Christian Ott

Computational and Theoretical Relativistic Astrophysics

I have just joined the Caltech Astronomy and Astrophysics faculty and am looking forward to the great opportunity of working with current and future Caltech grad students. I completed my Ph.D. research at the Albert Einstein Institute (a Max Planck Institute in Potsdam, Germany) in 2007 and worked as a postdoc for two years at the University of Arizona and for one year as a Sherman Fairchild Fellow in TAPIR before becoming assistant professor.

I am building up a research group for computational relativistic astrophysics within the dynamic TAPIR (Theoretical AstroPhysics Including Relativity) group on the third floor of Cahill. In the evenings and on weekends, I enjoy running in my neighborhood and hiking the San Gabriel mountains to compensate for all the time I spend in front of my desk and computer. I also like reading, listening to (preferably live) independent/singer-songwriter-style music, watching independent films, and trying out new places for dinner from the huge selection of restaurants the LA area has to offer.

Scientifically, I am currently most interested in very energetic astrophysical phenomena – basically, things that blow up. These include dying massive stars that explode in core-collapse supernovae and/or gamma-ray bursts, binary systems of compact stars (neutron stars/black holes) that merge and make a gamma-ray burst, accreting white dwarfs and merging white-dwarf binaries that explode in a supernova, accreting neutron stars that burn accreted material and make x-ray bursts, and soft-gamma-ray repeaters – neutron stars, that experience re-arrangement of their ultra-strong magnetic fields, leading to repeated outbursts of soft gamma rays.

We are trying to understand the physics and dynamics of the 'engines' of such energetic and explosive events. This is a challenging, but exciting task – these problems are so complicated and involve physics from so many different areas (e.g., general relativity, magneto-hydrodynamics, nuclear and particle physics, transport theory) that they must be modeled on supercomputers. These models can then guide our theoretical understanding and, perhaps more importantly, give us predictions that can be tested by observation. We run our simulations on some of the world's finest and fastest supercomputers on the TeraGrid, at National Labs, and we have our own small supercomputer system here at Caltech's Center for Advanced Computing Research.

Observing phenomena that occur in strongly curved spacetime and at ultra-high matter density is notoriously difficult. In most cases, these regions are hidden by intervening matter from direct view in the electromagnetic spectrum. Neutrinos and gravitational waves (to be detected by LIGO) can travel practically unscathed to observers on Earth. They are the only messengers that can provide direct “live” information on what happens at the heart of supernovae and gamma-ray bursts and other such systems. But this comes at a price: neither neutrinos nor gravitational waves can be used to create an image of their source. Rather, observational data must be compared with model predictions in order to understand the source physics and dynamics. One of our main tasks is to produce such detailed estimates which we furnish to neutrino and gravitational-wave observers. We work closely with neutrino physicists at Caltech and elsewhere, and have very close ties to the LIGO laboratory at Caltech. Of course, we also interact with Caltech's observational astronomy groups.

There are many unsolved problems in relativistic astrophysics and all involve a broad range of physics and complicated multi-dimensional dynamics of matter, radiation, gravity, and magnetic fields. There is a virtually countless number of exciting research projects! So, if you are interested in the stuff we do or just want to learn more about our work, please just drop by my office whenever you like.

[Image credits: Bill Youngblood; A. Burrows et al. (Princeton U.) & C. D. Ott; C. D. Ott & R. Kaehler (ZIB/Stanford)]