Search Publications

Insights from HST into Ultramassive Galaxies and Early-Universe Cosmology

Kamionkowski, Marc; Muñoz, Julian B.; Sabti, Nashwan

The early-science observations made by the James Webb Space Telescope (JWST) have revealed an excess of ultramassive galaxy candidates that appear to challenge the standard cosmological model (Λ CDM ). Here, we argue that any modifications to Λ CDM that can produce such ultramassive galaxies in the early Universe would also affect the UV galaxy lu…

Joining Bits and Pieces of Reionization History

Finelli, Fabio; Paoletti, Daniela; Hazra, Dhiraj Kumar +1 more

Cosmic microwave background (CMB) temperature and polarization anisotropies from Planck have estimated a lower value of the optical depth to reionization (τ ) compared to WMAP. A significant period in the reionization history would then fall within 6 <redshift(z )<10 , where detection of galaxies with Hubble frontier fields program and indep…

Cosmological Constraints from Multiple Probes in the Dark Energy Survey

Bacon, D.; Bechtol, K.; Challis, P. +161 more

The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy cluster…

Upper Bound of Neutrino Masses from Combined Cosmological Observations and Particle Physics Experiments

Lahav, Ofer; Manera, Marc; Loureiro, Arthur +9 more

We investigate the impact of prior models on the upper bound of the sum of neutrino masses, ∑m_ν . Using data from the large scale structure of galaxies, cosmic microwave background, type Ia supernovae, and big bang nucleosynthesis, we argue that cosmological neutrino mass and hierarchy determination should be pursued using exact models,…

Limits on a Gravitational Field Dependence of the Proton-Electron Mass Ratio from H₂ in White Dwarf Stars

Barstow, M. A.; Bagdonaite, J.; Salumbides, E. J. +4 more

Spectra of molecular hydrogen (H₂) are employed to search for a possible proton-to-electron mass ratio (µ) dependence on gravity. The Lyman transitions of H₂, observed with the Hubble Space Telescope towards white dwarf stars that underwent a gravitational collapse, are compared to accurate laboratory spectra taking int…

Limits on the Dependence of the Fine-Structure Constant on Gravitational Potential from White-Dwarf Spectra

Barstow, M. A.; Holberg, J. B.; Webb, J. K. +5 more

We propose a new probe of the dependence of the fine-structure constant α on a strong gravitational field using metal lines in the spectra of white-dwarf stars. Comparison of laboratory spectra with far-UV astronomical spectra from the white-dwarf star G191-B2B recorded by the Hubble Space Telescope Imaging Spectrograph gives limits of Δα/α=(4.2±1…

Determination of Hyperfine-Induced Transition Rates from Observations of a Planetary Nebula

Judge, Philip G.; Proffitt, Charles R.; Brage, Tomas

Observations of the planetary nebula NGC3918 made with the STIS instrument on the Hubble Space Telescope reveal the first unambiguous detection of a hyperfine-induced transition 2s2p

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