Project:	Precision Image Reconstruction for Radio Interferometers
Disciplines:	Astrophysics, Statistics
Mentor:	Gregg Hallinan, Professor of Astronomy, (PMA), gh@astro.caltech.edu
AO Contact:	Ruby Byrne, rbyrne@caltech.edu
Background:	In radio astronomy, interferometric imaging algorithms allow for high fidelity reconstruction of the sky at long wavelengths using data from large radio arrays. Current algorithms use a model of the instrument response in the form of a per-antenna beam, but error in that model can introduce error in the reconstructed image. Emerging radio astronomy applications require more precise image reconstruction. Among these applications are 21 cm cosmology, where radio telescopes measure enormous volumes of the universe using the 21 cm emission line from neutral hydrogen. While there is substantial investment in the field improving beam modeling and measurement, there is no formal mathematical formalism for creating images with quantified uncertainty in the beam model. Such a formalism could improve image fidelity and allow for robust error propagation in radio interferometric imaging.
Description:	The student will develop a mathematical formalism for image reconstruction with quantified uncertainties in the instrument response. They will work with maximum likelihood estimates, Bayesian statistics, and perturbation theory to describe the beam model. The student will have the opportunity to apply their formalism to data from the OVRO-LWA telescope to demonstrate improved imaging performance. The SURF project will be hosted in person at Caltech.
References:	Tegmark, M. 1997, The Astrophysical Journal, 480, L87 Bhatnagar, S., Cornwell, T. J., Golap, K., & Uson, J. M. 2008, Astronomy and Astrophysics, 487, 419 Morales, M. F., & Matejek, M. 2009, Monthly Notices of the Royal Astronomical Society, 400, 1814
Student Requirements:	The student should have familiarity with maximum likelihood estimation, Bayesian statistics, and perturbation theory. Experience with coding in Python is preferred but not required.
Programs:	This AO can be done under the following programs:   Program    Available To        SURF    Caltech students only  Click on a program name for program info and application requirements.