1. S. Dodelson is with the NASA/Fermilab Astrophysics Center, Fermi National Acceleator Laboratory, Batavia, IL 60510-0500, USA.
2. E. I. Gates is with the NASA/Fermilab Astrophysics Center, Fermi National Acceleator Laboratory, Batavia, IL 60510-0500, USA, and the Department of Astronomy and Astrophysics, Enrico Fermi Institute, University of Chicago, Chicago, IL 60637-1433, USA.
3. M. S. Turner is with the NASA/Fermilab Astrophysics Center, Fermi National Acceleator Laboratory, Batavia, IL 60510-0500, USA; the Department of Astronomy and Astrophysics, Enrico Fermi Institute, University of Chicago, Chicago, IL 60637-1433, USA; and the Department of Physics, Enrico Fermi Institute, University of Chicago, Chicago, IL 60637-1433, USA.