Simon Foreman
A5050403030- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Superconducting and THz Device Technology
- Stellar, planetary, and galactic studies
- Scientific Research and Discoveries
- Gamma-ray bursts and supernovae
- Computational Physics and Python Applications
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Particle physics theoretical and experimental studies
- Astronomical Observations and Instrumentation
- Laser-Matter Interactions and Applications
- Earth Systems and Cosmic Evolution
- Astrophysical Phenomena and Observations
- Leaf Properties and Growth Measurement
- Neutrino Physics Research
- Face and Expression Recognition
- Quantum Mechanics and Applications
- Computer Graphics and Visualization Techniques
- Calibration and Measurement Techniques
Arizona State University
2023-2025
Perimeter Institute
2020-2023
Herzberg Institute of Astrophysics
2020-2023
National Research Council Canada
2021-2023
Massachusetts Institute of Technology
2023
Dominion Astrophysical Observatory
2022
University of Toronto
2018-2020
Canadian Institute for Theoretical Astrophysics
2018-2020
Kavli Institute for Particle Astrophysics and Cosmology
2014-2017
Stanford University
2014-2017
Large scale structure surveys promise to be the next leading probe of cosmological information. It is therefore crucial reliably predict their observables. The Effective Field Theory Scale Structures (EFTofLSS) provides a manifestly convergent perturbation theory for weakly non-linear regime dark matter, where correlation functions are computed in an expansion wavenumber k mode over associated with k_nl. Since most information contained at high wavenumbers, it necessary compute higher order...
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a drift scan radio telescope operating across the 400-800 MHz band. CHIME located at Dominion Radio Astrophysical Observatory near Penticton, BC Canada. instrument designed to map neutral hydrogen over redshift range 0.8 2.5 constrain expansion history of Universe. This goal drives design features instrument. consists four parallel cylindrical reflectors, oriented north-south, each 100 m $\times$ 20 and outfitted with 256 element...
We present a detection of 21-cm emission from large-scale structure (LSS) between redshift 0.78 and 1.43 made with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Radio observations acquired over 102 nights are used to construct maps which foreground filtered stacked on angular spectral locations luminous red galaxies (LRG), line (ELG), quasars (QSO) eBOSS clustering catalogs. find decisive evidence for when stacking all three tracers LSS, logarithm Bayes Factor equal 18.9 10.8...
Given the importance of future large scale structure surveys for delivering new cosmological information, it is crucial to reliably predict their observables. The Effective Field Theory Large Scale Structures (EFTofLSS) provides a manifestly convergent perturbative scheme compute clustering dark matter in weakly nonlinear regime an expansion $k/k_{\rm NL}$, where $k$ wavenumber interest and $k_{\rm NL}$ associated scale. It has been recently shown that EFTofLSS matches $1\%$ level power...
Large scale structure surveys are likely the next leading probe of cosmological information. It is therefore crucial to reliably predict their observables. The Effective Field Theory Scale Structures (EFTofLSS) provides a manifestly convergent perturbation theory for weakly non-linear regime, where dark matter correlation functions computed in an expansion wavenumber k over associated kNL. To push predictions higher wavenumbers, it necessary compute 2-loop power spectrum. For equal-time...
Abstract We present a detailed overview of the science goals and predictions for Prime-Cam direct-detection camera–spectrometer being constructed by CCAT-prime collaboration dedicated use on Fred Young Submillimeter Telescope (FYST). The FYST is wide-field, 6 m aperture submillimeter telescope built (first light in late 2023) an international consortium institutions led Cornell University sited at more than 5600 Cerro Chajnantor northern Chile. one two instruments planned will provide...
This white paper envisions a revolutionary post-DESI, post-LSST dark energy program based on intensity mapping of the redshifted 21cm emission line from neutral hydrogen at radio frequencies. The proposed survey has unique capability to quadruple volume Universe surveyed by optical programs, provide percent-level measurement expansion history $z \sim 6$, open window explore physics beyond concordance $Λ$CDM model, and significantly improve precision standard cosmological parameters. In...
We study the prediction of Effective Field Theory Large Scale Structures (EFTofLSS) for matter power spectrum at different redshifts. In previous work, we found that two-loop can match nonlinear measured from N-body simulations redshift zero within approximately 2% up to k∼ 0.6 h Mpc-1 after fixing a single free parameter, so-called "speed sound". determine time evolution this parameter by matching EFTofLSS simulation output redshifts, and find it is well-described fitting function only...
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Inflation may provide unique insight into the physics at highest available energy scales that cannot be replicated in any realistic terrestrial experiment. Features primordial power spectrum are generically predicted a wide class of models inflation and its alternatives, observationally one most overlooked channels for finding evidence non-minimal inflationary models. Constraints from observations cosmic microwave background cover widest range feature frequencies, but sensitive constraints...
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Abstract We report the detection of 21 cm emission at an average redshift <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>z</mml:mi> </mml:mrow> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>=</mml:mo> <mml:mn>2.3</mml:mn> </mml:math> in cross-correlation data from Canadian Hydrogen Intensity Mapping Experiment (CHIME) with measurements Ly α forest eBOSS. Data collected by CHIME over 88 days 400–500 MHz frequency band (1.8...
We study the prediction of dark matter power spectrum at two-loop order in Effective Field Theory Large Scale Structures (EFTofLSS) using high precision numerical simulations. In our universe, short distance non-linear fluctuations, not under perturbative control, affect long fluctuations through an effective stress tensor that needs to be parametrized terms counterterms are functions fluctuating fields. find it is necessary include three counterterms: a linear term overdensity, δ, quadratic...
The hot dense environment of the early universe is known to have produced large numbers baryons, photons, and neutrinos. These extreme conditions may also other long-lived species, including new light particles (such as axions or sterile neutrinos) gravitational waves. effects any such relics can be observed through their unique imprint in cosmic microwave background (CMB), large-scale structure, primordial element abundances, are important determining initial universe. We argue that future...
The large-scale clustering of matter is impacted by baryonic physics, particularly AGN feedback. Modelling or mitigating this impact will be essential for making full use upcoming measurements cosmic shear and other structure probes. We study effects on the bispectrum, using from a selection state-of-the-art hydrodynamical simulations: IllustrisTNG, Illustris, EAGLE, BAHAMAS. identify low-redshift enhancement peaking at $k\sim 3h\,{\rm Mpc}^{-1}$, that present in several simulations, discuss...
Abstract After reionization, neutral hydrogen (${\rm H\, \small {I}}$) traces the large-scale structure (LSS) of Universe, enabling ${\rm {I}}$ intensity mapping (IM) to capture LSS in 3D and constrain key cosmological parameters. We present a new framework utilizing higher-order cross-correlations study clustering around galaxies, tested using real-space data from IllustrisTNG300 simulation. This approach computes joint distributions k-nearest neighbor (kNN) optical galaxies brightness...
Line-Intensity Mapping is an emerging technique which promises new insights into the evolution of Universe, from star formation at low redshifts to epoch reionization and cosmic dawn. It measures integrated emission atomic molecular spectral lines galaxies intergalactic medium over a broad range frequencies, using instruments with aperture requirements that are greatly relaxed relative surveys for single objects. A coordinated, comprehensive, multi-line intensity-mapping experimental effort...
We investigate the detection prospects for gravitational lensing of three-dimensional maps from upcoming line intensity surveys, focusing in particular on impact nonlinearities standard quadratic estimators. Using perturbation theory, we show that these can provide a significant contaminant to reconstruction, even observations at reionization-era redshifts. However, how this contamination be mitigated with use "bias-hardened" estimator. Along way, present an estimator reconstructing...
The most effective use of data from current and upcoming large scale structure~(LSS) CMB observations requires the ability to predict clustering LSS with very high precision. Effective Field Theory Large Scale Structure (EFTofLSS) provides an instrument for performing analytical computations observables required precision in mildly nonlinear regime. In this paper, we develop efficient implementations these that allow exploration their dependence on cosmological parameters. They are based two...
Wave effects are often neglected in microlensing studies; however, for coherent point-like sources, such as pulsars and fast radio bursts (FRBs), wave will become important their gravitational lensing. In this paper, we describe the optics formalism, its various limits, conditions which these limits hold. Using simple point lens an example, show that frequency dependence of breaks degeneracies present usual geometric limit, constructive interference results larger magnifications further from...
We present the detailed science case, and brief descriptions of telescope design, site, first light instrument plans for a new ultra-wide field submillimeter observatory, CCAT-prime, that we are constructing at 5600 m elevation site on Cerro Chajnantor in northern Chile. Our goals to study star galaxy formation from epoch reionization present, investigate growth structure Universe, improve precision B-mode CMB measurements, interstellar medium Galaxy nearby galaxies through spectroscopic,...
The kinetic Sunyaev-Zeldovich (kSZ) effect will be an important source of cosmological and astrophysical information in upcoming surveys the cosmic microwave background (CMB). However, kSZ also act as dominant noise for several other measurements that use small angular scales CMB temperature maps, since its blackbody nature implies standard component separation techniques cannot used to remove it from observed maps. In this paper, we explore idea "de-kSZing": constructing a template...
We evaluate the potential for current and future cosmic shear measurements from large galaxy surveys to constrain impact of baryonic physics on matter power spectrum. do so using a model-independent parametrization that describes deviations spectrum dark-matter-only case as set principal components are localized in wavenumber redshift. perform forecasts variety data sets, find at least ∼90 per cent constraining these sets is contained no more than nine components. The different can be...
The Cerro Chajnantor Atacama Telescope-prime (CCAT-prime) is a new 6-m, off-axis, low-emissivity, large field-of-view submillimeter telescope scheduled for first light in the last quarter of 2021. In summary, (a) CCAT-prime uniquely combines (up to 8-deg), low emissivity (< 2%) and excellent atmospheric transmission (5600-m site) achieve unprecedented survey capability submillimeter. (b) Over five years, generation science will address physics star formation, galaxy evolution, cluster...
Measurements of gravitational lensing the cosmic microwave background (CMB) hold promise yielding unique insights into cosmology at high redshift. Uncertainties due to baryonic effects associated with galaxy formation and evolution, including gas cooling, star formation, feedback from active galactic nuclei (AGN) supernovae, have typically been neglected when forecasting sensitivity future CMB surveys. In this paper, we determine impact these using four suites hydrodynamical simulations...