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 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 (beyond wCDM) models with galaxy clustering and weak lensing data gathered during DES’ first three years. We’re focused on several parameterizations of physics beyond the cosmological standard model, including time-dependent dark energy, sterile neutrinos, modified gravity, non-zero curvature, and 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 protecting against experimenter bias. (See e.g. this APA blog post for a discussion on blinding as ableist language.) In this framework, data are manipulated in some way to conceal an analysis’ true results until all decisions about how to conduct that analysis 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 developed and tested a new, simple, and effective disguising (blinding) method for the combined analysis of multiple cosmological observables which works by transforming the summary statistics that are inputs for parameter estimation (e.g. two-point correlation 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 structure growth. The idea of the grow-geometry split analysis is to separately constrain the LCDM parameters using probes of expansion and structure growth, and then to use the comparison of those constraints as a consistency test of LCDM. I performed a growth geometry split analysis of combined DES Year 1 data, published 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 CMB have been found to be in remarkable agreement with the predictions of LCDM. However, there are a handful of features on very large angular scales which are statistically unlikely in LCDM, which have been the subject of much study. 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 - The integrated Sachs-Wolfe (ISW) effect is a result of the fact that the energy of cosmic microwave background (CMB) photons gets modulated when pass through gravitational potential wells associated with large scale structure (LSS) on their way from the surface of last scattering to us. This energy modulation contributes to CMB temperature anisotropies at large angles. One can use theoretical cross correlations and maps of LSS tracers to try to reconstruct a map of the ISW signal. In two papers (here and here), I explored how different survey properties and systematics affecting the input galaxy maps impacted the accuracy of this kind of ISW signal reconstruction.

  • 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.