Chung-Pei Ma Professor of Astronomy Ph.D. (Physics) 1993 Massachusetts Institute of Technology Official Website Office: 641B Campbell Hall Phone: (510) 642-4850 Fax: (510) 642-3411 Email: cpma AT berkeley.edu

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Research Interests: Ma's scientific work has been on theoretical problems in cosmology with ties to observations. Four personae have been diagnosed for her multiple personality syndrome, although her graduate students (see below) 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 I have 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. I have been involved in designing and running large numerical N-body and hydrodynamical codes to simulate and study the nonlinear growth of dark matter and baryons. Lately my interests are in developing new analytical techniques to better understand and model the nonlinear structure in the universe. The questions I am tackling include the phase-space evolution of galaxy host halos and the origin of their density profiles. This has led me into the deep trenches of the 90-year-old Fokker-Planck and dissipation-fluctuation theories. The Dark Side: The nature of dark matter remains one of the most intriguing unsolved mysteries in astronomy. My interest has evolved from cold, to hot, to warm, and back to cold (but never lukewarm) dark matter, and has recently extended to the "dark energy." Our investigations involve making detailed theoretical predictions for the impact of dark matter and energy on structure formation. By comparing these with observational results from, e.g., the high redshift universe and gravitational lenses, we can obtain constraints on the nature and abundance of dark matter and energy. The Bright Side: I occasionally manage to climb out of the dark and lumpy worlds. During these sunny moments (or rather, moonless nights), I have collaborated with observers on a number of projects using telescopes at Palomar and Keck. These have included dynamical studies of superclusters, surveys of intermediate redshift galaxies, gravitational lensing studies of quasars and galaxy clusters, and properties of redshift 1 galaxies.

Recent Research Results: Latest papers on red galaxy mergers by Boylan-Kolchin, Ma, and Quataert: 2005, 2006a, 2006b Are Collisionless Cold Dark Matter Halos Collisionless? by C.-P. Ma and M. Boylan-Kolchin (2004), Physical Review Letters , 93 , 021301. A Cosmological Kinetic Theory for the Evolution of Cold Dark Matter Halos with Substructure: Quasi-Linear Theory by C.-P. Ma and E. Bertschinger (2004), Astrophysical Journal , 612 , 28. Below are a movie and five snapshots (from our simulation) and two images (from earlier work by B. Moore and Jing & Suto), showing how small lumpy dark matter halos coexist and interact with big parent halos. Ed Bertschinger and I have derived a kinetic theory based on cosmological perturbations of current standard model to describe this intriguing and interesting process. The equation we found at the end of our calculation has a similar form as the equation for the Brownian motion of pollen particles suspended in a fluid first written down 90 years ago by Fokker and Planck. A similar equation is also used by some economists to calculate the asset price fluctuations in the market. Cosmic structures, molecules, and money have something in common after all. Watch the Brownian motion! (Warning: This product may cause drowziness.) Our Dark Matter Halo Formation Movie (mpeg format ; should be OK for Mac) (avi format) (After clicking here, the screen may appear completely white after loading. Simply click on any part of white screen to start the movie.) A Higher-Resolution Version of the Movie (avi) Movie Snapshot 1 , 2 , 3 , 4 , 5 Candidate "Local Group" from simulations by B. Moore et al. (2001), Physical Review D64, 063508 12 Simulated Halos from Jing and Suto (2000), Astrophysical Journal, 529, L69 Is dark matter profile really "universal"? Here is its checkered history

The Team: See our academic genealogy (2/3 way down the page). It goes back to 1822 and includes Fowler, Chandrasekhar, Wien, and Helmholtz. The tree started in Cambridge UK and Germany and migrated westward to Columbia/MIT/Princeton/Chicago then to California. You must obey these three laws to join the group. Some party photos: 2005, 2006. Ever wondered what astronomers actually do on an observing trip? Some action photos.

Graduate students to keep off the street: Onsi Fakhouri (astro, 5th yr) Jackson DeBuhr (physics, 4th yr) Jonathan Blazek (physics, 2nd yr) You? (come and chat)

Former and other diligent students who brighten my days or eat cookies at group meetings: Michael Boylan-Kolchin (PhD 2006, postdoc at Max-Planck Institute) Alison Coil Julie Comerford Jeff Filippini Brad Hagan Evan Levine David Rusin (Penn) Shwetabh Singh (Penn) Nick Sarbu (Penn)

Postdocs to wine and dine: Tzu-Ching Chang TAC Fellow (Columbia PhD 2003, postdoc at CITA) Alice Shapley Miller Fellow (Caltech PhD 2003 Princeton/UCLA Prof 2005-) Jun Zhang TAC Fellow (Columbia PhD 2006)

Teaching: Astro 3: Descriptive Cosmology (Fall 2008) Astro 84: Sophomore Seminar (Fall 2007) Phys/Astro 161: Relativistic Astrophysics and Cosmology (Spring 2007) Phys/Astro 228: Extragalactic Astronomy and Cosmology (Fall 2006) Astro 292: Current Research in Cosmology and Extragalactic Astronomy (Spring 2005) Astro 250: Advanced Topics in Modern Cosmology (Spring 2004)

Articles: The Economist: "Seeing in the dark" Nature: science update "Dark matter doesn't move in mysterious ways" SPACE.com: "Dark matter exposed" Berkeleyan: "Dark matter forms a ghost universe" ScienceMatters "When galaxies collide", "The mysterious matter of dark matter" UCB NewsCenter: In my past life I studied violin performance at the New England Conservatory of Music. My teachers have included Masuko Ushioda, Lucy Stoltzman, and Stephanie Chase. Occasionally I go to wild music parties like these.