J. Colin Hill
A5085223087- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Superconducting and THz Device Technology
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Particle physics theoretical and experimental studies
- Advanced Mathematical Theories and Applications
- Pulsars and Gravitational Waves Research
- Relativity and Gravitational Theory
- Adaptive optics and wavefront sensing
- Scientific Research and Discoveries
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Black Holes and Theoretical Physics
- Spectroscopy and Laser Applications
- Astrophysical Phenomena and Observations
- High-Energy Particle Collisions Research
- Spectroscopy and Quantum Chemical Studies
- Mathematics and Applications
Columbia University
2015-2025
Flatiron Health (United States)
2018-2024
Flatiron Institute
2018-2024
Netherlands Institute for Radio Astronomy
2024
Institut d'Astrophysique Spatiale
2024
Université Paris-Saclay
2024
Centre National de la Recherche Scientifique
2024
University of Michigan–Ann Arbor
2023
Institute for Advanced Study
2018-2021
Max Planck Institute for Astronomy
2019
We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from Atacama Cosmology Telescope, using data taken 2013-2016 at 98 150 GHz. The cover more than 17,000 deg$^2$, deepest 600 deg$^2$ with noise levels below 10 $\mu$K-arcmin. use power spectrum derived almost 6,000 these to constrain cosmology. ACT enable a measurement angular scale features in both divergence-like anisotropy, tracing velocity density last-scattering. From one...
We present the science case, reference design, and project plan for Stage-4 ground-based cosmic microwave background experiment CMB-S4.
We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz 218 made by the Atacama Cosmology Telescope (ACT) in three seasons of observations 2008 to 2010. A model primary secondary foreground is fit map power spectra lensing deflection spectrum, including contributions both thermal Sunyaev-Zeldovich (tSZ) effect kinematic (kSZ) effect, Poisson correlated anisotropy unresolved infrared sources, radio correlation between tSZ...
We present the temperature and polarization angular power spectra of CMB measured by Atacama Cosmology Telescope (ACT) from 5400 deg$^2$ 2013-2016 survey, which covers $>$15000 at 98 150 GHz. For this analysis we adopt a blinding strategy to help avoid confirmation bias and, related this, show numerous checks for systematic error done before unblinding. Using likelihood cosmological constrain secondary sources anisotropy foreground emission, derive "CMB-only" spectrum that extends...
The authors provide a thorough study of popular scenario (early dark energy EDE) to alleviate the tension in measurements Hubble constant ${H}_{0}$, which either rely on early Universe probes and cosmological standard model ($\mathrm{\ensuremath{\Lambda}}$CDM) or late through direct, local distant measurements. show that inclusion numerous large-scale structure data is conflict with parameter space lifts ${H}_{0}$ severely limits existence EDE and, thus, makes it very unlikely resolve tension.
BICEP2 has reported the detection of a degree-scale B-mode polarization pattern in Cosmic Microwave Background (CMB) and interpreted measurement as evidence for primordial gravitational waves. Motivated by profound importance discovery waves from early Universe, we examine to what extent combination Galactic foregrounds lensed E-modes could be responsible signal. We reanalyze results show that 100 ×150 GHz 150 data are consistent with cosmology r=0.2 negligible foregrounds, but also r=0...
We present the temperature and polarization angular power spectra measured by Atacama Cosmology Telescope Polarimeter (ACTPol). analyze night-time data collected during 2013-14 using two detector arrays at 149 GHz, from 548 deg$^2$ of sky on celestial equator. use these spectra, with MBAC camera ACT 2008-10, in combination Planck WMAP to estimate cosmological parameters temperature, polarization, temperature-polarization cross-correlations. find new ACTPol be consistent LCDM model. The...
An axion-like field comprising $\sim 10\%$ of the energy density universe near matter-radiation equality is a candidate to resolve Hubble tension; this "early dark energy" (EDE) model. However, as shown in Hill et al. (2020), model fails simultaneously tension and maintain good fit both cosmic microwave background (CMB) large-scale structure (LSS) data. Here, we use redshift-space galaxy clustering data sharpen constraints on EDE We perform first analysis using full-shape power spectrum...
Voyage 2050 White Paper highlighting the unique science opportunities using spectral distortions of cosmic microwave background (CMB). CMB probe many processes throughout history Universe. Precision spectroscopy, possible with existing technology, would provide key tests for expected within cosmological standard model and open an enormous discovery space to new physics. This offers scientific furthering our understanding inflation, recombination, reionization structure formation as well dark...
The early dark energy (EDE) scenario aims to increase the value of Hubble constant (${H}_{0}$) inferred from cosmic microwave background (CMB) data over that found in standard cosmological model ($\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$), via introduction a new form density Universe. EDE component briefly accelerates expansion just prior recombination, which reduces physical size sound horizon imprinted CMB. Previous work has nonzero is not preferred by Planck CMB power spectrum alone,...
Abstract We present tomographic measurements of structure growth using cross-correlations Atacama Cosmology Telescope (ACT) DR6 and Planck cosmic microwave background (CMB) lensing maps with the unWISE Blue Green galaxy samples, which span redshift ranges 0.2 ≲ z 1.1 0.3 1.8, respectively. improve on prior not just by making use new, high-precision ACT maps, but also including additional spectroscopic data for calibration analyzing our a more flexible theoretical model. determine amplitude...
Abstract We present a coherent, re-usable python framework building on the CosmoPower emulator code for high-accuracy calculations of cosmological observables with Einstein-Boltzmann codes. For detailed statistical analyses, such codes require high computing power, making parameter space exploration costly, especially beyond-ΛCDM analyses. Machine learning-enabled emulators are becoming an increasingly popular solution to this problem. To enable generation, sharing and use inference, we...
We report on measurements of the cosmic microwave background (CMB) and celestial polarization at 146 GHz made with Atacama Cosmology Telescope Polarimeter (ACTPol) in its first three months observing. Four regions sky covering a total 270 square degrees were mapped an angular resolution $1.3'$. The map noise levels four are between 11 17 $\mu$K-arcmin. present TT, TE, EE, TB, EB, BB power spectra from these regions. observed E-mode spectrum, displaying six acoustic peaks range...
As galaxy surveys become larger and more complex, keeping track of the completeness, magnitude limit, other survey parameters as a function direction on sky becomes an increasingly challenging computational task. For example, typical angular masks Sloan Digital Sky Survey contain about N=300,000 distinct spherical polygons. Managing with such large numbers polygons intractably slow, particularly for tasks that run in time O(N^2) naive algorithm, finding which overlap each other. Here we...
The kinematic Sunyaev-Zel'dovich (KSZ) effect-the Doppler boosting of cosmic microwave background (CMB) photons due to Compton scattering off free electrons with nonzero bulk velocity-probes the abundance and distribution baryons in Universe. All KSZ measurements date have explicitly required spectroscopic redshifts. Here, we implement a novel estimator for KSZ-large-scale structure cross-correlation based on projected fields: it does not require redshift estimates individual objects,...
We report a measurement of the power spectrum cosmic microwave background (CMB) lensing from two seasons Atacama Cosmology Telescope Polarimeter (ACTPol) CMB data. The is extracted both temperature and polarization data using quadratic estimators. obtain results that are consistent with expectation best-fit Planck LCDM model over range multipoles L=80-2100, an amplitude A_lens = 1.06 +/- 0.15 (stat.) 0.06 (sys.) relative to Planck. Our gives sigma_8 Omega_m^0.25 0.643 0.054; including baryon...
We use microwave temperature maps from two seasons of data the Atacama Cosmology Telescope (ACTPol) at 146 GHz, together with Constant Mass CMASS galaxy sample Baryon Oscillation Spectroscopic Survey to measure kinematic Sunyaev-Ze\v{l}dovich (kSZ) effect over redshift range z = 0.4 - 0.7. positions and continuity equation obtain a reconstruction line-of-sight velocity field. stack cosmic background location each halo, weighted by corresponding reconstructed velocity. The resulting best fit...
Using high-resolution data from the Galactic Arecibo L-Band Feed Array HI (GALFA-Hi) survey, we show that linear structure in neutral hydrogen (Hi) correlates with magnetic field orientation implied by Planck 353 GHz polarized dust emission. The of interstellar medium is more tightly coupled to than previously known. At high latitudes, where are noise dominated, Hi provide an independent constraint on orientation, and hence local polarization angle. We detect strong cross-correlations...
The thermal and kinematic Sunyaev-Zel'dovich effects (tSZ, kSZ) probe the thermodynamic properties of circumgalactic intracluster medium (CGM ICM) galaxies, groups, clusters, since they are proportional, respectively, to integrated electron pressure momentum along line-of-sight. We present constraints on gas thermodynamics CMASS galaxies in Baryon Oscillation Spectroscopic Survey (BOSS) using new measurements kSZ tSZ signals obtained a companion paper. Combining measurements, we measure...
Future high-sensitivity measurements of the cosmic microwave background (CMB) anisotropies and energy spectrum will be limited by our understanding modeling foregrounds. Not only does more information need to gathered combined, but also novel approaches for foregrounds, commensurate with vast improvements in sensitivity, have explored. Here, we study inevitable effects spatial averaging on spectral shapes typical foreground components, introducing a moment approach, which naturally extends...
We construct cosmic microwave background lensing mass maps using data from the 2014 and 2015 seasons of observations with Atacama Cosmology Telescope (ACT). These cover 2100 square degrees sky overlap a wide variety optical surveys. The are signal dominated on large scales have fidelity such that their correlation infrared is clearly visible by eye. also create thermal Sunyaev-Zel'dovich contamination removed novel cleaning procedure only slightly degrades signal-to-noise ratio....
Reconstructed maps of the lensing convergence cosmic microwave background (CMB) will play a major role in precision cosmology coming years. CMB enable calibration masses high-redshift galaxy clusters and yield precise measurements growth structure through cross correlations with surveys. During next decade, reconstruction rely heavily on temperature data, rather than polarization, thus necessitating detailed understanding biases due to extragalactic foregrounds. In near term, most...