I am a theoretical astrophysicist, at TAPIR at Caltech, and part of the Moore Center for Theoretical Cosmology and Physics and Walter Burke Institute for Theoretical Physics. I’m also the leader of the FIRE project.

I have the good fortune to be working on a diverse array of questions related to planet, galaxy, star, and black hole formation and evolution.

This is work with a large number of collaborators: check my Welcome page for links to their home pages.

Some questions we ask include: How do stars, black holes, and galaxies form? What is the nature and impact of “feedback" from quasars and massive stars (as they accrete and explode) on the galaxies they live in, and subsequent generations of star and black hole growth? What happens when galaxies collide? How can we relate seemingly diverse populations: quasars, starbursts, ultra-luminous galaxies, red/elliptical galaxies, galaxy mergers, star clusters, and more? How do planets actually form — are there formation scenarios that didn’t happen in our solar system but appear in the new worlds we’re discovering?

Interested in working with our group? See the opportunities listed on the Welcome page!

Animations and Explanations of some of our Work:

Movies of isolated galaxies with powerful outflows driven by supernovae and other forms of feedback from young, massive stars

Movies of galaxy mergers between those same galaxies 

Movies of galaxy merger simulations with outflows driven by accreting black holes instead of massive stars

Movies of “Zoom-In” simulations that follow gas from a merger down to ~0.1 parsec scales as it accretes onto a super-massive black hole

Movies of cosmological simulations, where we follow the formation of galaxies over cosmic time, with powerful outflows driven by feedback

Movies of a fly-through of a Milky-Way like galaxy, formed in cosmological simulations, showing various properties

For a simple archive of all the movies above (and others), go to

See our Press page for links to popular articles, describing our work for general audiences

And for more recent updates, and links to movies on other sites, check my blog

Links to Learn More:


Conference Proceedings, Talks, & Colloquia

Curriculum Vitae

Some advice and useful links for students who want to get started studying star and galaxy formation

The FIRE Project: Our current massive collaboration to study galaxy formation

Simulation Codes we’ve developed:

Our new multi-physics (magneto-hydrodynamics + gravity) code, GIZMO, is described on this site (here)

A public version of the cosmological simulation code, GADGET, from Volker Springel, is available here.

Pressure-Entropy SPH (P-SPH):

From a 2012 paper “A General Class of Lagrangian Smoothed Particle Hydrodynamics Methods and Implications for Fluid Mixing Problems,” available at:

We discuss the fact that there are some known subtle problems with the treatment of fluid discontinuities in “standard” SPH prescriptions such as GADGET. We introduce instead the Lagrangian “Pressure-Entropy” formulation of the SPH equations which removes the problematic “surface tension force” and so substantially improves the treatment of fluid mixing and contact discontinuities.

A public version of this algorithm, implemented in the public version of GADGET-2, is available for download from this website (gadget2p.tgz) and/or from the astro-code Wiki here

Numerous code comparisons between this and ‘standard’ SPH are shown in the paper. But for a quick example, compare a movie (made very simply from an extremely low-resolution simulation) of the Kelvin-Helmholtz instability in ‘standard’ SPH and ‘pressure-entropy’ SPH

Because of some proprietary conflicts, the full version of GADGET used to run some of the simulations shown here (which has been very extensively modified from GADGET-2 and GADGET-3) is not currently public. But please email me if you’d like to discuss obtaining a copy of the code.

Other Public Data, Tables, & Routines: 

  Bolometric Quasar Luminosity Function :

   (Hopkins, Richards, & Hernquist, 2006)

  Galaxy (and Halo) Merger Rates :

   (Hopkins, Bundy, Croton et al., 2009)

© Philip Hopkins 2015