Signal processing enables the first localization of gamma rays from supermassive black holes

摘要

The highest energy photons in the universe come from jets of relativistic plasma powered by supermassive black holes. Our ability to study these jets is severely limited by a poor angular resolution of gamma-ray telescopes. However, the deep gravitational potentials surrounding galaxies act as natural `gravitational' lenses. These gravitational lenses split background sources into multiple images, each with a gravitationally-induced time delay. Though gamma-ray telescopes cannot spatially resolve these multiple images, they can infer those time delays between them if the sources are intrinsically variable. These time delays depend on the position of the source relative to the lensing galaxy. A precise measurement of the time delay can be used to infer the exact location of the gamma ray sources, which is impossible otherwise. In order to obtain accurate and robust time delay measurements, I combine signal processing with Monte Carlo simulations. My approach improves angular resolution of modern instruments by six orders of magnitude (×106) and allows me to elucidate the spatial origin of gamma-ray radiation produced in extragalactic jets for the first time.