Skip to Main content

Rachael Beaton, Ph.D.

Presentation Title

21st Century Cosmological Tensions that have Emerged from Precision Measurements from Space Telescopes

Presentation Description

In the past decade, a number of tensions have arisen between observational data in the nearby universe and the standard cosmological model, Lambda-Cold Dark Matter (LCDM) resulting from fits to anisotropies in the Cosmic Microwave Background.

Two primary tensions are present:

  1. A tension in the value of the Hubble Constant (the current expansion rate of the universe)
  2. A tension in the sigma-8 parameter (the local clustering of matter at 8 Mpc scales)

In both cases, the tensions are well-constrained by multiple independent measurements produced by multiple teams using multiple datasets from ground and space.

In this presentation, Beaton will introduce these tensions, focusing on the current observational data and the unique space-based instrumentation that enabled them. She will highlight some of the puzzles that the two tensions pose for constructing theoretical cosmological models, and the insights into the dark sector that could be gained by resolving the tensions.

As will be apparent in the presentation, the key to obtaining astrophysical measurements at this level of precision has been the use of space-based instrumentation – whether to measure the Cosmic Microwave Background with COBE or WMAP, or to use standard candles to measure distances with the Hubble Space Telescope and now the James Webb Space Telescope. Thus, Beaton will conclude by looking to the future of cosmological measurements enabled by the Nancy Grace Roman Space Telescope and mention ways to get involved in its transformative science.


Dr. Rachael Beaton joined the Science Operations Center for the Nancy Grace Roman Space Telescope in 2022, where she co-leads RDox, the Roman Documentation system, and the analysis of ground testing data for the Wide Field Instrument. Prior to this, she was a Carnegie-Princeton Fellow, a Hubble Fellow at Princeton University (2017-22) and a postdoctoral research associate at the Observatories of the Carnegie Institution for Science (2014-17) after receiving her Ph.D. in 2014 from the University of Virginia. Her doctoral dissertation was recognized with the 2016 Robert C. Trumpler Award. She was a member of the Carnegie-Chicago Hubble Program to measure the Hubble constant and was a participant in the SDSS-IV APOGEE-2 to map the Milky Way Galaxy.

Portrait of Rachael Beaton Beaton is an observational astronomer who uses the resolved and semi-resolved stellar populations to understand properties of galaxies in the nearby universe. In particular, she is interested in measuring precise distances to the hosts of supernova and in securing the foundation of the distance scale locally with observations of stars in the Milky Way and Large Magellanic Clouds. For this work, she combines inferences from photometry and spectroscopy from ground and space.

Beaton served as the Science Working Group chair of the Apache Point Galactic Evolution Experiment (APOGEE) in SDSS-IV from 2017 to the conclusion of the project in 2022. She also served as co-chair of the Committee on Inclusiveness in SDSS-IV (COINS) from 2018-22, and served on the transition team to SDSS-V. Beaton joined the Board of the Astronomical Society of the Pacific in 2022, and she has also served on the NASA Cosmic Origins Program Analysis Group (COPAG) Executive Committee since 2023 and on the NASA Extragalactic Database (NED) User’s Committee since 2018.

Job Title

Assistant Astronomer


Space Telescope Science Institute