Syracuse Sun

Eric Coughlin, a professor of physics in the College of Arts and Sciences, has been awarded a grant from NASA for his project titled “Extragalactic Outbursts and Repeating Nuclear Flares From Tidal Disruption Events.” The three-year, $346,000 award will support his research on tidal disruption events (TDEs), which are among the cosmos' most extreme occurrences where a star is completely or partially destroyed by the gravitational field of a supermassive black hole (SMBH).

By examining the formation of accretion flares—the hot, bright shredded stellar material that falls into the black hole during a TDE—astrophysicists can gain insights about the evolution of SMBHs, including their mass and spin distributions. With advancements in technology like NASA’s NICER telescope, scientists have detected more TDEs than ever before. While these telescopes allow direct observations of TDEs, theoretical models are necessary to relate observations to the physical properties of both the disrupted star and the disrupting black hole.

With this grant, Coughlin aims to advance TDE theory and modeling to ensure they align with observations. He plans to numerically simulate TDEs of individual stars to generate a repository of accretion rates, which can then be compared to observations to infer black holes' physical properties.

Part of Coughlin's project will focus on understanding repeating partial TDEs. A partial TDE occurs when a star is stripped of some mass by an SMBH but is not completely destroyed. In repeating partial TDEs, the star orbits the black hole and is stripped of mass once per orbit.

Coughlin notes that this aspect shows promise for measuring quantities that normal tidal disruption events cannot. For instance, there is a period known as fallback time after a star is partially disrupted when no observable emission occurs before debris rains down onto the black hole. Repeating partial TDEs enable direct detection of fallback time through electromagnetic disturbances as the star orbits the SMBH.

“Our goal is to develop an enhanced understanding of variability in accretion rates onto black holes generated by tidal disruption events,” says Coughlin. “Our results will support NASA’s Physics of the Cosmos program: understanding matter behavior in extreme environments and Universe evolution.”

This is Coughlin's second current NASA grant; his other project uses data from Neil Gehrels Swift Observatory to probe properties of repeating partial TDEs. His research also receives funding from a $330,000 National Science Foundation grant for studying long-term evolution of tidal disruption events.