ZTF Faces

Yuhan Yao

PhD student at Caltech, USA

Where was your starting point and how did you discover astronomy?

Though I was born in Harbin, China — a city known for its frigid weather and annual ice and snow festival — my family relocated to Beijing when I was four years old. Growing up, I attended a small, full-boarding elementary school and developed a passion for science and music during my teenage years. Going to concerts and immersing myself in Cantonese movies and pop songs were some of my favorite pastimes. My interest in mathematics and physics was further cultivated during my time at Beijing Number 4 High School and later, during my undergraduate studies at Peking University (PKU).

During my sophomore year at PKU, I reached out to several professors in various physics subfields to explore research opportunities, finding that Professor Richard de Grijs was the best match for my interests. I appreciated his straightforward and pragmatic approach to science. As I delved deeper into my research, I became increasingly fascinated by astronomy and ultimately decided to pursue a PhD in astrophysics.

How did you discover ZTF?

With Richard's guidance, I secured a coveted international summer research position under the supervision of Professor Shri Kulkarni, and was fortunate enough to be a Caltech SURF student in 2017. Shri introduced me to the captivating realm of time domain astronomy and encouraged me to apply to Caltech’s PhD program. When I came to Caltech in 2018 as a graduate student, ZTF was about to be in full swing — it was such an exciting time to join this collaboration!

What are you playing with in the ZTF playground?

During the past five years, I have worked in three different subgroups (SNe, stellar, AGN/TDE) within the ZTF collaboration. My thesis work concerns finding tidal disruption events (TDEs) with ZTF, assessing population properties, and conducting detailed observing campaigns on individual objects to understand black hole accretion and jet physics. I explored, among other things, disk instability induced state transitions in accreting massive black holes, the emission mechanisms in TDE jets/outflows, as well as the demographics of optical TDEs.

Where do you want to steer your rocket in the future?

I will be starting soon as a Miller postdoctoral fellow at UC Berkeley, where I plan to continue using tidal disruption events and related transient phenomena to understand accretion/jet physics and black holes in various environments. I like astronomy as it allows me to be at the forefront of scientific discovery. In the long term, I hope to lead my own research group in observational high-energy astrophysics.

If you were not an astronomer, what would you be?

I will probably still choose a job that allows me to do research, such as an economist or a sociologist.

A book that shook your worldview?

Old Tales Retold by Lu Xun is one of the many books that have shaken my worldview. The book consists of eight Chinese fables that have been rewritten from a fresh perspective. Each story addresses themes that are still relevant today, such as social inequality and the struggles of the working class. The writing is powerful, with a deep sympathy for historical characters and a profound understanding of humanity.

If you’ve had a bad day at work, you will….

I will talk to a friend or have a glass of cocktail or watch Netflix.