Faculty Research Summaries | Chairman's Introduction

• John E. Carlstrom, Professor, Department of Astronomy and Astrophysics, Enrico Fermi Institute, and the College; Director, Center for Astrophysical Research in Antarctica
• James W. Cronin, Professor, Departments of Astronomy and Astrophysics, and Physics, Enrico Fermi Institute, and the College
• Kyle M. Cudworth, Associate Professor, Department of Astronomy and Astrophysics; Assistant Chairman for Academic Affairs, Department of Astronomy and Astrophysics
• Scott Dodelson, Assistant Professor, Department of Astronomy and Astrophysics and the College
• Douglas Duncan, Associate Professor, Department of Astronomy and Astrophysics; National Education Coordinator, American Astronomical Society
  
• Joshua A. Frieman, Associate Professor, Department of Astronomy and Astrophysics; Head, Theoretical Astrophysics Group, Fermi National Accelerator Laboratory
• Doyal A. Harper, Jr., Professor, Department of Astronomy and Astrophysics and the College
• Roger H. Hildebrand, Samuel K. Allison Distinguished Service Professor Emeritus, Departments of Physics and Astronomy and Astrophysics, Enrico Fermi Institute, and the College
• Lewis M. Hobbs, Professor, Department of Astronomy and Astrophysics and the College
• Stephen M. Kent, Associate Professor, Department of Astronomy and Astrophysics, and the College; Head, Experimental Astrophysics Group, Fermi National Accelerator Laboratory
• Edward J. Kibblewhite, Professor, Department of Astronomy and Astrophysics, and Enrico Fermi Institute
• Edward W. Kolb, Professor, Department of Astronomy and Astrophysics, Enrico Fermi Institute, and the College
• Arieh Königl, Professor, Department of Astronomy and Astrophysics and Enrico Fermi Institute
• Richard G. Kron, Professor, Department of Astronomy and Astrophysics and the College; Director, Yerkes Observatory
• Don Q. Lamb, Jr., Professor, Department of Astronomy and Astrophysics, Enrico Fermi Institute, and the College
• Stephan Meyer, Professor, Departments of Astronomy and Astrophysics, and Physics, Enrico Fermi Institute, and the College; Associate Director, Center for Astrophysical Research in Antarctica
• Richard H. Miller, Associate Professor, Emeritus Department of Astronomy and Astrophysics
• Takeshi Oka, Robert A. Millikan Distinguished Service Professor, Departments of Chemistry, and Astronomy and Astrophysics, Enrico Fermi Institute, and the College
• Angela Olinto, Assistant Professor, Department of Astronomy and Astrophysics and Enrico Fermi Institute
• Patrick E. Palmer, Professor, Department of Astronomy and Astrophysics and the College
• Robert Rosner, William E. Wrather Distinguished Service Professor, Department of Astronomy and Astrophysics, Enrico Fermi Institute, and the College
• Noel M. Swerdlow, Professor, Departments of Astronomy and Astrophysics, and History, Committee on the Conceptual Foundations of Science, and the College
• James W. Truran, Professor, Department of Astronomy and Astrophysics, Enrico Fermi Institute, and the College
• Michael S. Turner, Bruce V. Rauner Distinguished Service Professor, Departments of Astronomy and Astrophysics, and Physics, Enrico Fermi Institute, and the College, Chairman Department of Astronomy & Astrophysics
• Peter O. Vandervoort, Professor, Department of Astronomy and Astrophysics and the College
• Donald G. York, Horace B. Horton Professor of Astronomy and Astrophysics, Department of Astronomy and Astrophysics, Enrico Fermi Institute, and the College

John E. Carlstrom

Questions on the origins of solar-like stars and planetary systems and on the origins of structure in the universe are both being pursued with new observational techniques and instrumentation. We are using interferometric techniques to enable detailed imaging of the cosmic microwave background which has been scattered by hot gas associated with clusters of galaxies, the Sunyaev Zel'dovich effect. Combining these measurements with x-ray observations allows an independent determination of the expansion history of the universe, as well as detailed information about these extremely large structures. A major expansion of this project, which includes building a dedicated ten element array of telescopes has been proposed. We are also finishing a novel new interferometric array to image the anisotropy in the cosmic microwave background radiation; the Degree Angular Scale Interferometer (DASI) will be finished this year and deployed to the South Pole where it will observe year round.

We are also using interferometric techniques to study the role of magnetic fields in the formation of nearby, young solar-like stars and their protoplanetary disks. The high resolution observations are enabled by a unique polarimetric system installed on the OVRO mm-wave array.

James W. Cronin

See Department of Physics

Kyle M. Cudworth

Studies of star clusters are fundamental to several areas of modern astrophysics: stellar evolution, Galactic structure and evolution, stellar dynamics, and the calibration of the astronomical distance scale. We are using astrometric and photometric observations to obtain high precision, clean, color-magnitude diagrams for stars in globular clusters, old open clusters, and some nearby galaxies. In several cases, stellar dynamics within a cluster can be explored in detail. Distances to globular clusters are being obtained via a new method totally independent of previous techniques. Tangential velocities of the most distant clusters associated with our Galaxy are being measured to better determine the mass of the Galaxy.

Scott Dodelson

I am interested in cosmology, in particular in the broad question of how structure formed in the universe. This question is rich not only because it is fascinating in of itself, and not only because there is much data being taken that sheds light on it, but also because it touches so many issues in astrophysics and particle physics. How do galaxies form? Is there dark, non-baryonic matter? What is it? Will the universe continue to expand forever? Did the universe expand exponentially at some early phase in its history? If so, what is the particle physics responsible for this period of inflationary expansion? These are all remarkable questions; even more remarkable is the very real hope that we will be able to answer them in the coming decade.

I believe there are three ways theoretical cosmologists can help answer these and other questions in the general field of structure formation. First, we can introduce new theories or models of how structure formed. This is especially important at present since one general model -- cold dark matter and its variants -- so dominates the theoretical landscape. Second, we can calculate the predictions of existing theories. Finally, we can analyze the plethora of data that is coming in and will be coming in over the next decade. I am interested in all three of these areas, find them stimulating, and hope to work in all of them in the coming years.

Douglas Duncan

Douglas Duncan is a stellar spectroscopist whose interests include the origin and early evolution of the sun and similar stars, optical and ultraviolet spectroscopy of very old stars as a probe of galactic formation and cosmology, and science education. He was part of a group which discovered analogues of the 11-year sunspot cycle on other stars, and continues to study the factors that influence their spots and active regions, chromospheric emission, and coronal X-rays. Most recently, he has been using the Hubble Space Telescope to study to oldest stars in the galaxy, tracing the origin of the chemical elements from the Big Bang down to the present day. This research has provided strong support for the theory of the hot Big Bang, and constraints on supernovae and energetic particle production during the life of the galaxy. Duncan is also very active in the field of science education, and serves as the National Education Coordinator of the American Astronomical Society.

Joshua A. Frieman

Frieman's primary research is in cosmology, especially the formation of large-scale structure and the interplay between cosmology, particle physics, and astrophysics. Current research interests include the analysis of large-scale structure in galaxy surveys such as the Sloan Digital Sky Survey, and the use of weak gravitational lensing observations to probe the distribution of mass on large scales. Frieman is Head of the Theoretical Astrophysics group at Fermilab, which has close connections with the cosmologists and theoretical astrophysicists at Chicago.

Doyal A. Harper, Jr.

My research group uses infrared and submillimeter techniques to study processes related to the formation and evolution of stars, planetary systems, and galaxies. Work in progress includes observations of proto-planetary disks around main-sequence stars like Vega and Beta Pictoris; studies of cold, compact, protostellar objects in the cores of dense interstellar clouds; and observations of galaxies in which intense bursts of star formation result in infrared luminosities many times greater than their luminosities in the visible regions of the spectrum.

Roger H. Hildebrand

See Department of Physics

L. M. Hobbs

Spectroscopic observations of the light elements lithium, beryllium, and boron in Galactic stars of all ages are being used to investigate the nucleosynthetic origin of these elements, both in the Big Bang and in processes that occurred much later in our Galaxy. The inferred abundances of these elements, including the two isotopic forms of lithium, pose fascinating questions about stellar structure, the chemical evolution of the Galaxy, and the early Universe. In particular, the lithium data are vitally important in empirically evaluating the properties of the Universe at a few minutes after the Big Bang.

The Hubble Space Telescope is being used to study the spectrum of the very nearby star Beta Pictoris. Strong absorption is found by gas orbiting in a solar-system-sized disk that surrounds this relatively young star; small dust particles also were previously discovered in the disk by a number of other investigators. The time-varying gaseous absorption and the organization of the dust suggest that the disk may harbor a large number of comet-like bodies, and possibly even two or more planets.

In a separate program, the Hubble Space Telescope is being used to determine the spatial distribution, motions, and physical properties of individual clouds of tenuous interstellar gas in the general neighborhood of the Sun. Included are a few clouds moving toward the Sun at high speeds which apparently were ejected in relatively recent supernova explosions. The combination of the HST and its high-resolution spectrograph allows unprecedentedly precise and detailed studies of this kind.

Stephen M. Kent

Stephen Kent continues as computing coordinator for the Sloan Digital Sky Survey and has overall responsibility for data acquisition and data processing software for that project. He is additionally involved in various aspects of project management, telescope optics, and commissioning the telescope and imaging instruments. He is also head of the Experimental Astrophysics Group at Fermilab.

Edward J. Kibblewhite

My current research focuses on developing new techniques to achieve diffraction-limited imaging in fully filled apertures and distributed arrays of telescopes. The full resolution of ground-based telescopes will be achieved at near infrared wavelengths using a laser beam to generate an artificial star in the sodium layer of the earth's atmosphere. This star will enable the instantaneous wavefront of the atmosphere to be measured and these data used to correct for the atmospheric distortion using adaptive optics and post processing of the images. Faint objects can be studied with a resolution of 0.05 arcsecond using the ARC telescope. The system will allow fundamentally new observations of objects from planets to distant galaxies.

Baselines of hundreds of meters are needed to study the environment and surfaces of stars or the core of active nuclei. Distributed arrays of telescopes can provide such resolutions using synthesis techniques developed in radio astronomy. Such arrays pose formidable technical and system engineering problems requiring the development of stable telescopes, precision delay lines and correlators stable to nanometers over the short observation periods. A 5- or 6-telescope array is being planned using 0.6-meter telescopes operating in the near infrared.

Edward W. Kolb

The close collaboration between the Department of Astronomy and Astrophysics and the Astrophysics effort at Fermi National Accelerator Laboratory in nearby Batavia, Illinois exploits the close ties between particle physics and cosmology/astrophysics. The major effort of my research is the attempt to understand physical processes that occurred in the very earliest moments of the "Big Bang." In these very early moments the density, energy, and pressure of the universe resembled the conditions obtained in the collisions of particles at high-energy accelerators. The microphysics of the very early universe leaves its imprint on the present large-scale structure of the universe in the form of galaxies, the baryon asymmetry, element abundances, and structure in the cosmic microwave background radiation.

Arieh Königl

The physical processes underlying accretion and outflow phenomena in compact astronomical objects are being studied. These studies bear directly on such issues as star formation and the nature of active galactic nuclei. Since the material attracted by the gravitational pull of the compact object (be it a solar-mass protostar or a supermassive black hole) is typically rotating, it often settles into an ``accretion disk'' through which matter can continue to flow toward the center if there is a suitable mechanism for transporting away its angular momentum. Compact objects are frequently also found to give rise to energetic bipolar outflows, or jets, which propagate supersonically to large distances from the origin. Since the outflows are believed to be powered by the accretion process, one major goal of these investigations is to construct self-consistent disk/jet models and to examine their implications to the observable properties and to the dynamical evolution of young stars and of active galactic nuclei. Additional aspects of accretion disks and jets in these two astrophysical settings are being studied by combining analytical and numerical techniques in magnetohydrodynamics, radiation hydrodynamics, and relativistic gas dynamics, as well as through observations.

Richard G. Kron

Velocities of recession due to the expansion of the Universe (redshifts) for 400 faint galaxies and 130 faint quasars have been measured along four different lines-of-sight, which allow the distribution and other properties of these sources to be studied in those directions. The galaxies are bunched into narrow intervals of redshift, which suggests that aggregations of matter commonly occur on scales of several hundred million light-years. The quasar survey is designed to probe to very faint luminosities and to high redshifts, and can thus provide a more direct observational link between quasars and ordinary galaxies at prior epochs. Supporting work includes a study of galaxies that are unresolved with ground-based telescopes (but can be studied with the Hubble Space Telescope), and a search for faint sources that vary in intensity over a period of a decade-as expected, these are predominantly quasars.

Don Q. Lamb

The focus of my research is the physics of matter and radiation under extreme conditions. Compact objects such as white dwarfs, neutron stars, and black holes provide an astrophysical laboratory for such studies. Their high internal densities enable non-ideal Coulomb solids, heavy nuclei, nuclear matter, and even quark matter to be probed. Hot dense matter is also crucial to an understanding of supernovae. The large gravitational potentials and the strong magnetic fields at the surfaces of these objects produce phenomena ranging from radio pulsars to active galactic nuclei. These phenomena can be used to test our understanding of nuclear reactions, hydrodynamics and shocks, and radiation transfer in magnetoactive and relativistic plasmas in new regimes, as well as to determine the properties, such as mass, radius, and magnetic field, of the compact objects themselves. My current research activities include projects in the following areas: properties of relativistic pair plasmas and hot dense matter; structure and evolution of degenerate dwarfs and neutron stars; supernovae, pulsars; X-ray emission from degenerate dwarfs and neutron stars; X-ray and gamma-ray bursts; and active galactic nuclei.

Stephan Meyer

The properties of the Cosmic Microwave Background Radiation (CMBR) is one of the best observables used to constrain the models of the evolution of the early universe. We are making measurements of both the anisotropy, and the low-frequency absolute temperature of the CMBR.

The absolute experiment is designed to complement the spectrum made by the COBE FIRAS experiment. In some circumstances, the thermal history of the plasma that existed before the production of the CMBR leaves a measurable distortion in the CMBR spectrum at low frequencies that can be detected by this measurement.

Anisotropy experiments have already constrained the magnitude of fluctuations at large scales. These fluctuations are presumably the starting points for the evolution of the structures we see today -- galaxy clusters, galaxies and stars. The current focus of anisotropy experiments at Chicago are to measure the CMBR variations at smaller angular scales. These measurements will determine whether the details of current evolution models are correct because they predict observable effects due to the dynamics of the matter as it evolves.

We are observing with a balloon-borne Medium Scale Anisotropy Measurement (MSAM) which has determined the magnitude of the 0.5-degree fluctuations with high sensitivity. The measurements are consistent with many of the current models and are indicating that the effect of the dynamics may be present.

We are currently building a new gondola called TopHat that will also fly on high-altitude balloons. It will be placed on the top of the balloon where the effects of instrumentation above the gondola are minimized. It will use a relatively new capability, Long Duration Ballooning (LDB) which permits flights as long as 20 days. This instrument will produce a map of the microwave sky and constrain the evolution models as well as determine several of the cosmological parameters that have long eluded precise measurement.

Richard H. Miller

Numerical experiments, carried out on self-consistent, self-gravitating systems by means of fully three-dimensional N-body computer programs, are the best tool available today for studies in the dynamics of galaxies, clusters of galaxies, and star clusters. Relaxation effects are suppressed by using 100,000 to a million particles. The programs are extremely versatile. These experiments play the same part for galaxy dynamics as laboratory experiments do in physics. Dynamics of Galaxies is a beautiful problem in Computational Physics. Beautiful objects (galaxies and star clusters) are studied by means of a beautiful formalism (Hamiltonian mechanics).

Important discoveries have come from this work. These include, among others (1) that the nucleus of a galaxy orbits around the galaxy's mass centroid, which can cause the nucleus to appear slightly off-center or to have a velocity that differs from the rest of the galaxy by tens of km/sec, (2) that galaxies oscillate in normal modes with surprisingly large amplitudes, (3) that the strong contractions evident in galaxy collisions are normal modes of oscillation, (4) that barlike forms are dynamically preferred for rapidly rotating self-consistent stellar systems while the traditional axisymmetric disk-like form is dynamically unstable, and (5) that the gravitational N-body problem is chaotic.

Recent work includes dynamical studies to determine whether a galaxy that forms around a pre-existing supermassive black hole look different from a galaxy that formed without one, and studies to find what physics must be invoked in order that clusters of galaxies may form with rounded central density profiles. Rounded centers have been found by Tyson and his co-workers through observational studies based on gravitationally lensed images. The problem is to find how the cluster profile can be rounded while the galaxies within it have cuspy centers. New experimental methods and techniques must be developed for each of these problems. They are challenging, but new discoveries are likely to follow.

Takeshi Oka

See Department of Chemistry

Angela Olinto

Olinto's interests are in theoretical astrophysics, particle and nuclear astrophysics, and cosmology. Her recent work has focused on cosmological effects of magnetic fields, the internal structure of neutron stars, and the highest energy cosmic rays.

Patrick E. Palmer

My work contains two related themes: star formation and the nature of comets. These themes are related both phenomenologically - both involve study of cold, low density gases -- and at a deeper level -- comets provide the most pristine remaining samples of the material out of which our star, the Sun, formed.

Because of the appearance of a truly great comet, comet Hale-Bopp in 1997, comets have taken up most of my time for the past several years. I participated in many collaborations using optical and radio telescopes around the world to collect data on this comet. Now we are extremely busy analyzing this unique collection of data.

In collaboration with Lewis E. Snyder and J. Veal (U. of Illinois), Imke de Pater and M. Wright (U. C. Berkeley), Michael A'Hearn and L. Woodney (U. of Md.) and others, I used the BIMA array to image both continuum and molecular line emission with a resolution of ~ 10". We discovered emission from HCO+; which, although well known in the interstellar medium, had never before been observed in a comet. We imaged the HCN emission on 13 dates near closest approach, which allowed us to 1) test that the photo-dissociation lifetime of HCN is in fact the accepted one, 2) determine the fractional abundance of HCN (relative to H2O), and 3) study asymmetries in the emission - jets and the location of active regions on the nucleus. In another project, we imaged CS emission on three dates, with very similar goals. We found that the photo-dissociation lifetime of CS was in error by a factor of 10, which has implications for all previous reports of the abundance of CS in comets. We also analyzed 3mm continuum emission images, and found that at this wavelength, the nucleus is not visible because of the extended emission from the dust flowing away from the nucleus.

In another project, with B. Butler (NRAO) and V. Strelnitski (MMO), we searched for H2O maser emission from comet Hale-Bopp. Such emission had been reported from several previous comets, but in many other cases, this emission had been searched for and not found. By searching in such an excellent comet on four different epochs with the VLA, which provided greater sensitivity that any previous search, we hoped to settle the question. We did not see any emission.

I have started (or re-started) several projects on star formation while the comet data is being written up. The first is analysis of excited OH maser emission (observed with the VLA) from several regions of star formation. This emission seems to pick out the most active and youngest regions. Further analysis is continuing.

Recent publications:
"VLA Observations of the Sagittarius D Star-Forming Region", Mehringer, D. M., Goss, W. M., Lis, D. C., Palmer, P., and Menten, K. M. 1998, Ap. J., 493, 274.
"BIMA and VLA Observations of Comet Hale-Bopp at 22 -- 115 GHz", de Pater, Imke, Forster, J. R., Wright, M., Butler, B., Palmer, P., Veal, J. M., A'Hearn, M. A., and Snyder, L. E. 1998, A. J., 116, 987.
"Mosaiced Images and Spectra of J=1--0 HCN and HCO+ Emission From Comet Hale-Bopp (1995 O1)" 1998, Wright, M. C. H., de Pater, I., Forster, J. R., Palmer, P., Snyder, L. E., Veal, J. M., A'Hearn, M. F., Woodney, L. M., Jackson, W. M., Kuan, Y.-J., and Lovell, A. J. 1998, A.J., 116, 3018.

Robert Rosner

R. Rosner and collaborators conduct both theoretical and observational research in solar and stellar astrophysics, more general plasma astrophysics, and fluid dynamics.

In the area of (astrophysical) fluid dynamics and magnetohydrodynamics, we have continued our studies of thermal instabilities in galaxy cluster halos and cooling flows; L. Tao (now at Cambridge University) has studied the effects of turbulent magnetic fields in galaxy cluster halos on the efficacy of thermal conduction, showing that very large suppression of conduction by such magnetic fields is highly unlikely. In the area of thermal convection, we have focused on both Boussinesq and fully compressible convection. In the former area, J. Werne (now at NCAR) has investigated in more detail the nature of "slot convection" at moderate and high Rayleigh numbers. Senior research associates F. Cattaneo and A. Malagoli have continued their work on large-scale simulations of compressible convection, focusing on the problem of penetrative convection.

In the area of magnetohydrodynamics, we have focused on problems related to turbulent magnetic field diffusion and dynamo processes. F. Cattaneo, L. Tao, E.-J. Kim, and collaborators in the UK have studied non-linear (Lorentz) backreaction in the context of so-called "fast" dynamos; L. Tao, Y. Du, R. Rosner, and F. Cattaneo have studied the emergence of fractal structures in surface distributions of magnetic fields immersed in turbulent conducting fluids; and E.-J. Kim, A. Olinto, and R. Rosner have focused on the effects of magnetic fields on the evolution of density perturbations just after the recombination epoch.

Finally, A. Malagoli has continued an ambitious effort to construct a multi-dimensional Godunov scheme for magnetohydrodynamic simulations; recent simulations involving this code include a study of Kelvin-Helmholz instability for a magnetized shear layer (with G. Bodo/Torino and R. Rosner).

At the level of more analytical studies, M. Berger (London) and Rosner have studied the turbulent decay of magnetic fields in the context of mean field theory, focusing on the evolution of magnetic helicity; Z. Musielak (Huntsville), Rosner, R. Stein (Michigan State), and P. Ulmschneider (Heidelberg) have re-investigated the efficacy of sound generation in stellar atmospheres; and Y.Q. Lou and Rosner have studied the reflection of Alfven waves in stratified atmospheres; and Z.E. Musielak (U. Alabama/Huntsville), R. Rosner, P. Gail (Heidelberg), and P. Ulmschneider (Heidelberg) have developed a new methodology for computing wave fluxes along magnetic flux tube waves in stellar convection zones.

In the area of stellar astrophysics, V. Kashyap, R. Rosner, and Professor J. Truran have considered the effects of MACHOs on the diffuse soft X-ray background. We have also used ROSAT observations to constrain models for the coronae of "hybrid stars" (with Y. Kashyap, F.R. Harnden [CfA], A. Maggio [Palermo], G. Micela [Palermo], and S. Sciortino [Palermo]) and other types of giants (R. Rosner, with A. Collura [Palermo], A. Maggio [Palermo], G. Micela [Palermo], S. Sciortino [Palermo], and F.R. Harnden, Jr. [CfA]); and constructed the first self-consistent model for the so-called "dividing lines" separating evolved stars with distinct coronal properties (R. Rosner, with Z.E. Musielak [U. Alabama/Huntsville], F. Cattaneo, R.L. Moore [NASA/Marshall], & S.T. Suess [NASA/Marshall]).

Noel M. Swerdlow

My general field of research is the history of the exact sciences, particularly astronomy, from antiquity through the seventeenth century. In 1998 I published through Princeton University Press The Babylonian Theory of the Planets concerned principally with the derivation of the numerical parameters of the mathematical planetary theory from records of observations of the dates of the heliacal phenomena of the planets, as first and last visibilities. The study also considers the relation of Babylonian observational and mathematical astronomy to celestial divination, which was its principal motivation. I am currently completing a book on Galileo's astronomy and the resulting conflicts with the Church, then a short book on Renaissance astronomy I have been asked to write, and after that I will return to a project begun a few years ago, a more or less comprehensive survey of astronomy in the Renaissance, concentrating on the most important astronomers of the period, Regiomontanus, Copernicus, Tycho, Kepler, and Galileo.

James W. Truran

The focus of my research is the attempt to understand the physical processes that are responsible for the synthesis of the heavy elements observed in nature. This necessarily involves the consideration of a broad range of problems in theoretical nuclear astrophysics. The high temperatures and densities achieved in stellar, nova and supernova environments are entirely compatible with the formation of heavy elements via nuclear processes; the sensitive dependencies of the resulting abundance patterns on the temperature, density, and convective history of the stellar matter and supernova ejecta demand that theoretical calculations of the nucleosynthesis yields must be coupled directly to hydrodynamic models of nova and supernova explosions. In order to view these studies of nucleosynthesis in individual events in perspective, it is further necessary to examination their implications for the composition of the stars and gas in galaxies as a function of time. Such studies of galactic chemical evolution are now increasingly tied to models of galactic dynamical evolution.

My current research activities include projects in the following areas: thermonuclear runaways and the outbursts of the classical novae; X-ray and gamma-ray emission from classical novae; r-process neutron-capture synthesis and nuclear cosmochronology; nucleosynthesis in red giant environments; cosmic ray production of the light elements and galactic chemical evolution; explosive nucleosynthesis in metal deficient stars; the formation and early evolution of globular clusters; the chemical and dynamical evolution of the galactic halo; and thermonuclear reactions at high temperatures and densities.

Michael S. Turner

My research focuses on the application of modern ideas in elementary-particle theory to cosmology and astrophysics. I believe that this approach holds the key to answering the most pressing questions in cosmology. For example, there is reason to believe that the ubiquitous dark matter that holds the Universe together is elementary particles left over from the earliest moments, that the primeval inhomogeneity in the distribution of matter, which was revealed by COBE and which seeded all the structure in the Universe seen today, arose from quantum-mechanical fluctuations occurring during a very early burst of expansion called inflation, and that the existence of ordinary matter resulted from particle interactions in the early Universe that make the proton unstable and do not respect the symmetry between matter and antimatter. By testing these ideas with cosmological data, outer space becomes a window to the earliest moments of creation and to the unification of the forces and particles of Nature.

Over the next decade the search for particle dark matter, the mapping of the distribution of matter in the Universe a few hundred thousand years after the beginning through precision measurements of the cosmic microwave background radiation, and the mapping of structure in the present Universe by determining the positions of millions of galaxies should definitively test these bold ideas. Much of the crucial experimental work is being done by colleagues at Chicago; for example, the Sloan Digital Sky Survey will map the positions of a million galaxies and the DASI, TopHat, MAP, and Python experiments will measure the fine-scale anisotropy of the cosmic microwave background radiation.

Current specific areas of research include: big-bang nucleosynthesis in era of precision cosmology; theoretical aspects of inflationary cosmology; testing the inflationary paradigm; determining the nature of the dark energy that is causing the Universe to accelerate; dark matter and dark-matter detection; dark matter and the formation of structure in the Universe; the origin of the cosmic asymmetry between matter and antimatter; understanding how to use precision measurements of the fine-scale anisotropy of the cosmic microwave background and large-scale structure to probe inflation and fundamental physics; and aspects of axion, neutrino and string cosmology.

Selected Bibliography
1. Spontaneous Creation of Almost Scale-Free Density Perturbations in an Inflationary Universe (J. M. Bardeen, P. J. Steinhardt and M.S. Turner) Physical Review D 28, 679 (1983)
2. Supersymmetric Dark Matter Above the W-Mass (K. Griest, M. Kamionkowski, and M.S. Turner) Physical Review D 41, 3565 (1990)
3. Cosmological Baryon and Lepton Number in the Presence of Electroweak Fermion Number Violation (J.A. Harvey and M.S. Turner) Physical Review D 42, 3344 (1990)
4. The Early Universe (E.W. Kolb and M.S. Turner) (Addison-Wesley, 1990)
5. Constraints from Primordial Nucleosynthesis to the Mass of the Tau Neutrino (E.W. Kolb, M.S. Turner, A. Chakravorty, and D.N. Schramm) Physical Review Letters 67, 533 (1991)
6. Gravitational Waves from First-order Cosmological Phase Transitions (A. Kosowsky, M.S. Turner, and R. Watkins) Physical Review Letters 69, 2026 (1992)
7. Recovering the Inflationary Potential (M.S. Turner) Physical Review D 48, 5539 (1993) (astro-ph/9307035)
8. The Cosmological Constant is Back (L. Krauss and M.S. Turner) General Relativity and Gravitation 27, 1137 (1995) (astro-ph/9504003)
9. Cold Dark Matter (S. Dodelson, E.I. Gates, and M.S. Turner) Science 274, 69 (1996) (astro-ph/9603081)
10. CDM Models with a Smooth Component (M.S. Turner and M. White) Physical Review D (Rapids) 56, R4439 (1997) (astro-ph/9701138)
11. First Results of a High-sensitivity Search for Cosmic Axions (K. van Bibber et al) Physical Review Letters 80}, 2043 (1998) (astro-ph/9801286)
12. Big-bang Nucleosynthesis Enters the Precision Era (D.N. Schramm and M.S. Turner) Reviews of Modern Physics 70, 303 (1998) (astro-ph/9706069)
13. Probing Unstable Massive Neutrinos with Current Cosmic Microwave Background Observations (R.E. Lopez, S. Dodelson, R.J. Scherrer, and M.S. Turner) Physical Review Letters 81, 3075 (1998) (astro-ph/9806116)
14. Large-scale Structure from Quantum Fluctuations in the Early Universe (M.S. Turner) Phil. Trans. R. Soc. Lond. (1999) (astro-ph/9808149)
15. Cosmology Solved? Quite Possibly (M.S. Turner) Pub. Astron. Soc. Pac. 111, 264 (1999) (astro-ph/9811364)
16. Cosmology at the Millennium (M.S. Turner and J.A. Tyson) Reviews of Modern Physics 71, S145 (1999) (astro-ph/9901113)
17. Cosmic Rosetta Stone (C. Bennett, M.S. Turner, and M. White) Physics Today, November 1997, p. 32
18. Inner Space & Outer Space (M.S. Turner) Beamline, Fall 1997, p. 2
19. Sharpening the Predictions of Big-bang Nucleosynthesis (S. Burles, K. Nollett, J. Truran and M.S. Turner) Physical Review Letters, 82 (1999) (astro-ph/9901157)
20. Prospects for Probing the Dark-energy via Supernova Distance Measurements (D. Huterer and M.S. Turner) Physical Review Letters 82, (1999) (astro-ph/9808133)
21. Dark Matter and Dark Energy in the Universe (M.S. Turner) Physica Scripta, in press (1999) (astro-ph/9901109)
22. Constraining Dark Energy with SNe Ia and Large-scale Structure (S. Perlmutter, M.S. Turner, and M. White) Physical Review Letters 82, 1999 (astro-ph/9901052)

Peter O. Vandervoort

I am particularly interested in theoretical studies of the structures and the dynamics of galaxies. My purpose is to understand the forms and internal motions of galaxies as the consequences of the orbital motions of their constituent stars in response to the mutual gravitational attractions of those stars. This is accomplished through the construction of self-consistent, equilibrium models of galaxies. Stellar orbits in the prevailing gravitational field are the "building blocks" of such models, and their study is a central part of the subject. If a galaxy in equilibrium is unstable with respect to some small perturbation, then it cannot continue to exist in that equilibrium state. Therefore, my work includes studies of the oscillations and the stability of galaxies with a view to identifying those theoretical models which can provide viable representations of real galaxies. This research makes use of methods of mathematical analysis and numerical n-body calculations.

Donald G. York

Studies of the interstellar medium and intergalactic medium are underway using Earth-orbiting and ground-based spectrographs. For gas near the Sun, absorption lines of interstellar gas in stellar spectra are used to study abundances, ionization states, phases of the medium and the make-up of interstellar grains. The locations in space and the masses of interstellar clouds are being determined.

Intergalactic gas is used to probe and map halos of galaxies to determine the distribution of light elements that may be products of primordial nucleosynthesis, and to study the temperature, pressure, and element evolution in the gas between the galaxies. Studies of such absorption lines in spectra of distant QSOs aid in discovering high redshift galaxies. The build-up of the elements through continuing nucleosynthesis is being used to chart galaxy evolution early in the history of the Universe.

For the next few years, the primary instruments used will be the FUSE (Far Ultraviolet Spectroscopic Explorer), to observe hot UV objects to about 14th magnitude; the ARC 3.5 meter telescope at Apache Point Observatory, with an echelle spectrograph and a Fabry-Perot imager; the 2.5 meter telescope (e) of the Sloan Digital Sky Survey (to construct a complete atlas of intergalactic absorption lines); and the Hubble Space Telescope STIS spectrograph, for studies of interstellar lines down to the FUSE magnitude limit.