Yihao Zhao sits in a desk in her office. She has three monitors open, showing code and images from the simulations she creates. She smiles at the camera.

Ph.D. Student Wins NASA FINESST Grant

Yihao Zhou studies origins of the universe’s most powerful black holes.

By Kirsten Heuring Email Kirsten Heuring

Heidi Opdyke

Carnegie Mellon University’s Yihao Zhou wants to develop a better picture of how massive black holes affect the universe. With the help of a NASA FINESST grant, she is creating groundbreaking simulations that trace the evolution of massive black holes from the earliest galaxies to the most energetic events in the universe.

Zhou, a fourth-year Ph.D student in Carnegie Mellon University's Department of Physics and member of the McWilliams Center for Cosmology, is addressing one of the toughest questions in astrophysics: How do the universe’s most extreme objects — supermassive black holes —form, grow and collide?

“Black holes play a very important role in the universe evolving, but we don’t know much about them,” Zhou said. She focuses on the enormous black holes found at the center of most galaxies. “We’re creating special models to improve descriptions of black hole dynamics.”

The goal is to discover new ways to find black holes. Zhou’s adviser, Physics Professor and Head of the McWilliams Center Tiziana Di Matteo, said black holes produce the strongest gravitational waves in the universe.

Scientists are building a new generation of space-based detectors — like LISA — for these gravitational waves but they need to know how many of these events to expect. That’s where Zhou and ASTRID come in.

ASTRID is a complex simulation that starts from 15 million years after the Big Bang and follows the formation of galaxies and their black holes. Built by a team led by Di Matteo, the simulation was developed over the past five years. It is improving astrophysicists’ predictions for how black holes and galaxies co-evolved in the universe.

“ASTRID can resolve scales close to the edge of black holes to the largest structures in the universe,” Di Matteo said. “By combining our new simulation results, multi-wavelength observations, and gravitational waves, we’re moving far beyond simply detecting black holes. We’re beginning to understand how they formed in the early universe, how they evolved alongside their galaxies and how they influence the surrounding cosmic environment.”

As one of the team members, Zhou helped code a computational tool used in the program, MAGICS, which allows her to zoom in on black hole mergers in high resolution. From there, she can map black holes over billions of years and on vast scales, giving her and other researchers insights on how black holes form, grow and collide.

Her work could offer insights to other researchers so they can have a better idea where to search for black holes both now and in the future. Her findings will help direct telescopes like the James Webb Space Telescope and the Nancy Grace Roman Space Telescope and observatories like International Pulsar Timing Array so they can find black holes and other gravitational wave events.

“We have the largest black hole population in our simulation compared to other simulations,” Zhou said. “We’re able to use these simulations to cover a huge volume of space to estimate how many merging events happen. After the huge simulation, we can search for individual merging points from this population, and we can do smaller high-resolution simulations.”

The project started using the resources of the Pittsburgh Supercomputing Center (PSC) and transferred to the Texas Advanced Computing Center (TACC) as the simulation grew larger and more detailed.

“The work we do with TACC, it would take 10,000 years for a standard laptop to finish,” Zhou said.

For her efforts, Zhou earned a Future Investigators in NASA Earth and Space Science and Technology (FINESST) grant awarded in 2025. Through the FINESST grant, NASA’s Science Mission Directorate will support her work for the next three years. This specialized grant is awarded to graduate students studying astrophysics, earth science, heliophysics, planetary science or biological and physical sciences. Zhou said she looks forward to further developing and analyzing the simulation.

“I feel very happy that what I’m doing is being encouraged and being recognized by NASA,” Zhou said. “I’m glad they think this is an interesting topic to explore.

Zhou said that she hopes that her work with ASTRID will be able to help future researchers learn more about the universe and discover more about black hole mergers.

“Multi-messenger astrophysics is about to change our view of the cosmos, and Yihao’s work is vital to piecing together our cosmic history,” Di Matteo said. “It’s a guide for the next decade of discovery in gravitational waves and black hole astrophysics.”