A5020522663- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Particle physics theoretical and experimental studies
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Relativity and Gravitational Theory
- Solar and Space Plasma Dynamics
- Computational Physics and Python Applications
- History and Developments in Astronomy
- Earth Systems and Cosmic Evolution
- Epigenetics and DNA Methylation
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Geomagnetism and Paleomagnetism Studies
- Stochastic processes and financial applications
- Prostate Cancer Treatment and Research
- Historical Astronomy and Related Studies
- Cancer-related gene regulation
- Scientific Research and Discoveries
- Seismic Waves and Analysis
Swarthmore College
2016-2025
New York University
2023-2024
The University of Texas at Dallas
2022
University of Bath
2022
MetroHealth
2022
Glaucoma Associates of Texas
2021
Webb Institute
2019
National University of Samoa
2016
Lawrence Berkeley National Laboratory
2012-2013
University of California, Berkeley
2009-2013
Early dark energy (EDE) that behaves like a cosmological constant at early times (redshifts z≳3000) and then dilutes away radiation or faster later can solve the Hubble tension. In these models, sound horizon decoupling is reduced resulting in larger value of parameter H0 inferred from cosmic microwave background (CMB). We consider two physical models for this EDE, one involving an oscillating scalar field another slowly rolling field. perform detailed calculation evolution perturbations...
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...
Using data from the COSMOS survey, we perform first joint analysis of galaxy-galaxy weak lensing, galaxy spatial clustering, and number densities. Carefully accounting for sample variance scatter between stellar halo mass, model all three observables simultaneously using a novel self-consistent theoretical framework. Our results provide strong constraints on shape redshift evolution stellar-to-halo mass relation (SHMR) z=0.2 to z=1. At low find that scales as Mh M*^0.46 this scaling does not...
It has been proposed that cosmic acceleration or inflation can be driven by replacing the Einstein-Hilbert action of general relativity with a function $f(R)$ Ricci scalar $R$. Such gravity theories have shown to equivalent scalar-tensor are incompatible Solar System tests relativity, as long field propagates over scales. Specifically, parameterized post-Newtonian (PPN) parameter in theory is $\ensuremath{\gamma}=1/2$, which far outside range allowed observations. In response flurry papers...
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...
We present a detailed investigation of subdominant oscillating scalar field [``early dark energy'' (EDE)] in the context resolving Hubble tension. Consistent with earlier work, but without relying on fluid approximations, we find that frozen due to friction until ${\mathrm{log}}_{10}({z}_{c})\ensuremath{\sim}3.5$, reaching ${\ensuremath{\rho}}_{\mathrm{EDE}}({z}_{c})/{\ensuremath{\rho}}_{\mathrm{tot}}\ensuremath{\sim}10%$ and diluting faster than matter afterwards, can bring cosmic microwave...
Cosmological observations are used to test for imprints of an ultralight axionlike field (ULA), with a range potentials $V(\ensuremath{\phi})\ensuremath{\propto}[1\ensuremath{-}\mathrm{cos}(\ensuremath{\phi}/f){]}^{n}$ set by the axion-field value $\ensuremath{\phi}$ and decay constant $f$. Scalar dynamics dictate that is initially frozen then begins oscillate around its minimum when Hubble parameter drops below some critical value. For $n=1$, once dynamical, axion energy density dilutes as...
Pulsar timing array (PTA) collaborations in North America, Australia, and Europe, have been exploiting the exquisite precision of millisecond pulsars over decades observations to search for correlated deviations induced by gravitational waves (GWs). PTAs are sensitive frequency band ranging just below 1 nanohertz a few tens microhertz. The discovery space this is potentially rich with populations inspiraling supermassive black-holes binaries, decaying cosmic string networks, relic...
Quantum fluctuations of the gravitational field in early Universe, amplified by inflation, produce a primordial gravitational-wave background across broad frequency band. We derive constraints on spectrum this radiation, and hence theories combining experiments that cover 29 orders magnitude frequency. These include Planck observations cosmic microwave temperature polarization power spectra lensing, together with baryon acoustic oscillations big bang nucleosynthesis measurements, as well new...
We revisit the impact of early dark energy (EDE) on galaxy clustering using BOSS power spectra, analyzed effective field theory (EFT) large-scale structure (LSS) and anisotropies cosmic microwave background (CMB) from Planck. Recent studies found that these data place stringent constraints maximum abundance EDE allowed in Universe. argue here their conclusions are a consequence choice priors parameter space, rather than any disagreement between model. For example, when considering EFT-LSS,...
We investigate constraints on early dark energy (EDE) using ACT DR4, SPT-3G 2018, Planck polarization, and restricted temperature data (at $\ensuremath{\ell}<650$), finding a $3.3\ensuremath{\sigma}$ preference ($\mathrm{\ensuremath{\Delta}}{\ensuremath{\chi}}^{2}=\ensuremath{-}16.2$ for three additional degrees of freedom) EDE over $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$. The contributes maximum fractional density ${f}_{\mathrm{EDE}}({z}_{c})=0.16{3}_{\ensuremath{-}0.04}^{+0.047}$ at...
Analyses of the full shape BOSS DR12 power spectrum using one-loop prediction from Effective Field Theory Large-Scale Structure (EFTBOSS) have led to new constraints on extensions $\Lambda$CDM model, such as Early Dark Energy (EDE) which has been suggested a resolution "Hubble tension". In this paper, we re-assess constraining EFTBOSS EDE in light correction normalization window functions. Overall find that are weakened, and represent small change compared Planck conventional BAO/$f\sigma_8$...
We assess the robustness of $\Lambda$CDM results from full-shape analysis BOSS power spectrum using one-loop prediction Effective Field Theory Large-Scale Structure (EFTofLSS). The public likelihoods PyBird and CLASS-PT lead to in agreement only at $1\sigma$ level, despite fact that they are derived same dataset theory model. perform a thorough comparison various analyses choices made between two pipelines, identify differences come choice prior on EFT parameters, dubbed "West-coast" (WC)...
Shortly after the addition of a $1/R$ term to Einstein-Hilbert action was proposed as solution cosmic-acceleration puzzle, Chiba showed that such theory violates Solar System tests gravity. A flurry recent papers have called Chiba's result into question. They argue spherically-symmetric vacuum spacetime in this is Schwarzschild-de Sitter solution, making consistent with tests. We point out although exists theory, it not unique and describes System. The correctly matches onto stellar-interior...
Primordial gravitational waves (GWs) with frequencies > or approximately equal to 10(-15) Hz contribute the radiation density of Universe at time decoupling cosmic microwave background (CMB). This affects CMB and matter power spectra in a manner identical massless neutrinos, unless initial perturbation for GWs is nonadiabatic, as may occur if such are produced during inflation some post-inflation phase transition. In either case, current observations provide constraint GW amplitude that...
Inflation generically predicts a stochastic background of gravitational waves over broad range frequencies, from those accessible with cosmic microwave (CMB) measurements, to directly gravitational-wave detectors, like NASA's Big-Bang Observer (BBO) or Japan's Deci-Hertz Interferometer Gravitational-wave (DECIGO), both currently under study. Here we investigate the detectability inflationary at BBO/DECIGO frequencies. To do so, survey slow-roll models consistent constraints CMB and...
We have studied a sample of 809 Mg II absorption systems with 1.0 < z_abs 1.86 in the spectra SDSS QSOs, aim understanding nature and abundance dust chemical abundances intervening absorbers. Normalized, composite were derived, for measurements, full several sub-samples, chosen on basis line strengths other absorber QSO properties. Average extinction curves obtained sub-samples by comparing their geometric mean those matching samples QSOs without absorbers spectra. There is clear evidence...
Deviations from general relativity, such as could be responsible for the cosmic acceleration, would influence growth of large-scale structure and deflection light by that structure. We clarify relations between several different model-independent approaches to deviations relativity appearing in literature, devising a translation table. examine current constraints on deviations, using weak gravitational lensing data CFHTLS COSMOS surveys, microwave background radiation WMAP5, supernova...
One of the possible low-energy consequences string theory is addition a Chern-Simons term to standard Einstein-Hilbert action general relativity. It can be argued that quintessence field should couple this term, and if so, it drives in linearized parity-violating interaction between gravito-electric gravitomagnetic fields. In paper, spacetime for gravity around massive spinning body found include new modifications have not appeared previous work. The orbits test bodies precession gyroscopes...