The stunning images produced by the James Webb Space Telescope and recent supercomputer-enabled black hole imaging efforts have brought the early days of the universe quite literally into sharp focus. Researchers from the University of Texas at Austin are hard at work elucidating the mysteries of the early formations of celestial bodies – powered, of course, by supercomputing.
The question at hand: what role did early black holes play in the origins of the first stars in the universe? Two competing ideas were in play – the first, that black holes helped form those early stars by pulling celestial matter into star-birthing halos; the second, that black holes were a hindrance, heating up surrounding gas that needed to be cooler for star formation.
To tackle this question, the UT Austin researchers received an allocation on the Stampede2 supercomputer at the Texas Advanced Computing Center (TACC) via the Extreme Science and Engineering Discovery Environment (XSEDE). Stampede2 is a Dell-built, Intel-built system that delivers 10.68 Linpack petaflops, placing it 47th on the most recent Top500 list.
On Stampede2, the researchers ran cosmological hydrodynamic simulations to represent the gravity, chemistry and heat dynamics of these early-universe scenarios. What they found was that the two competing effects largely counterbalanced one another, sometimes resulting in a small edge on either side of the equation.
“We found that these two effects – black hole heating and seeding – almost cancel each other out and the final impact is small for star formation,” explained Boyuan Liu, now a postdoctoral researcher at the University of Cambridge, in an interview with TACC’s Jorge Salazar.
“TACC and XSEDE resources have been absolutely vital for us to push the frontier of computation astrophysics,” said Volker Bromm, chair of the Department of Astronomy at UT Austin. “Everyone who is at UT Austin – faculty members, postdocs, students – benefits from the fact that we have such a premier supercomputing center. I’m extremely grateful.”
“If we look into one typical structure that can form the first stars, we need around one million elements to fully resolve this halo or structure,” Liu added. “This is why we need to use supercomputers at TACC.”
Somewhat outside of the scope of the first study, the researchers are now curious whether the first stars interacted with those early black holes and produced gravitational waves – or even supermassive black holes. Those questions will be addressed in subsequent studies.
To learn more about this research, read the reporting from TACC’s Jorge Salazar.