Knowledge Bank

The fields of astronomy and astrophysics routinely experience a cycle of planning the next generation of instruments, designing and building the instruments, before they finally go online and become available for science. However, unlike past cycles, the fields are currently poised for an unprecedented amount of data collection with the coming generation of instruments in the next decade, data on the scale of petabytes and greater. Such a high volume of data requires more intensive preparation, including creating automated pipelines to allow for easier examination of the data and understanding what types of surveys will bear the most fruit. This project aims to provide an initial forecast for the ability of large scale voids to distinguish between models of modified gravity as well as introduce a new method of bright source removal from data collected in the radio wavelength regime.The current leading cosmological model, known as Lambda Cold Dark Matter, successfully predicts many current observations, but slight inconsistencies have caused some to propose alternative theories that remove the need for dark energy. One such class of theories involves the modification of gravity to account for the observed apparent acceleration of the universe. In particular, we choose to examine a specific type of modification, known as f(R) gravity. In low density regions, this modification results in gravity being stronger than normal General Relativity would predict. Because of this, low density regions in the universe, known as voids, would appear to be viable areas to test for the validity of this modified gravity model. We plan to use simulations modeling planned survey volumes roughly two orders of magnitude greater than current observations provide using realistic survey conditions to examine the effect of f(R) modified gravity on void properties, including void abundances, radial density profiles, radial velocity profiles, and void ellipticities. The other branch of the project will focus on the processing of radio interferometric observations of neutral 21cm emission from the epoch of reionization, an era of the universe’s history that holds much interest but relatively little progress has been made due to difficulties in observations. A common problem encountered is the presence of bright foreground objects that obscure nearby objects on the plane of the sky. For high resolution observations, current methods of data processing identify bright sources, convert the data to a low-resolution mesh due to computational constraints, fit the source with an ellipse, and subtract it out. We suggest that a more careful method is available through locally refining the bright spots using the high resolution data, avoiding the computational limitations, fitting the shape of the source, subtracting it, then de-refining the local patch to the original mesh. This will be particularly important for current instruments such as the Murchison Widefield Array and future instruments such as the Hydrogen Epoch of Reionization Array and the Square Kilometer Array.