A list of my publications can be found on my Inspire page.

Current & recent projects

  • DES Year 3 extended cosmological models - The Dark Energy Survey (DES) is an ongoing project to map the distribution of matter in the Universe using measurements of galaxy shapes and positions over 1/8th of the sky, and to use that survey to place constraints on the properties of dark energy and other aspects of our cosmological model. With Agnes Ferte (JPL), I am coleading the DES analysis team focused on constraining extended models (beyond wCDM) with galaxy clustering and weak lensing data gathered during DES’ first three years of observations. We’re studying on several parameterizations of physics beyond the cosmological standard model including time-dependent dark energy, sterile neutrinos, modified gravity, non-zero curvature, and a non-parametric measurement of large scale structure growth.

  • Protecting multi-probe cosmology analyses from experimenter bias - As cosmological experiments grow increasingly precise, it is important to protect their results from a variety of systematic biases, including those that experimenters might unconsciously introduce. Blind analysis, which could alternatively be called disguised analysis, is a framework of experiment design aimed at preventing experimenter bias from influencing results. (Note: see e.g. this APA blog post for a discussion on blinding as ableist language.) In this framework, data are manipulated to conceal an analysis’ true results until all decisions about how to conduct it are finalized. Because working with the disguised data removes experimenters’ ability to know how the results compare to their expectations, their choices cannot be influenced by that comparison. I’ve implemented and tested a new, simple, and effective disguising (blinding) method for the combined analysis of multiple cosmological observables. It works by transforming the summary statistics that are inputs for parameter estimation (for DES, these are galaxy clustering and shear two-point angularcorrelation functions). This method, described in this paper, is being used in the the DES Year 3 combined galaxy clustering and weak lensing analysis, and could be potentially applicable to both future surveys and other types of data.

  • Growth-geometry split analysis of DES data - Many models of modified gravity can produce the same expansion history as LCDM, the standard cosmological model of a cosmological constant + cold dark matter + general relativity, but will differ in their predictions for the evolution of large scale structure growth. The idea of a grow-geometry split analysis is to separately constrain cosmological parameters using measurements of expansion and structure growth, and then to test the consistency of those constraints. I performed a growth geometry split analysis of DES Year 1 data, described in this paper. I’m also generally interested in using galaxy survey data to test for modified gravity via phenomenological parameterizations of deviations from general relativity.

  • CMB anomaly covariances - For the most part, data from the cosmic microwave background (CMB) have been found to be in remarkable agreement with the predictions of the standard cosmological model. However, there are a handful of features on very large angular scales which have been the subject of much study because they are statistically unlikely in LambdaCDM. This paper describes a project I did using simulated CMB skies to characterize the extent to which these various anomalies are independent.

  • ISW signal reconstruction - When CMB photons pass through large scale structure, their energy gets modulated by the time evolution of the associated gravitational potential fluctuations. This modulation, known as the integrated Sachs-Wolfe (ISW) effect, contributes to CMB temperature anisotropies at large angular scales. Because galaxies trace the same overdensities that source the ISW effect, we can construct an estimator of the ISW signal based on galaxy survey maps of cosmological structures. In two papers (here and here), I explored how different survey properties and systematics affecting the input galaxy maps impact the accuracy of this estimator.

  • Astrophysical black holes and modified gravity - For a master’s project, I did an exploratory study of how the infall of objects into black holes would be affected by a class of extensions to general relativity in which a new gravitational field interacts with matter in the black hole’s accretion disk. The project is described in this paper.

Other activities

Though I can’t really claim it as a project, I was lucky enough to be on observing shift during the tail end of the DES follow-up observations of the binary neutron star collision detected by LIGO in August 2017. Data I took played a small role in these three papers.