STEM Profile: Hannah Fritze, Astrophysics graduate student | University of Utah

We Rep STEM aims to promote the work of inspiring people in the STEM community. Today, we’re featuring Hannah Fritze, an astrophysics graduate student at the University of Utah.

Read on to learn more about Hannah and what her work entails, in her own words.

My name is Hannah Fritze. I am a first-year graduate student at the University of Utah Department of Physics and Astronomy, and I previously worked as a student intern at the Lawrence Livermore National Laboratory, in the Physical Sciences/HED Division. 

My research in astronomy focuses on using X-ray data taken by the Chandra X-ray Observatory to try and identify Intermediate Mass Black Hole candidates in nearby ultraluminous X-ray binaries.

The goal of my project is to try to find black holes that span the gap between stellar mass and supermassive to help understand the evolutionary process of black holes.

Hannah standing with a poster outlining her research. Taken the 233rd meeting of the American Astronomical Society .

Five quick facts about black holes

 1. Stellar mass black holes are formed when massive stars reach the end of their lifetimes. They run out of elements to fuse in their cores, and without the outward pressure from fusion pushing back against gravity, they collapse, forming what is known as a singularity. This singularity is a black hole. 

2. Black holes are called “black” because they don’t emit light. Their gravitational pull is so strong that light can’t escape. As a result, we can’t directly observe a black hole, we look at what’s happening around it instead. The way that things around a black hole behave can tell us about its mass, such as the stars that orbit around supermassive black holes like the one at the center of the Milky Way.

 3. We understand fairly well how stellar mass black holes form, but supermassive black holes are a mystery. They are so large that if you put a black hole at the very beginning of the universe, and let it grow as fast as it could for the 14 billion years that the universe has existed, it still won’t be as large as the supermassive black holes we see today. I try to find black holes that are between stellar mass and supermassive. The hope is that if we can find black holes that are more medium-sized, they could give us clues about how the more massive black holes came to be! 

4. Some black holes that are stellar mass or slightly higher exist very close to another star. The two orbit around each other in what is known as a binary. As they do, material from the star can fall onto the black hole, making a disk of material that falls into the center. This disk, and the material that falls into the black hole emits high-energy light that we see as X-rays. By looking for sources that are very bright in the X-ray portion of the light spectrum, we can search for black holes that would otherwise be hidden from view. 

5. For a long time, the X-ray sources in the universe were hidden from us. Earth’s atmosphere blocks X-ray light, and so to detect these X-rays coming from black holes (and other things in the universe), X-ray telescopes have to get up above the atmosphere, in orbit around the Earth.

There are currently 8 X-ray telescopes in space, orbiting around our planet and taking observations!

 I can be found on twitter at @astrohannahf, and I’m always excited to talk to people about black holes, and astro in general! Come say hi!

If you’d like to have your work featured on We Rep STEM, get in touch! We can be reached via email at

Photos courtesy of Hannah Fritze.

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