October 1, 2020 outreach

Shifu Zhu, a graduate student in the Department of Astronomy & Astrophysics, had his research discoveries on radio-loud quasars featured in a 2020 October press release by the Chandra X-ray Center.

Specifically, Shifu analyzed X-ray, optical, and radio data for a large sample of 729 radio-loud quasars, with powerful radio-emitting jets, to determine the nature of their nuclear X-ray emission. His data indicated, surprisingly, that most of their X-ray emission generally does not originate from the jets themselves, but rather comes from a coronal structure lying above the accretion disk. These results challenge 35 years of thinking about the basic nature of this X-ray emission, and they provide insights into the accretion and ejection physics of these systems.

Monica Rincon Ramirez

The IGC wordmark was created by Monica Rincon Ramirez while she was a graduate student at the Institute. Monica enjoys drawing new connections between fundamental theory and observations. Her graduate work included general relativity, loop quantum gravity, and quantum fields in cosmological backgrounds; her thesis focused on effective quantum corrections to gravitational phenomena from spinfoams and applications to cosmology. She received her PhD in 2024.

The wordmark symbolizes the scope of research at the IGC. The base represents quantum gravity, evoking the quantum geometrical picture from spinfoams and loop quantum gravity — approaches studied at the Center for Fundamental Theory. The middle shows galaxies embedded in a smooth surface characteristic of spacetime in general relativity and the larger physical scales studied at the Center for Theoretical and Observational Cosmology. The top curves to an extreme representing a supermassive black hole accompanied by an energetic jet, with a binary black hole pair nearby — the high-energy phenomena studied at the Center for Multimessenger Astrophysics.