You must obey these three laws to join the group.


Chung-Pei's scientific work has been on theoretical and observational problems in extragalactic astronomy and cosmology. Four personae have been diagnosed for her multiple personality syndrome, although her graduate students and postdocs may report (and have induced) more identities:

  • The Smooth Side: During the first ten million years or so after the big bang, the fluctuations in matter and radiation in the universe remain small enough that they can be viewed as tiny ripples imprinted on a smooth background. The universe at this stage is well described by the linear cosmological perturbation theory, which Chung-Pei has investigated in some depth. This theory is specified by the coupled Einstein, Boltzmann, and fluid equations and is the foundation for many calculations in cosmology, e.g., the matter fluctuation power spectra and the temperature variations imprinted on the cosmic microwave background.

  • The Lumpy Side: A major challenge in theoretical cosmology today is in understanding how small initial fluctuations in matter and radiation in the smooth universe grow under gravitational instability into highly collapsed objects in the lumpy universe. Chung-Pei has been involved in designing and running large numerical N-body and hydrodynamical codes to simulate and study the nonlinear growth of dark matter and galaxies. She has developed new analytical techniques to better understand and model the nonlinear structure in the universe, including the halo model, kinetic theory for halo formation, and non-Markovian extension of the excursion set theory.

  • The Dark Side: The nature of dark matter remains one of the most intriguing unsolved mysteries in astronomy. Chung-Pei's interest has evolved from cold, to hot, to warm, and back to cold (but never lukewarm) dark matter, and has extended to dark energy. She makes detailed theoretical predictions for the impact of the dark sector on structure formation, and obtains constraints on the nature and abundance of dark matter and energy by comparing theory with observational results from, e.g., the high redshift universe and gravitational lenses.

  • The Bright Side: Chung-Pei has participated in a number of projects using telescopes such as Palomar and Keck. The projects include dynamical studies of superclusters, gravitational lensing studies of quasars and galaxy clusters, properties of distant galaxies, and weighing supermassive black holes. She is currently conducting an exciting survey named MASSIVE to study the most massive galaxies in the local universe.

    Graduate Students (to keep off the street)


    • Melanie Veale
    • Irina Ene
    • Matthew Quenneville
    • You? Come and chat

    Postdocs (to dine and wine)


    • Peter Behroozi (Hubble Fellow; Stanford PhD 2012)
    • Freeke van de Voort (TAC-ASIAA Fellow; Leiden PhD 2012)

    Former Team Members (and other diligent students who brightened my days or ate cookies at group meetings)


    • Nicholas McConnell (PhD 2012; Plaskett Postdoc Fellow, NRC Canada, Herzberg)
    • Jackson DeBuhr (PhD 2012; CREST Research Associate, U Indiana)
    • Claude-Andre Faucher-Giguere (Miller Fellow 2010-2013; Northwestern Assistant Professor)
    • Jaime Forero-Romero (Gruber Fellow 2011-2012; Universidad de los Andes Colombia Associate Professor)
    • Dusan Keres (Hubble Fellow 2010-2012; UCSD Associate Professor)
    • Shelley Wright (Hubble Fellow 2009-2012; UCSD Assistant Professor)
    • Phillip Zukin (TAC-ASIAA Fellow; MIT PhD 2012; Search and Data Mining Engineer, Yelp)
    • Genevieve Graves (Miller Fellow 2009-2012; Co-Founder, hiQ Labs)
    • Kevin Bundy (Hubble Fellow 2008-2011; IPMU Assistant Professor)
    • Onsi Fakhouri (PhD 2010; Vice President of Cloud R&D at Pivotal Labs)
    • Michael Boylan-Kolchin (PhD 2006; UT Austin Assistant Professor)
    • Jun Zhang (TAC Fellow 2006-2009; Shanghai Jiao Tong University Associate Professor)
    • Tzu-Ching Chang (TAC Fellow 2003-2006; JPL Research Scientist)
    • Alice Shapley (Miller Fellow 2003-2005; UCLA Professor)
    • James McBride (Senior Thesis 2009)
    • Brad Hagan
    • David Rusin (UPenn)
    • Shwetabh Singh (UPenn)
    • Nick Sarbu (UPenn)