Innovative model enables astronomers to explore explosive space events in new detail

Los Angeles CA (SPX) Oct 30, 2024 - Astrophysical events like the collapse of a massive star's iron core, known as a core-collapse supernova, the consumption of stellar remains by black holes, and runaway nuclear fusion on white dwarfs, lead to powerful explosions. While common, these explosions mostly occur in distant galaxies, and only recently have astronomers begun detecting them in significant numbers.

Eric Coughlin, assistant professor of physics at Syracuse University's College of Arts and Sciences, has introduced a rapid modeling approach to understand these cosmic explosions and the light they emit. His research, published in *The Astrophysical Journal Letters*, offers insights into tracking the evolution of such explosions.

"With this new understanding, we can model the emission from an explosion's interaction with its surroundings, allowing us to trace its evolution with time," said Coughlin.

Astronomers have long known that a star's collapse under gravity leads to an intense explosion as a neutron star forms at the center, creating a core-collapse supernova. Those visible in nearby galaxies can sometimes be observed with the naked eye, while modern telescopes now detect tens of supernovae each night. However, other types of explosions are more challenging to observe due to their rapid dimming or extreme distances.

"These explosions can release billions upon billions upon billions of atomic bombs' worth of energy each day," explained Coughlin, highlighting the significant energy generated by transient, high-energy cosmic events.

Core-collapse supernovae and other luminous events, known collectively as "transients," are central to astronomers' research. Coughlin's model aims to assist in understanding these phenomena.

A core-collapse supernova sends a shockwave through a star's outer layers, ejecting massive amounts of material into the surrounding gas. This ejecta radiates light due to its extreme heat and the radioactive decay of heavy elements. As it interacts with surrounding gas, the ejecta generates additional shockwaves, accelerating the gas and slowing the ejecta. The expanding shell of material creates visible light and radio emissions, signifying the presence of shock-heated gas. Coughlin's model provides a way to trace this shell's evolution and infer details about the explosion, including its energy.

Coughlin's model will be applied to data from the upcoming Legacy Survey of Space and Time (LSST) at the Vera C. Rubin Observatory, set to begin next year in Chile. The observatory's 10-year survey will yield an unprecedented volume of data for analyzing transient phenomena across billions of galaxies.

The Rubin Observatory features an advanced 8.4-meter telescope and the largest-ever 3.2-gigapixel camera designed for astronomy, capturing the entire Southern Hemisphere sky every three to four nights. This capability will enable it to detect distant or rapidly changing objects in ways previously impossible.

"We will be observing billions of galaxies over the next 10 years, and then correspondingly, millions of these transients that are caused by many different phenomena," Coughlin noted.

The Rubin Observatory's open-access data will exceed any previous datasets in both size and detail. Coughlin added, "As a theoretical astronomer, I try to piece together from these data a coherent picture of explosive phenomena out there. And I will try to understand the physics at play, to recreate these explosive events."

To capitalize on this vast dataset, cross-disciplinary collaboration is essential. Coughlin has received a Scialog fellowship from the Research Corporation for Science Advancement, aiming to develop LSST-based projects. In November, the first Scialog meeting will bring together 50 early-career scientists, including observational astronomers, cosmologists, astrophysicists, data scientists, and software engineers, to foster collaborative solutions for handling large data volumes.

"We're talking like petabytes (one million gigabytes) of data to deal with and to sift through," Coughlin emphasized. "We will bring together people of different disciplines thinking about solutions to problems that involve enormous volumes of data or new methods to use these data to figure out something new. The Rubin Observatory will help us gain insight into the deaths of massive stars as they are happening and producing enormous amounts of energy. We could ultimately learn what's powering some of these energetic events."

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