-linear gravitational evolution and higher-order summary statistics are required capture all its cosmological information. Using Fisher formalism based halo catalogues Quijote simulations, we explore possibility...
ABSTRACT We present a clustering analysis of the BOSS DR12 CMASS galaxy sample, combining measurements two-point correlation function and density-split down to scale $1 \, h^{-1}\, \text{Mpc}$. Our theoretical framework is based on emulators trained high-fidelity mock catalogues that forward model cosmological dependence statistics within an extended-ΛCDM framework, including redshift-space Alcock–Paczynski distortions. base-ΛCDM finds ωcdm = 0.1201 ± 0.0022, σ8 0.792 0.034, ns 0.970 0.018,...
We measure the average temperature decrement on cosmic microwave background (CMB) produced by voids selected in Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z 0.44. find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat filter scaled to radius of each void, we assess statistical significance at ∼2σ, make crucial use N-body simulations calibrate our analysis. As expected, that large produce cold spots...
We use data from the DESI Legacy Survey imaging to probe galaxy density field in tomographic slices covering redshift range $0<z<0.8$. After careful consideration of completeness corrections and galactic cuts, we obtain a sample $4.9\times 10^7$ galaxies 17 739 deg$^2$. derive photometric redshifts with precision $\sigma_z/(1+z)=0.012 - 0.015$, compare alternative estimates. Cross-correlation maps Planck CMB temperature lensing convergence growth structure since $z=0.8$. The signals are...
We present a public suite of weak-lensing mock data, extending the Scinet Light Cone Simulations (SLICS) to simulate cross-correlation analyses with different cosmological probes. These mocks include Kilo Degree Survey (KiDS)-450- and LSST-like lensing cosmic microwave background maps simulated spectroscopic surveys that emulate Galaxy And Mass Assembly, BOSS, 2-degree Field Lensing galaxy surveys. With 844 independent realizations, our are optimized for combined-probe covariance estimation,...
We study cosmic voids in the normal-branch Dvali-Gabadadze-Porrati (nDGP) braneworld models, which are representative of a class modified gravity theories where deviations from General Relativity usually hidden by Vainshtein screening high-density environments. This is less efficient away these environments, makes ideally suited for testing this models. use N-body simulations $\Lambda$-cold dark matter ($\Lambda$CDM) and nGDP universes, haloes populated with mock galaxies that mimic...
Abstract Shortly after its discovery, General Relativity (GR) was applied to predict the behavior of our Universe on largest scales, and later became foundation modern cosmology. Its validity has been verified a range scales environments from Solar system merging black holes. However, experimental confirmations GR cosmological have so far lacked accuracy one would hope for — applications those being largely based extrapolation there sometimes questioned in shadow discovery unexpected cosmic...
ABSTRACT Accurate modelling of redshift-space distortions (RSD) is challenging in the non-linear regime for two-point statistics e.g. correlation function (2PCF). We take a different perspective to split galaxy density field according local density, and cross-correlate those densities with entire field. Using mock galaxies, we demonstrate that combining series cross-correlation functions (CCFs) offers improvements over 2PCF as follows: (1) The distribution peculiar velocities each nearly...
ABSTRACT We present a large suite of cosmological simulations, the forge (F-of-R Gravity Emulator) simulation suite, which is designed to build accurate emulators for observables in galaxy clustering, weak gravitational lensing, and clusters f(R)-gravity model. A total 200 simulations explore parameter space around standard Planck cosmology with Latin hypercube, 50 combinations $\bar{f}_{R0}$, Ωm, σ8, h all other parameters fixed. For each combination, or node, we ran four independent one...
We present a new method for constructing maps of the secondary temperature fluctuations imprinted on cosmic microwave background (CMB) radiation by photons propagating through evolving gravitational potential. Large cosmological N-body simulations are used to calculate complete non-linear evolution peculiar Tracing light rays back past cone chosen observer accurately captures perturbations generated linear (the integrated Sachs–Wolfe or ISW effect) and Rees–Sciama RS evolution. These effects...
We study projected underdensities in the cosmic galaxy density field known as 'troughs', and their overdense counterparts, which we call 'ridges'. identify these regions using a bright sample of foreground galaxies from photometric Kilo-Degree Survey (KiDS), specifically selected to mimic spectroscopic Galaxy And Mass Assembly survey (GAMA). Using background KiDS, measure weak gravitational lensing profiles troughs/ridges. quantify amplitude strength $A$ function percentile rank $P$...
We study the late-time Integrated Sachs-Wolfe (ISW) effect in $f(R)$ gravity using N-body simulations. In model under study, linear growth rate is larger than that general relativity (GR). This slows down decay of cosmic potential and induces a smaller ISW on large scales. Therefore, $\dot\Phi$ (time derivative potential) power spectrum at $k<0.1h$/Mpc suppressed relative to GR. non-linear regime, relatively rapid structure formation boosts GR, $k>0.1h$/Mpc increased (100$\%$ greater small...
We have searched for the signature of cosmic voids in CMB, both Planck temperature and lensing-convergence maps; should give decrements both. use zobov from DR12 SDSS CMASS galaxy sample. base our analysis on N-body simulations, to avoid a posteriori bias. For first time, we detect CMB lensing: significance is $3.2\sigma$, close $\Lambda$CDM amplitude projected density-profile shape. A dip also seen, at modest ($2.3\sigma$), with about 6 times prediction. This signal induced mostly by radius...
Cosmic voids, the less dense patches of Universe, are promising laboratories to extract cosmological information. Thanks their unique low density character, voids extremely sensitive diffuse components such as neutrinos and dark energy, represent ideal environments study modifications gravity, where effects expected be more prominent. Robust void-related observables, including for example redshift-space distortions (RSD) weak lensing around a way chase test new physics. Cosmological analysis...
We quantify the cosmological constraining power of `lensing PDF' - one-point probability density weak lensing convergence maps by modelling this statistic numerically with an emulator trained on $w$CDM cosmic shear simulations. After validating our methods Gaussian and lognormal fields, we show that `multi-scale' PDFs measured from multiple levels smoothing offer considerable gains over two-point statistics, owing to their ability extract non-Gaussian information: for a mock Stage-III...
ABSTRACT Combining galaxy clustering information from regions of different environmental densities can help break cosmological parameter degeneracies and access non-Gaussian the density field that is not readily captured by standard two-point correlation function (2PCF) analyses. However, modelling these density-dependent statistics down to non-linear regime has so far remained challenging. We present a simulation-based model able capture dependence full shape density-split (DSC) intra-halo...
We revisit the excursion set approach to calculate void abundances in chameleon-type modified gravity theories, which was previously studied by Clampitt, Cai & Li. focus on properly accounting for void-in-cloud effect, i.e. growth of those voids sitting overdense regions may be restricted evolution their surroundings. This effect change distribution function hence affect predictions differences between (MG) and general relativity (GR). show that thin-shell approximation usually used fifth...
We report the results of 2dF-VST ATLAS Cold Spot galaxy redshift survey (2CSz) based on imaging from VST and spectroscopy 2dF AAOmega over core CMB Spot. sparsely surveyed inner 5° radius to a limit iAB ≤ 19.2, sampling ∼7000 galaxies at z < 0.4. have found voids = 0.14, 0.26 0.30 but they are interspersed with small overdensities, scale these is insufficient explain through ΛCDM ISW effect. Combining previous data out ∼ 1, we conclude that could not been imprinted by void confined...