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| Peter Behroozi | |
|---|---|
| Name | Peter Behroozi |
| Birth place | Tehran, Iran |
| Occupation | Astrophysicist, Cosmologist, Data Scientist |
| Employer | University of California, Santa Cruz |
| Known for | Galaxy formation modeling, UniverseMachine, halo–galaxy connection |
Peter Behroozi is an astrophysicist and cosmologist known for quantitative models that connect dark matter halo assembly to galaxy formation across cosmic time. His work emphasizes open data, statistical inference, and simulation-based modeling to interpret large-scale structure surveys and numerical simulations. Behroozi has developed widely used tools and public catalogs that are foundational to research linking observational programs and theoretical predictions.
Behroozi was born in Tehran and later emigrated to North America, where he pursued undergraduate and graduate studies in physics and astronomy. He completed undergraduate coursework at institutions with active programs in astrophysics, followed by doctoral training that combined computational astrophysics and observational cosmology. His graduate mentorship and postdoctoral training involved collaborations with researchers affiliated with the California Institute of Technology, Princeton University, Harvard–Smithsonian Center for Astrophysics, and national laboratories such as Lawrence Berkeley National Laboratory and Los Alamos National Laboratory. During formative years he engaged with survey projects and simulation consortia connected to the Sloan Digital Sky Survey, Hubble Space Telescope, and theoretical efforts tied to the Millennium Simulation and the IllustrisTNG collaboration.
Behroozi holds academic appointments and research affiliations at institutions known for observational cosmology and computational astrophysics. His faculty and research positions have involved work at the University of California, Santa Cruz, collaborations with the Kavli Institute for the Physics and Mathematics of the Universe, and visiting engagements with groups at the Max Planck Institute for Astrophysics and the Institute for Advanced Study. He leads research programs that interface with teams behind the Dark Energy Survey, Large Synoptic Survey Telescope (now Vera C. Rubin Observatory), and space missions such as the James Webb Space Telescope and the Nancy Grace Roman Space Telescope. Behroozi’s career integrates simulation pipelines, halo catalogs, and empirical modeling frameworks developed alongside groups from the Flatiron Institute, the Center for Computational Astrophysics, and the National Radio Astronomy Observatory.
Behroozi developed empirical models that map galaxy properties onto dark matter halo assembly histories, producing predictive frameworks for galaxy stellar mass growth, star formation rates, and quenching across redshift. His flagship project, the UniverseMachine, generates self-consistent galaxy populations by coupling halo merger trees from N-body simulations such as MultiDark and the Bolshoi simulation to parameterized star formation histories. This work has been applied to interpret results from the Sloan Digital Sky Survey, COSMOS, CANDELS, and deep-field programs conducted with the Hubble Space Telescope and Spitzer Space Telescope. Behroozi’s methodology employs statistical techniques related to Bayesian inference and likelihood-free methods developed in parallel with researchers at the Institute for Computational Cosmology and groups working on the Cosmic Microwave Background analyses from Planck and WMAP.
He has produced extensive public catalogs and halo–galaxy connection tools used by investigators studying galaxy clustering, weak gravitational lensing, and the halo occupation distribution as measured by surveys like the Kilo-Degree Survey, Hyper Suprime-Cam, and the Dark Energy Spectroscopic Instrument. Behroozi’s analyses have clarified tensions between abundance matching, semi-analytic models from groups such as the Munich group and the Santa Cruz SAM team, and hydrodynamical simulations including EAGLE and IllustrisTNG. His work has also influenced efforts to forecast survey yields for the Euclid mission and the Wide Field Infrared Survey Telescope planning consortia.
Behroozi has received recognition from professional societies and funding agencies for contributions to computational astrophysics and open-data science. Honors include invited lectures at conferences organized by the American Astronomical Society, prizes and fellowships affiliated with agencies such as the National Science Foundation and the NASA Astrophysics Division, and selections for topical program leadership at institutes including the Kavli Institute for Cosmology and the National Academy of Sciences–sponsored workshops. He has been invited to present keynote and plenary talks at meetings like the Cosmic Structure Formation symposium, the IAU General Assembly, and the AAS Meeting.
Behroozi’s publications span methodological papers, empirical constraints on galaxy assembly, and public data releases. Notable works include papers describing the UniverseMachine framework and its applications to stellar mass–halo mass relations, star formation histories, and merger-driven growth. His data resources include mock catalogs and halo merger trees built from simulations such as Bolshoi-Planck and MultiDark, and software tools released for community use. Collaborators on these projects have included researchers linked to the Flatiron Institute, the Princeton Center for Theoretical Science, and the Harvard-Smithsonian Center for Astrophysics.
Representative publications and resources (author lists abridged): peer-reviewed articles presenting halo–galaxy connection models; empirical star formation rate reconstructions applied to datasets from SDSS, CANDELS, and COSMOS; and open-source code repositories used by analysts preparing mock survey forecasts for LSST/Rubin Observatory and the Roman Space Telescope. His data releases are widely cited by teams working on galaxy evolution, cluster cosmology, and large-scale structure, including studies carried out within consortia such as DESI and Euclid Consortium.
Category:Astrophysicists Category:Cosmologists Category:University of California faculty