The Cold Dark Matter (CDM) paradigm for the formation of structure in the universe has had many successes, from predicting the spectrum of fluctuations in the Cosmic Microwave Background to explaining the clustering of galaxies. But CDM theory is still at odds with the observed properties of galaxies on scales where the baryonic physics of gas cooling, star formation and feedback are important. Modeling these processes in the cosmological context is extremely difficult owing to the immense dynamic range and resolution needed, and requires the most advanced computational hardware available as well as new computing techniques and algorithms. The proposing team has developed smooth-particle hydrodynamics (SPH) codes addressing these processes at the galaxy scale, and plans to adapt their algorithms to new architectures in order extend them to cosmological volumes. In addition to moving their star formation and feedback algorithms from legacy message-passing interface (MPI) codes to a parallel language (CHARM++), they intend to implement faster algorithms that can achieve the needed dynamic range and take full advantage of the hundreds of thousands of processing cores on the Blue Waters system. The results will be processed by a parallel pipeline that creates simulated observations. The simulations will also be used in a program targeting science pre-majors from under-represented groups, introducing them to the use of computer simulations in astrophysics and encouraging them toward technically oriented majors.
