People

Staff Members

Matt Becker

Matt’s work focuses on multidisciplinary problems related to cosmology, numerical computing, data analysis, statistics, and machine learning. He has worked on a broad range of topics from image analysis for the Dark Energy Survey to the development of multiple-plane ray tracing algorithms for computing weak gravitational lensing signals from N-body simulations. After spending several years in industry working in data science, his interests now include the application of deep generative modeling techniques to problems in computational cosmology and the use of cosmological simulations as tools for statistical inference.

HEP
B360 C217
mrbecker@anl.gov
Lindsey Bleem

Does the accelerating expansion of the universe require a modification to our theories of gravity or does  there exist some new form of energy, so-called ‘Dark Energy?’ Lindsey seeks to answer such questions by studying of clusters of galaxies — the largest gravitationally-bound systems in the universe. Their abundance is a powerful cosmological probe as it depends upon both the expansion history of the universe and the growth of density fluctuations. A member of the South Pole Telescope collaboration, her research interests also include large-scale structure, the cosmic microwave background, and the development of bolometric detectors for measurements of the millimeter-wave sky. Lindsey received her PhD from the University of Chicago in 2013 and BA from Kenyon College in 2005.

HEP
B360 C233
lbleem@anl.gov
Hal Finkel

Hal Finkel graduated from Yale University in 2011 with a Ph.D. in theoretical physics focusing on numerical simulation of early-universe cosmology. He is now the Lead for Compiler Technology and Programming Languages at the ALCF. Hal has contributed to the LLVM compiler infrastructure project for many years and is currently the code owner of the PowerPC backend and the pointer-aliasing-analysis subsystem, among others. He is the lead developer on the bgclang project, which provides LLVM/Clang on the IBM Blue Gene/Q supercomputer, and represents Argonne on the C++ Standards Committee. Hal also helps develop the Hardware/Hybrid Accelerated Cosmology Code (HACC), a two-time IEEE/ACM Gordon Bell Prize finalist. He has designed and implemented a tree-based force evaluation scheme and the I/O subsystem and contributed to many other HACC components.

ALCF
B240 2126
hfinkel@anl.gov
Salman Habib

Aside from being a member of CPAC, Salman Habib also leads Argonne’s Computational Science Division (CPS). He holds joint appointments at the University of Chicago and Northwestern University. Salman’s research interests span astrophysics and cosmology, accelerator physics, classical and quantum dynamical systems and control theory, advanced statistical methods and machine learning, condensed matter physics, atomic and quantum optics, nonequilibrium field theory, and particle physics. Within cosmology, his current focus is on studies of dark energy, dark matter, neutrinos, and primordial fluctuations. This work involves a number of research directions at the interface of cosmological physics, advanced statistical methods, machine learning, and parallel supercomputing. Salman is the PI for the DOE ASCR ExaSky project that is preparing HACC for coming exascale supercomputers; he has led the HACC team since its first incarnation at Los Alamos.

HEP/MCS
B360 C113
habib@anl.gov
Webpage
Andrew Hearin

Andrew’s research interests are at the intersection of cosmology and galaxy formation. He develops techniques to analyze large-scale structure data from present and near-future galaxy surveys aimed at uncovering the physical nature of dark matter and dark energy. Andrew’s focus is on transforming cosmological simulations into synthetic skies of gas and galaxies, so that simulations can be used as direct cosmological inference engines.

HEP
B360 C121
ahearin@anl.gov
Katrin Heitmann

Katrin Heitmann, CPAC Group Leader, is a Physicist and Computational Scientist at Argonne National Laboratory in the High Energy Physics and Mathematics and Computer Science Divisions. She is also a Senior Member of the Kavli Institute for Cosmological Physics at the University of Chicago. Before joining Argonne, Katrin was a staff member at Los Alamos National Laboratory. Her research currently focuses on computational cosmology, in particular on trying to understand the causes for the accelerated expansion of the Universe. She is responsible for large simulation campaigns with HACC and for the tools in the associated analysis library, CosmoTools. Katrin is a member of several major astrophysical surveys that aim to shed light on this question and is the computing coordinator for the Large Synoptic Survey Telescope Dark Energy Science Collaboration.

HEP/MCS
B360 C125
heitmann@anl.gov
Eve Kovacs

Eve’s research interests are focused on understanding the galaxy-halo connection and the simulation and validation of mock galaxy catalogs for upcoming sky surveys such as LSST. She is a member of DES and LSST-DESC. Eve is also interested in supernova cosmology, and in particular, the photometric classification of supernovae using machine-learning techniques.

HEP
B360 L177
kovacs@anl.gov
Adrian Pope

Adrian Pope is a member of Argonne’s CPS Division. He has studied the large-scale structure of the Universe dating back to his work as an undergraduate (and after) on the Sloan Digital Sky Survey. Adrian plays a leading role in the development of HACC, beginning with the initial code prototype that ran on Roadrunner at Los Alamos, the first machine to break the petaflop barrier. He is currently investigating the optimization of HACC kernels on Aurora 2021, planned to be the first exascale system in the US, and expected to arrive at Argonne in 2021. Adrian also has interests in applications of advanced statistical methods in cosmology.

CPS
B240 1123
apope@anl.gov
Thomas Uram

Tom is a software engineer at the ALCF with extensive experience in software projects that involve high performance computing. He is the main developer of Balsam, an HPC workflow and edge service for running a large number of jobs on HPC systems. Tom has a leadership role in software management for HACC’s CosmoTools library; he has also led the work in making simulation data widely available through Argonne’s Petrel Data Pilot project.

ALCF
B240 4141
turam@anl.gov

Postdocs

Jonas Chaves-Montero

Jonas’s research interests are in the field of cosmology, focusing on the study of the distribution of galaxy positions and velocities at large scales and how to use this information to obtain a better understanding of the dark side of the Universe — dark energy and dark matter. In order to do so, he uses theoretical tools and develops numerical simulations to extract unbiased cosmological information from galaxy surveys.

HEP
B360 C129
jchavesmontero@anl.gov
Webpage
JD Emberson

JD has a broad interest in computational cosmology. His research is focused on the development and application of numerical techniques for large-scale cosmological structure formation. This includes both N-body as well as hydrodynamic simulations in order to gain insight into various astrophysical problems including dark energy, neutrinos, substructure, and reionization. Along with Nick Frontiere, he is leading the effort on the new hydrodynamics capability in the HACC code.

HEP/ALCF
B360 C129
jemberson@anl.gov
Webpage
Martina Gerbino

Martina Gerbino is a theoretical cosmologist working at the interface between theory and observations, with a particular focus on testing fundamental physics theories against data. Her research interests span phenomenological investigation of theoretical models with a main focus on neutrino physics to CMB data analysis and interpretation. She is a member of the Planck, Simons Observatory and CMB-S4 collaborations.

HEP
B360
mgerbino@anl.gov
Patricia Larsen

Patricia’s interests focus mainly on measurements of weak lensing in cosmological surveys. In particular she has worked on combining weak lensing measurements of the CMB and cosmic shear, and on understanding astrophysical systematics affecting weak lensing surveys, including galaxy intrinsic alignments.

HEP
B360 C117
prlarsen@anl.gov
Nesar Ramachandra

Nesar Ramachandra is a cosmologist with interests in the dynamics of large-scale structure formation; he is also working on the implementation of state of the art statistical and machine learning methods for cosmological data analysis and fast prediction tools (emulators) as part of the SciDAC-4 project led by CPAC.

HEP
B360
Esteban Rangel

Steve Rangel is a computer scientist with broad interests in solving large-scale data analysis problems using HPC platforms. He is the main developer of HACC’s halo merger tree construction and analysis framework, using a new algorithm that employs the recently developed ‘core-tracking’ methodology. Steve also led work on a new parallel tessellation-based density estimation code that is now being used for work on weak and strong gravitational lensing (with Patricia). Steve is now also working on HACC’s implementation on exascale platforms.

HEP/ALCF
B360 C117
erangel@anl.gov
Malin Renneby

Malin is a computational astrophysicist whose research is focused on how to statistically constrain the galaxy-halo relation through cosmic time with weak lensing and galaxy clustering with semi-analytical models of galaxy formation and hydrodynamical simulations. Specifically she is interested in imprints of baryonic processes such as AGN feedback on halo profiles and clustering amplitudes and strategies to include these high signal-to-noise small-scale signals in joint-probe cosmological parameter inference pipelines.

HEP/ALCF
B360
mrenneby@anl.gov
Antonio Villarreal

Antonio’s research interest lies in better understanding and quantifying the connections between simulations and the phenomenological understanding that can be gleaned from these to the observable universe. This manifests in the study of halo assembly bias as a function of the choice of halo definition, determining how much potential bias in cosmological parameters can arise from underlying dark matter power spectra assumptions, and aiding in the generation of simulated images for future surveys such as the Large Synoptic Survey Telescope.

HEP/ALCF
B360 C129
avillarreal@anl.gov

Students

Hillary Child

Hillary’s research focuses on the evolution of dark matter halos in simulations. She is currently working on measuring the concentrations of simulated halos to better determine the redshift dependence of the concentration-mass relation, and to better understand how the concentration of a halo changes as it grows. She is also working on using the bispectrum to improve measurements of the baryon acoustic oscillations (BAO) length scale.

B360 C145
childh@uchicago.edu
Nicholas Frontiere

Nick has wide interests in physics and computational science. He has worked on computational research projects at National Laboratories for many years. Nick has made many contributions to HACC (in particular the GPU version) and its analysis tools, beginning with work as an undergraduate on the HACC 3-D parallel FFT, now available separately as the DOE ECP-supported SWFFT package. He has played a leading role in the development of a new smoothed particle hydrodynamics (SPH) method, Conservative Reproducing Kernel SPH (CRK-SPH), that overcomes many of the problems of the original SPH technique, while maintaining many of its advantages. Nick is leading the work on the hydro version of the HACC code (with JD) and in the incorporation of a number of subgrid models.

B360 C129
nfrontiere@anl.gov
Joe Hollowed

Joe is currently working with the group at the post-baccalaureate level, contributing to the construction of synthetic galaxy catalogs, and providing simulation support for cluster cosmology studies. He has active pursuits in SPT and LSST DESC, and also has broad interest in investigating the nature of the Universe at large scales via a computational approach — from the details of cluster physics to large-scale structure formation and cosmological expansion.

B360 C145
jphollowed@anl.gov
Webpage
Dan Korytov

Dan’s research interest is on the connection between galaxies and dark matter halos. In particular, he is leading a novel method of determining galaxy positions by explicitly tracking simulation particles (‘core-tracking’). This method does not suffer from the difficulty of identifying substructure or numerical disruption of substructure. He is also heavily involved with the production the main synthetic galaxy catalog for the LSST DESC collaboration.

B360 C145
dkorytov@uchicago.edu
Xin Liu

Xin is a starting graduate student in CPAC. She is generally interested in computational cosmology. In particular, her main focus at the moment lies in using simulation and data analysis as tools to help her get a deeper understanding of cosmological problems.

B360
xinliu8@uchicago.edu
Gabe Lynch

Gabe’s research interests are varied, but range from the conditions of the very early universe to the physics of structure formation. His research focuses on how primordial fluctuations, baryonic physics, and different models of dark matter may each explain the missing satellite problem and other shortcomings of LCDM. He is also interested in tests that may distinguish those models, from those that are cosmological in scale down to laboratory experiments.

B360
gplynch@uchicago.edu

Administration

Samantha Tezak

Samantha is responsible for keeping CPAC running, in particular, all the main administrative tasks, including travel, purchase requests, various Argonne requirements, and supporting CPAC visitors. She is also responsible for helping to organize meetings and workshops, and maintaining the associated websites.

Administrative Secretary
High Energy Physics Division
Argonne National Laboratory
9700 S. Cass Avenue
Bldg. 360
Argonne, IL 60439

B360 C133
stezak@anl.gov