TimeTubes: Design of a visualization tool for time-dependent, multivariate blazar datasets

Blazars are active galactic nuclei whose relativistic jets ejected from the central black hole are pointing toward the Earth. Astronomers have attempted to classify blazars, but analyzing the time-dependent multivariate datasets with conventional visualization methods, such as scatter plot matrices, is difficult. This paper presents TimeTubes, a new visualization scheme that allows astronomers to analyze dynamic changes in and feature causality among the multiple time-varying variables. We target six representative time-varying variables from the originals, including two polarization-related parameters and their corresponding errors, intensity, and color. The four polarization parameters with a common time stamp are transformed to an ellipse, and a series of such ellipses are aligned in parallel along the time line to form a volumetric tube in 3D space. The resulting tube is then colorized by the observed intensities and colors of the blazar. We designed a designated interface with nine functions to control the view of the tube interactively. The usability of TimeTubes is discussed with feedback from astronomers.