McWilliams Center for Cosmology-Dept of Physics - Carnegie Mellon University

McWilliams Center for Cosmology


Roy Briere
Rupert Croft
Tiziana Di Matteo
Christos Faloutsos
Christopher Genovese
Fred Gilman
Shirley Ho
Tina Kakhniashvili
Leonard Kisslinger (Emeritus)
Peter Lee
Rachel Mandelbaum
Manfred Paulini
Jeffrey Peterson
Ira Rothstein
James Russ
Chad Schafer
Jeff Schneider
Hy Trac
Adrien Treuille
Helmut Vogel
Larry Wasserman

Center Website:

Group Overview

The McWilliams Center for Cosmology at Carnegie Mellon University joins research efforts in astrophysics and particle physics and partners with computer science, statistics, and other disciplines to unravel the mysteries of the universe. More than 95 percent of the universe is composed of mysterious dark matter and dark energy, about which little is known. Dark matter is thought to play a key role in the formation of galaxies and the clustering of galaxies in the universe. Dark energy is responsible for the accelerating expansion of the universe. The center supports research on the makeup of the universe and how it evolved to its current state, and assists faculty and students engaged in a multidisciplinary quest to advance understanding of the universe.

Faculty Member Research Thrusts

Guy Blelloch (Computer Science) works on parallel algorithms and programming languages. In the area of algorithms, he has worked on algorithms for a variety of problems including meshing, n-body codes, sorting, computational biology, graph problems, and compact data representations. In the area of programming languages, he has worked on developing new language structures for parallelism and techniques for efficiently executing parallel codes.

Roy Briere (Physics) concentrates on precision measurements in weak flavor physics as a means for searching for new physics beyond the current Standard Model. This method is complementary to direct searches for new particles at energy frontier machines. The weak interactions of quarks are currently the only known source of matter-antimatter (CP) symmetry violation, but the preponderance of matter over antimatter in our universe tells us that there must be an additional source of CP violation that is as yet undiscovered. He is also investigating options for making use of his experiences with large high-energy physics datasets by joining one of the new telescopic survey projects.

Rupert Croft's (Physics) main research interests are in computational cosmology, involving both simulations and the analysis of large surveys. He primarily focuses on the physics of the intergalactic medium, its use as a probe of cosmology and of galaxy and quasar formation. He is a member of the SDSS-III survey of galaxies and quasar absorption lines which aims to measure dark energy parameters using large scale baryonic oscillatory features as a standard ruler. Croft also works on the interaction between matter and radiation in the intergalactic medium, on the re-ionization of the Universe, and predictions for future 21cm radio observations of this high redshift cosmological frontier. He makes use of the McWilliams Center’s high performance computing facilities, including Warp, the 700 core cluster to perform cosmological hydrodynamic and radiative transfer simulations.

Tiziana Di Matteo (Physics) is a theorist with expertise in both high energy astrophysics and cosmology. Her recent interests focus on state-of-the-art cosmological simulations of galaxy formation including detailed modeling of the impact of black hold feedback on structure formation. She has consistently been awarded large allocations of time on the largest national computing facilities and also makes use of the computational facilities of the McWilliams Center for Cosmology.

Christos Faloutsos (Computer Science) works on data mining for large datasets. He has been using the idea of fractal dimension to characterize clouds of points in n-dimensional space, the 'hadoop'/mapReduce architecture to handle large datasets, and spectral methods to analyze large graphs.

Christopher Genovese's (Statistics) research involves high-dimensional and nonparametric inferences with applications to complex scientific problems. A major focus of his research is developing statistical methods for problems in astrophysics and cosmology, including analysis of the Cosmic Microwave Background, inference for the dark energy equation of state, and source detection.

Fred Gilman (Physics) does research in theoretical particle physics, particularly in understanding the nature of CP violation. He looks to the LHC to provide us with additional sources of CP violation that would explain the dominance of matter over antimatter in the universe and to produce in the laboratory the particles that make up the dark matter. Gilman is leading efforts to create and expand the McWilliams Center for Cosmology. He is a member of the Board of Directors of the Large Synoptic Survey Telescope Corporation.

Shirley Ho (Physics) Shirley Ho is a cosmologist whose interest ranges from theory to observations, and whose research involves both simulations and analysis of large scale structure surveys such as the Sloan Digital Sky Survey III or of the cosmic microwave background data from Planck HFI and LFI. She primarily works on utilizing the large scale structure and cosmic microwave background to understand the beginning of the Universe, the dark components of the Universe such as dark energy and dark matter and its lighter but equally elusive contents such as neutrinos and the evolution of the Universe. Her recent interest focuses on the use of a standard ruler called Baryon Acoustic Oscillations via various large scale structure tracers, such as the 3D clustering tracer of large scale structure.

Leonard Kisslinger (Physics) does research on the electroweak and QCD phase transitions, which occurred when the temperature of the universe was about 100 Gev and 150 MeV, respectively. He has been investigating the magnetic fields which are produced for possible polarization correlations in the CMB radiation and as seeds for the galactic and extragalactic magnetic fields which have been observed. He has worked on the gravitational waves produced by these phase transitions. Also, in collaboration with experimentalists and theorists at LANL, he has been studying the detection of quark/gluon plasma in RHIC experiments and the very large velocities of pulsars that are produced in a supernova collapse.

Peter Lee (Computer Science, Dept Head) works on programming languages, including programming languages for very large distributed systems. Besides providing administrative support for the Computer Science Department's efforts in collaborative research in computational cosmology, he is interested in applying his language ideas to large-scale data analysis problems in the field.

Rachel Mandelbaum (Physics) Rachel Mandelbaum's research interests are predominantly in the areas of observational cosmology and galaxy studies. This work includes the use of weak gravitational lensing and other analysis techniques, with projects that range from development of improved data analysis methods, to actual application of such methods to existing data. Currently, she is focusing on data from the SDSS (including the ongoing SDSS-III), and is working on upcoming surveys including Hyper-SuprimeCam (HSC) and LSST.

Manfred Paulini (Physics) studies questions connecting particle physics to issues relevant to cosmology. One such question is the predominance of matter over antimatter in the universe, which requires that there is a breaking of the (CP) symmetry between matter and anti-matter in particle physics. As a member of the CDF experiment at Fermilab, Paulini studies the violation of CP symmetry and matter-antimatter oscillations in Bs mesons. Another question concerns the nature of dark matter that makes up about one quarter of the content of the universe. Paulini will search for the production of dark matter particles with the CMS experiment at CERN and will be analyzing the CMS data looking for supersymmetric particles with decay chains that involve the neutralino, a candidate for dark matter.

Jeffrey Peterson's (Physics) group carries out cosmological observations using the 21 cm emission line of neutral hydrogen. The group is involved in projects using existing telescopes to make three dimensional maps of 21 cm emission for redshifts around ten. These maps will be used to study the first stars and their interaction with surrounding gas. The team also designs and builds 21 cm telescopes. In particular, the group is working to build the Cylinder Radio Telescope in Morocco. This 10,000 square meter telescope will map most of the sky at redshifts near one in order to constrain models of Dark Energy.

Ira Rothstein (Physics) works on diverse topics in quantum field theory and general relativity. He focuses on developing field theoretic tools for the purpose of increasing predictive power in complex non-linear field theories, such as QCD and gravity. In the past, he has been particularly interested in developing effective field theory techniques in order to search for new physics in the Yukawa sector of the standard model. Presently he has been concentrating on a recent formalism (NRGR) developed to study binary inspirals and using NRGR to calculate higher order post-Newtonian corrections to these systems for the purpose of building gravity wave templates for LIGO and LISA.

James Russ (Physics) is a particle experimentalist whose work impacts the physics goals of the McWilliams Center through his involvement with the CMS experiment at the Large Hadron Collider and his work on neutrino astronomy as a probe of Active Galactic Nuclei (AGN) over different red-shift ranges. At CMS we have an opportunity to discover evidence of extra dimensions and indications of a brane-world, which would revolutionize cosmology. The neutrino astronomy project offers insight into nature's highest-energy particle sources and is one of the few ways to put experimental limits on models of AGN physics.

Chad Schafer (Statistics) focuses on addressing interference problems in the physical sciences using novel, often computationally-intensive, statistical methods. Projects in astronomy and cosmology include the development of methods for constructing optimally precise confidence regions for cosmological parameters, for estimating bivariate luminosity functions, and for estimating properties of galaxies via low-dimensional representations of their emission spectra.

Jeff Schneider (Robotics Institute) is pursuing active learning for scientific discovery. An active learning algorithm not only learns models from data, but also selects which experiments to run in order to collect the training data. Recent work focused on algorithms that select cosmological parameters for CMBFast runs in order to find those consistent with the WMAP data. This work has been extended to selecting across multiple model/data types (e.g., CMB, supernovae, large scale structure) with varying computational costs. Other current efforts include approaching anomaly detection as an active learning problem and learning dynamic models from static data.

Hy Trac is a theoretical and computational cosmologist whose scientific interests include cosmic evolution and structure formation. His work is generally centered on the development and application of numerical simulations to model and interpret the observable Universe. In cosmology, he is especially interested in complex problems involving the gas, stars, galaxies, quasars, and clusters of galaxies that provide information about the underlying dark matter and dark energy. In astrophysics, he would particularly like to work on star and planet formation and the development of planetary atmospheres. He also collaborates with machine learning experts and statisticians to apply modern approaches to improve multi-wavelength data analysis and numerical simulations. He is a member of the Atacama Cosmology Telescope (ACT), Sloan Digital Sky Survey (SDSS), and Large Synoptic Survey Telescope (LSST) collaborations.

Adrien Treuille (Computer Science) attempts to advance our understanding of very high-dimensional nonlinear phenomena. One thread of his research addresses the complexity of such systems by developing model reduction tools that generate compact representations. A complimentary thread seeks to control such systems. The mathematical techniques that he has developed have been applied to phenomena as diverse as animal morphology, human motion, and large fluid systems.

Helmut Vogel (Physics) does research in high-energy particle physics experiments. For many years, he worked at LEP, the electron-positron colliding-beam accelerator which was the precursor to the LHC at CERN. Among its landmark results were a determination of the number of neutrino families in the universe and the most stringent lower limit to date on the mass of the Higgs boson. Presently, Vogel is a member of the CMS experiment at the LHC where he plans to study muons produced in the proton-proton collisions as probes of both "conventional" and "exotic" physics processes.

Larry Wasserman (Statistics and Machine Learning) does research in nonparametric interference, high-dimensional models, and the development of statistical methods for astrophysics problems such as: estimating the equation of state of dark energy; the analysis of the cosmic microwave background radiation; and filament finding.