Space & Cosmos

Innovative model offers new way for astronomers to analyze powerful cosmic explosions

The explosion of a massive star leads to the ejection of its outer shell, and this “ejecta” expands outward over time and interacts with the star’s surrounding medium upon its death. This interaction creates two shock waves and a contact discontinuity (collectively known as a “shell”) that dissipates kinetic energy in exchange for producing more light. Eric Coughlin’s new model tracks the time-dependent evolution of this shell and, when used in parallel with observations of these high-energy events, allows us to understand the physics that drive celestial explosions. Credit: Eric Coughlin/Syracuse University

Astrophysical explosions can be caused by the collapse of the iron core of a massive star (known as a nuclear collapse supernova), or the consumption of spaghettiized star debris by a massive black hole (as a tidal disruption phenomenon), to name a few. known). ), and runaway nuclear fusion on the surface of a white dwarf (known as a Type 1A supernova). Although such explosions occur frequently, most occur in distant galaxies, and only recently have astronomers been able to peer far enough into space to detect them in significant numbers. , and more explosions are on the way.

Eric Coughlin, an assistant professor of physics in Syracuse University’s College of Arts and Sciences, has developed a new method to quickly model the origin of these explosions and the light we ultimately see. His research is published in The Astrophysical Journal Letters.

“This new understanding allows us to model emissions from explosion interactions with the surrounding environment and track their evolution over time,” Coughlin said.

For many years, astronomers have known when massive stars die by their own gravitational collapse. This is because a neutron star forms at its center, and its collapse causes an explosion that reverses the implosion and causes an extremely powerful and bright explosion, now known as a nuclear collapse supernova. Supernovae that occur within our galaxy (or in other or very nearby galaxies) can be seen with the naked eye, but today many supernovae can be detected by modern telescopes at a rate of several dozen per night. It has been.

However, other types of explosions are not as easy to identify because they are too far away or too dark. For example, a rapidly fading electromagnetic explosion is easy to miss if you don’t look in the right place in the sky at the right time. Nevertheless, they can release an amount of energy comparable to a standard supernova explosion.

“These explosions can release the energy equivalent of billions and billions of atomic bombs every day,” Coughlin said. “Such temporary high-energy events occur all the time in the universe.”

Astronomers seek discoveries about nuclear collapse supernovae and other rapidly evolving luminescent phenomena in the universe, collectively known as “transients.” Coughlin’s new model helps in this exploration.

A nuclear collapse supernova occurs when a newly formed neutron star “bounces back”, reversing the star’s implosion and causing a shock wave in the star’s outermost layers. Huge amounts of supernova debris, or ejecta, are blown into the gas surrounding the dying star.

The ejecta is initially very hot and emits enormous amounts of light, and the radioactive decay of heavy atomic elements also contributes to the radiation. The interaction between the ejecta and the surrounding gas supplements this ejection, as two additional shock waves are generated that accelerate the surrounding gas and decelerate the outwardly moving ejecta. It can also dominate.

This “shell” of shocked material expands outward over time, producing not only visible light but also radio emissions indicating the presence of gas heated by the shock. Coughlin’s model provides a new methodology for tracking the evolution of shells produced through this interaction, which can be used in conjunction with radio data to infer properties such as the energy of the explosion.

Coughlin plans to apply his model to data from the Legacy Space-Time Survey (LSST), which will be conducted by the Vera C. Rubin Observatory in the Chilean Andes Mountains, scheduled to open next year. Rubin Observatory conducts 10 years of sky research that provides vast amounts of astronomical data for astronomers to analyze, leading to new discoveries about the time-dependent universe.

Rubin Observatory features a world-class 8.4-meter telescope connected to a 3.2 gigapixel camera, the largest digital camera ever built for astronomy.

The telescope images the entire visible sky of the Southern Hemisphere every three to four nights, allowing it to detect more distant or fainter objects that temporarily change in brightness or direction.

“We will observe billions of galaxies over the next decade, and correspondingly millions of transients caused by a variety of phenomena,” Coughlin said.

The Rubin Observatory’s open-access dataset will be larger and more detailed than any previously provided.

“As a theoretical astronomer, I’m trying to piece together a coherent picture of the world’s explosive phenomena from these data,” Coughlin said. “And I’m going to try to understand the physics of what’s actually happening in order to recreate these explosive events.”

However, interdisciplinary research is needed to facilitate early discoveries.

Coughlin was awarded the “Scialog” Fellowship. The first Scialog session was held in Tucson, Arizona in November and was a connection between 50 young scientists, including observational astronomers, cosmologists, theoretical physicists and astrophysicists, computational modelers, data scientists, and software engineers. Build.

Scialog participants plan to leverage datasets of unprecedented size by fostering collaborative projects.

“We think we have petabytes (million gigabytes) of data to work with and sift through,” Coughlin said. “We bring together people from different disciplines who think about solutions to problems involving huge amounts of data and new ways to use this data to figure out something new. , which helps us understand the death of massive stars as they really are.” There is a huge amount of energy being generated and produced, so what is ultimately driving some of these energetic events? You will be able to know. ”

Further information: Eric R. Coughlin, From Coasting to Energy-conserving: New Self-similar Solutions to the Interaction Phase of Strong Explosions, The Astrophysical Journal Letters (2024). DOI: 10.3847/2041-8213/ad87cc

Provided by Syracuse University

Citation: Revolutionary model offers new way for astronomers to analyze powerful cosmic explosions (October 29, 2024) https://phys.org/news/2024-10-astronomers-powerful- Retrieved October 29, 2024 from space-explosions.html

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