Awards Database

Scialog: Collaborative Teams - 2017

Dimitrios  Giannios

Dimitrios Giannios

Physics, Purdue University

David  Kaplan

David Kaplan

Physics, University of Wisconsin, Milwaukee

Identifying the origin of the Extreme Scattering Events

The space between stars isn’t entirely empty. There are clouds of ionized gas, known as plasma, among the dust and other bits of matter comprising what astronomers call the Interstellar Medium. These clouds give rise to a puzzling phenomenon in observations of distant, bright, radio sources because of plasma lensing. That’s the process by which dense clouds of ionized gas bend and distort electromagnetic waves, especially radio signals, making the long journey across deep space.

Radio astronomers first noticed what they termed Extreme Scattering Events (ESEs), where radio sources bafflingly varied dramatically in brightness signals on time scales of days, but eventually they came to attribute the changing signals to intervening clouds of plasma (ionized gas), with varying densities, in our galaxy. (When gas is heated by stars or even cosmic rays, it can knock electrons out of atoms in the cloud, creating charged particles called ions.)

The origin and the geometry of the ionized gas responsible for ESEs remain a puzzle. Yet, the mere detection of ESEs demonstrate that the Interstellar Medium holds many surprises. More useable statistics and real-time detections are required for the systematic study of the phenomenon.

Recently two astrophysicists Dimitrios Giannios, Purdue University, and David Kaplan, University of Wisconsin, Milwaukee, formed a team and won a competition to receive funding to develop real-time analysis tools for extracting ESEs from the hundreds of thousands of radio signals assembled by advanced telescopes. They will use this new data along with computer models to more reliably determine the properties of ESEs.

“This will allow us to resolve the mystery of the origin of ESEs with far-reaching implications for the study of the Interstellar Medium,” the researchers predict.

Giannios and Kaplan formed their collaboration at an RCSA-sponsored conference, Scialog: Time Domain Astrophysics, held late last year in Tucson, Arizona. There, 50 leading young astronomers and astrophysicists, joined by 10 distinguished senior scientists, engaged in intensive discussions designed to produce creative ideas for innovative research. (Scialog is a combination of “science” and “dialog.”)

“Scialog aims to encourage collaborations among theorists, experimentalists and computational scientists,” said RCSA Program Director Richard Wiener. “We want to catalyze the development of a community in which theory and observation work together to achieve understanding of fundamental phenomena.”

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