University of Waterloo
200 University Avenue West
Waterloo, Ontario, Canada N2L 3G1
Phone: (519) 888-4567 ext 32215
Fax: (519) 746-8115
Arka Banerjee is a Schramm fellow in Theoretical Astrophysics at Fermilab. Previously, he got his Phd from the University of Illinois, Urbana-Champaign, and then was a KIPAC postdoctoral fellow at Stanford University. His research focuses on cosmological structure formation, and its connection to fundamental physics.
Talk Title and Abstract:
Nearest neighbor distributions: New statistical measures for cosmological clustering
As we push to understand cosmological structure formation on small, non-linear scales, and constrain various cosmological parameters using the clustering information on these scales, it is crucial to understand which statistical measures of clustering can be used to extract the most of the available information.
The two-point correlation function is the most widely used statistical tool to summarize clustering in the data for cosmological analyses. While it is a complete statistical description for a Gaussian random field, the 2PCF does not capture all the information for nonlinear fields.
In this talk, I will introduce a new set of summary statistics for cosmological clustering: the k-Nearest Neighbor Cumulative Distribution Functions (kNN-CDF). I will discuss how to compute these efficiently on discrete datasets, like halo and galaxy catalogs, and how these measurements are sensitive to integrals of all N-point functions in the data. I will demonstrate various applications of these statistics, including the extent to which they are more sensitive to the underlying cosmological parameters, and can produce significantly stronger parameter constraints from the same input data. I will then discuss how nearest neighbor measurements can be applied to joint distributions and cross-correlations of two datasets, and demonstrate that here too, have greater statistical power than the traditional two-point cross-correlations. Finally, I will talk about ongoing work on modeling these kNN-CDFs for arbitrary halo or galaxy samples as a function of the underlying cosmological parameters.
The University of Waterloo acknowledges that much of our work takes place on the traditional territory of the Neutral, Anishinaabeg and Haudenosaunee peoples. Our main campus is situated on the Haldimand Tract, the land granted to the Six Nations that includes six miles on each side of the Grand River. Our active work toward reconciliation takes place across our campuses through research, learning, teaching, and community building, and is centralized within our Indigenous Initiatives Office.