37 citations · 84 across the 14 of their papers we have counts for
14 papers
Searching for new physics using high precision absorption spectroscopy; continuum placement uncertainties and the fine structure constant in strong gravity
Chung-Chi Lee, John K. Webb, Darren Dougan +3
Searches for variations of fundamental constants require a comprehensive understanding of measurement errors. This paper examines a source of error that is usually overlooked: the…
Searching for new physics using high precision absorption spectroscopy; continuum placement uncertainties and towards the quasar PHL957
John K. Webb, Chung-Chi Lee, Dinko Milaković +3
Detecting or placing upper limits on spacetime variations of fundamental constants requires quantifying every potential source of uncertainty. We continue our previous study into t…
Isotopic abundance of carbon in the DLA towards QSO B1331+170
Dinko Milaković, John K. Webb, Paolo Molaro +19
Chemical evolution models predict a gradual build-up of C in the universe, based on empirical nuclear reaction rates and assumptions on the properties of stellar populations…
The Mystery of Alpha and the Isotopes
John K. Webb, Chung-Chi Lee, Dinko Milakovic +3
We report unbiased AI measurements of the fine structure constant in two proximate absorption regions in the spectrum of the quasar HE05154414. The data are high resolution,…
Convergence properties of fine structure constant measurements using quasar absorption systems
John K. Webb, Chung-Chi Lee
Searches for spacetime variations of fundamental constants have entered an era of unprecedented precision. New, high quality quasar spectra require increasingly refined analytic me…
Methods for quasar absorption system measurements of the fine structure constant in the 2020s and beyond
Dinko Milaković, Chung-Chi Lee, Paolo Molaro +1
This article reviews the two major recent developments that significantly improved cosmological measurements of fundamental constants derived from high resolution quasar spectrosco…
Varying alpha, blinding, and bias in existing measurements
Chung-Chi Lee, John K. Webb, Robert F. Carswell +3
The high resolution spectrograph ESPRESSO on the VLT allows measurements of fundamental constants at unprecedented precision and hence enables tests for spacetime variations predic…
Measuring the fine structure constant on white dwarf surfaces; uncertainties from continuum placement variations
Chung-Chi Lee, John K. Webb, Darren Dougan +2
Searches for variations of fundamental constants require accurate measurement errors. There are several potential sources of errors and quantifying each one accurately is essential…
Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies
Elcio Abdalla, Guillermo Franco Abellán, Amin Aboubrahim +200
In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological…
Avoiding bias in measurements of fundamental constants from high resolution quasar spectra
John K. Webb, Chung-Chi Lee, Dinko Milaković
Recent advances in spectroscopic instrumentation and calibration methods dramatically improve the quality of quasar spectra. Supercomputer calculations show that, at high spectral…
Addendum: Precision in high resolution absorption line modelling, analytic Voigt derivatives, and optimisation methods
Chung-Chi Lee, John K. Webb, Robert F. Carswell
The parent paper to this Addendum describes the optimisation theory on which VPFIT, a non-linear least-squares program for modelling absorption spectra, is based. In that paper, we…
Precision in high resolution absorption line modelling, analytic Voigt derivatives, and optimisation methods
John K. Webb, Robert F. Carswell, Chung-Chi Lee
This paper describes the optimisation theory on which VPFIT, a non-linear least-squares program for modelling absorption spectra, is based. Particular attention is paid to precisio…
Four direct measurements of the fine-structure constant 13 billion years ago
Michael R. Wilczynska, John K. Webb, Matthew Bainbridge +14
Observations of the redshift z=7.085 quasar J1120+0641 have been used to search for variations of the fine structure constant, alpha, over the redshift range 5.5 to 7.1. Observatio…
A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455-282, WD0621-376, and WD2211-495
S. P. Preval, M. A. Barstow, M. Bainbridge +7
Using newly obtained high-resolution data () from the \textit{Hubble Space Telescope}, and archival UV data from the \textit{Far Ultraviolet Spectroscopic E…