Three-dimensional picture of the distribution of matter in the universe. (Credit: HSC Survey)
Research directions of the Center include theoretical astrophysics, with emphasis on computation and simulation; experimental astrophysics, with emphasis on the dark part of the universe and data mining; and particle physics, especially as related to the search for and theoretical understanding of dark matter particles at the LHC.
Astrostatistics is concerned with developing statistical techniques for the analysis of astrophysical data. Carnegie Mellon has a unique established group of researchers in astrostatistics who have tackled a wide range of astrophysical problems. Recent research topics include: analysis of the Cosmic Microwave Background, estimating the dark energy equation of state, analysis of galaxy spectra, detecting galaxy clusters via the Sunyaev-Zeldovich effect, identifying filaments, and estimating density functions with truncated data. A common theme in this work is the goal of detecting subtle, nonlinear signals in noisy, high-dimensional data. The group plans to be deeply involved in future large surveys such as the LSST.
As petascale computing becomes a mainstay in many fields of scientific research, Computer Science researchers at Carnegie Mellon aim to develop the software, architectures, and community expertise to use these machines optimally. Emerging advances in multiscale modeling, simulation machine learning, data mining, and visualization can be exploited at the petascale for future scientific discovery. In particular, research focuses on developing data-intensive scalable computing (DISC) architectures and algorithms for managing and serving scientific data and computations to potentially very large user bases; developing scalable algorithms, data mining, and machine learning techniques for analyzing and gaining knowledge from massive amounts of data such as those to be gathered by the LSST; and developing the tools for doing cutting-edge numerical numerical simulations relevant to cosmology.
From the study of the earliest energy emission in the universe ‒ the Cosmic Microwave Background Radiation ‒ to the smallest dwarf galaxies and the formation of the large-scale structure, McWilliams Center researchers are part of the worldwide scientific quest to determine the basic cosmological parameters, investigate the nature of dark matter and dark energy, and describe and understand the evolution of individual galaxies and the universe as a whole. This research will greatly benefit from large data sets produced by current and planned ground-based and space-based observatories. Carnegie Mellon participates in multiple large sky surveys and has joined the Large Synoptic Survey Telescope Corporation and become a member of the Association of Universities for Research in Astronomy (AURA), which is building the LSST as the premier ground-based survey telescope when it starts operations in 2022. The analyses of these data sets are very challenging and will require both the development of highly sophisticated simulations and the application of the latest tools in data-mining, statistics, and machine learning. Carnegie Mellon is partnering as well to build and use mapping of the 21 cm radiation from neutral Hydrogen to explore the universe and particularly to understand the nature of dark energy.
Theoretical astrophysics research carried out at the Center focuses on the formation of structure in the universe and the role played by dark matter and dark energy. Large scale cosmological simulations are used as a tool to investigate the formation of galaxies and the growth and evolution of their associated super-massive black holes. The material in between galaxies is also an active area of study, as it contains the gas from which future stars will form. As we look back in time to the so called "dark ages" before the first stars formed, all these topics converge, and important roles are played by the first black holes, earliest galaxies and intergalactic gas in the re-ionization of the universe. This epoch is just beyond the current observational frontier, and theoretical predictions are being made for what will be seen, work made possible by the development of petascale simulation algorithms and physical modeling at the McWilliams Center. The Center's dedicated computer cluster, Ferrari, and the Moore supercomputer shared with Computer Science will be important facilities in carrying out this research.
Theoretical Particle Physics
The LHC (Large Hadron Collider) will produce collisions of protons at energies never before reached. The products of these collisions could very well include the dark matter particles that compose twenty-three percent of the mass-energy in the universe. Indeed, there are compelling arguments that the energies at which the LHC operates are exactly in the window to see Weakly Interacting Massive Particles (WIMPs). The remarkably successful Standard Model (SM) of particle physics however, does not include WIMPs, or any other realistic dark matter candidate. With data soon to come from the LHC, theorists in the Center will be part of the world-wide challenge to extend the SM in a way which is consistent with both the mathematics of quantum field theory and the bounds arising from laboratory experiments and cosmological observations. In particular, the discovery of a dark matter candidate would allow us to study its properties in a laboratory setting and, together with theoretical insights, to develop an underlying theory that encompasses both the SM and the new physics that includes dark matter.
Experimental Particle Physics
Carnegie Mellon is a member of the international collaboration that built and operates the Compact Muon Solenoid (CMS), one of the two major detectors at the Large Hadron Collider (LHC). Carnegie Mellon physicists constructed the state-of-the-art electronics, consisting of 150,000 channels, for the end-cap muon detectors of CMS. While so far unsuccessful at total proton-proton collision energies up to 8 TeV, a prime experimental activity at the LHC as it operates at higher collision energies will be searches for the production of the particles that make up some or all of the dark matter observed in the cosmos. For example, a widely-studied candidate for the dark matter particles is the neutralino, if it is the lightest and most stable of a set of new supersymmetric partners to each of the particles of the Standard Model. Experimental particle physicists in the Center will be searching the CMS data for evidence of the neutralino or other possible dark matter particles, and then studying their properties if they are found. Astroparticle experiments looking for either indirect evidence of the annihilation of dark matter particles in the cosmos or direct evidence of dark matter particles interacting with ordinary matter in cryogenic experiments deep underground are possible areas for future involvement of physicists in the McWilliams Center.