I am a computational/theoretical astrophysicist in TAPIR, which is part of the
Walter Burke Institute for
Theoretical Physics at Caltech, working at the interface of
numerical relativity, nuclear/neutrino astrophysics, and
gravitational-wave physics. My current primary research interest is to
find ways to blow up massive stars, that is, make core-collapse
supernovae and gamma-ray bursts and their compact remnants, black
holes and neutron stars. This work is carried out as part of
the Simulating eXtreme Spacetimes
(SXS) collaboration and we also work closely with
the Einstein Toolkit team.
Another line of my research is concerned with the observation and interpretation of gravitational waves using the LIGO interferometers and I am a member of the LIGO Scientific Collaboration.
I am presently leading an
Trainees/Mentees that won National fellowships:
Evan O'Connor (Hubble 2014, PhD 2012), Christine Corbett Moran (NSF 2015), Philipp Mösta (Einstein 2015), Christian Reisswig (Einstein 2012), Luke Roberts (Einstein 2013).
Some background on me:
I received my PhD in 2007 at the Max Planck Institute for Gravitational Physics under Bernard Schutz's and Ed Seidel's supervision and then was a Joint Institute for Nuclear Astrophysics postdoctoral fellow with Adam Burrows at The University of Arizona before joining Caltech. More details can be found in my CV.
Follow me on Twitter: Follow @hypercott
Read my blog: Blowing Up Stars
Members of the computational relativistic astrophysics / numerical relativity group at TAPIR:
|Undergrads||Hannah Klion, Lauren Gilbert, Karthik Siva|
|Grad students:||Kevin Barkett (advisor: Mark Scheel), Jonathan Blackman (advisor: Mark Scheel), Hannalore Gerling-Dunsmore, Matt Giesler, Sarah Gossan (also LIGO lab, advisor: Alan Weinstein), Jonas Lippuner, Maria Okounkova, Mathieu Renzo (exchange grad from Pisa), Sherwood Richers (DOE CSGF).|
|Postdocs||Sebastiano Bernuzzi (Senior Postdoc), Drew Clausen (DuBridge Prize Fellow), Sean Couch (Senior Postdoc), Jim Fuller (DuBridge Prize Fellow), Daniel Hemberger, Christine Corbett Moran, Philipp Mösta, Viktoriya Morozova, David Radice (Sherman Fairchild Prize Fellow), Christian Reisswig (Einstein Fellow), Luke Roberts (Einstein Fellow), Patricia Schmidt, André da Silva Schneider|
|Senior Researchers||Research Professor Mark Scheel|
|Visitors||Bill Engels, Jocelyn Read, Geoffrey Lovelace, Uli Sperhake, and Steve Drasco.|
|Admins:||JoAnn Boyd, Nannette Pettis (grant manager)|
|Senior Thesis:||If you are a Caltech undergrad and interested in doing a senior thesis in Ay or Ph, please come see me! I am happy to advise senior thesis work and have a number of interesting projects available.|
|Prospective Summer Undergrads:||We work with the LIGO REU program. Please see the projects and application procedures listed there. Caltech undergrads should contact me directly about SURF possibilities.|
|Prospective Grad Students:||
If you are interested in our research and would like to join us, please apply to the Caltech
Astrophysics and/or the Caltech Physics graduate programs. Please do not
send me your application materials -- these should go to the graduate
program. The admission decision will be made by the graduate admission
2013/14 Spring term: Ay102 - Interstellar Medium.
2013/14 Winter term: Ay190 - Computational Astrophysics.
2013/14 Fall term: Ay121 - Radiative Processes (with Gregg Hallinan)
2012/13 Fall term. Ay121 - Radiative Processes (with Gregg Hallinan).
2012 Spring term. Ay125 -- High-Energy Astrophysics (with Alan Weinstein).
2010/2011 Winter term. Ay190 -- Computational Astrophysics
2011/2012 Fall term. FS 001 -- Freshman Seminar on Cosmic Explosions and Their Multi-Messenger Signals
2009/2010 Winter term: Ay 215 -- Seminar in Theoretical
Astrophysics: Interacting Binaries.
Snapshot from a 3D GR black hole formation simulation (Ott et al. 2011, PRL)
Congrats to Hannah! Hannah is a senior in the physics program at Caltech and has been working with us since her Freshman year. Her research is on rotating core collapse and gravitational wave emission from its postbounce ring-down phase. Hannah will take her CSGF to one of the schools she is currently considering for graduate school and we hope to continue to collaborate with her in the future!
|I had the pleasure of joining the Astronomy & Space Exploration Society for their 12th Annual Symposium at the University of Toronto on January 23, 2015. ASX is an undergraduate-run organization that organizes regular seminars on topics related to astronomy and space and they put together their yearly symposium that is always under a special theme. This year's symposium had the theme "Stellar Graveyard" -- of course that's a topic I have something to say about. I gave a lecture on The Theory of Stellar Death and Explosion. The symposium was a lot of fun! A broad and diverse audience of about 450 people attended and most stayed until the end of my talk (at 10:15 pm!).|
What drives hypernovae, extreme supernova explosions that have many times the explosion energy of a garden-variety supernova from a massive star?
Detailed simulations show that the standard mechanism for core-collapse supernovae -- the neutrino mechanism -- seems to lack the efficiency to drive such powerful explosions.
A possibly more powerful alternative could be the magnetorotational mechanism. In this scenario, rapid rotation (a proto-neutron star with a millisecond spin period) in combination with a very strong toroidal magnetic field (1015-1016 G) are expected to push out energetic bipolar outflows along the axis of rotation.
Our team has just completed the first set of full 3D, dynamical-spacetime GR-magnetohydrodynamic simulations of magnetorotational core-collapse supernovae. This work was led by postdoc Philipp Mösta and grad student Sherwood Richers (DOE Computational Science Graduate Fellow) made important contributions.
In collaboration with other team members, Philipp and Sherwood showed that the configuration that leads to strong jets in axisymmetry is unstable in 3D to an MHD kink instability, leading to a spiral deformation of the outflow. The volume rendering the left shows the entropy distribution at some 160 milliseconds after core bounce. Red indicates high entropy (about >10 kB/baryon), blue low entropy (a few kB/baryon). The vertical axis is the vertical and the scale is 1600 km. Instead of a clean jet, two huge lobes develop that move out secularly as the proto-neutron star pushes spiral streams of out hot, highly magnetized plasma into polar regions.
CGWAS 2013 is a summer school for senior undergraduates and graduate students interested in the astrophysics of gravitational wave sources, gravitational wave astronomy, and multi-messenger follow-up observations of gravitational wave detections in the Advanced LIGO/Virgo era.
CGWAS will take place July 22-26, 2013 on the Caltech campus. Attendance is free, but limited. Support for accomodation in Caltech campus housing is available. Apply at http://www.cgwas.org.
CGWAS is supported by my NSF CAREER award and is part of my CAREER education/outreach program.
We ran four full 3D full GR (time-evolving Einstein's field equations)
simulations of a 27-solar-mass progenitor star that was shown by Müller
et al. to be especially susceptible to the Standing Accretion
Shock Instability (SASI) in axisymmetry. |
Our goal was to see (1) if the SASI develops in a similar way even in 3D (where the dynamics is not forced to be symmetric about one of the axes) and (2) how the behavior of the SASI changes when the strength of neutrino heating is varied.
We found that the SASI, while present in 3D, never reaches the strength seen in the 2D simulations of Müller et al. In our simulations, neutrino-driven convection was seeded early on and grew to become the dominant instability. We also found that as the explosion developed, the shock front became strongly distorted, showing large scale asymmetry and many small-scale protrusions, as can be seen in the volume rendering of the specific entropy distribution shown on the right.