Research Interests

I am a postdoctoral fellow in the Physics and Astronomy departments at the University of California, Berkeley. I was previously a graduate student at the University of Washington, where my PhD advisor was Eric Agol. You can find a copy of my dissertation here.

My work focuses on the observational properties of gas falling into black holes accretion flows). A public lecture I gave recently on black holes is available online.

I have written a public computer code for calculating the strong bending of light near a spinning black hole (geokerr) as part of a larger code for simulating the appearance of black hole accretion flows. I have used this code to create realistic images of the massive black hole in the center of the Milky Way as it will look to us on Earth when viewed with the Event Horizon Telescope. I have also made predictions for future Event Horizon Telescope observations of both Sgr A* and M87, a much larger black hole known for its galaxy-scale jet.

My work was featured in a recent article about the Event Horizon Telescope, subsequently featured on several websites:

Space: Incredible Technology: How to See a Black Hole
Huffington Post UK: Black Hole Event Horizon Telescope Will Be 'Size Of The Earth'
Discovery: Event Horizon Telescope Will Snap a Black Hole

Berkeley sophomore Ayman Bin Kamruddin's work with me on modeling Event Horizon Telescope data was recently covered by several news outlets:

Space: What Will First Photos of Black Holes Look Like?
Yahoo!: What Will First Photos of Black Holes Look Like?
Discovery: Do Black Holes Really Look Like This?
Huffington Post: Black Hole May Look Crescent-Shaped In Photos To Be Taken By Event Horizon Telescope

The M87 work was also featured on a couple of websites:

New Scientist: Astrophile: A-list black hole gets a face
Astrobites: Shadow of a black hole

Our predictions for the size of M87 were also confirmed by recent observations.

I have also studied the observational properties of tilted black hole accretion disks, which are likely to be common for low-luminosity stellar mass and supermassive black holes. Finally, I have developed a simple description of quasar accretion disks motivated by optical/UV observations, and have shown that it can explain some of the interesting behavior we observe in small black holes in the Galaxy.

Student Collaborators

Current undergraduates: Angelo Ricarte (UC Berkeley, moving to Yale)
Previous undergraduates: Ayman Bin Kamruddin (UC Berkeley)
Previous graduate students: Samia Drappeau (University of Amsterdam)

I am happy to talk with interested students at any time.

Academic Genealogy

Chris Fragile put together a nice slide showing my academic genealogy.

Jason Dexter


Jason Dexter (jdexter at
Department of Astronomy
University of California at Berkeley
Berkeley, CA 94720-3411