PARTICLE ASTROPHYSICS & COSMOLOGY
PRINCIPAL INVESTIGATOR: GEORGE F. SMOOT

Other Group Members:

* Julian Borrill, Post Doctoral Fellow Physics
* Andrew Jaffe, Post Doctoral Fellow Physics
* Giovani de Amici, Associate Research Physicist
* Bruce Grossan, Assistant Research Physicist
* Eric Gawiser, Graduate Student, UCB Physics Department (shared with Joe Silk)
* Henrik Nordberg, Graduate Student, Physics Department, Lund University
* Bahman Rabii, Graduate Student, UCB Physics Department
* Paula Platania, Visiting Research Physicist
* Mike Leung, undergraduate, Physics Department
* Jon Aymon, software/data analyst
* John Gibson, electronic engineer
* Vanessa Arce, Admistrative Assistant
* Willi Chinowsky, Research Physicist

1. COSMOLOGY with the Cosmic Background Radiation

Measurements of The Cosmic Background Radiation (CMB) provide important information about physical processes in the Universe from soon after the Big Bang until the present. In the Big Bang model, which has now become the standard model of cosmology, the CMB last interacted significantly with matter at a time roughly one third of million years after the start of the universal expansion and about 10-15 billion years before the present epoch. The CMB carries with it the information about that interaction and to a lesser degree the effects occurring during its journey to us. Its angular distribution is related to the distribution of matter and energy in the early Universe; its spectrum provides information about processes involving the release of energy.

During the past year we have continued our investigations using the cosmic microwave background (CMB) radiation as a probe of cosmology.

COBE
The COBE satellite continues to provide additional new results and acts as a test bed for new techniques and algorithms in the 7th year past its launch and 5 years since its discover of CMB anisotropies. Its data remain in many ways the best CMB anisotropy data.

With COBE we have made major advances in measuring the large angular scale distribution of the CMB. The major products from COBE include a series of maps of the full sky in the 1 micrometer to 1 centimeter wavelength range. COBE was operated for four years, providing high quality data from about half its sensors. The other half of the sensors were turned off when the liquid helium coolant was exhausted near the end of the first year.

The processing and analysis of the data from COBE has provided high quality maps of the microwave and infrared sky, and their subsequent analysis has yielded significant new cosmological and astrophysical information. Of the three instruments aboard COBE, Dr. Smoot is principal investigator of the Differential Microwave Radiometer (DMR) experiment. The announcement of the detection of anisotropies by Dr. Smoot has been followed by numerous interpretive papers by members of the COBE/DMR collaboration and by outside researchers.

The observed anisotropies have been a powerful cosmological tool providing information on the initial conditions leading to the formation of large scale structure such as galaxies and clusters of galaxies. It has also let us determine important cosmological parameters such as the dynamics, geometry and topology of the Universe.

Our group has continued the analysis of the old and new data. Public release of the resulting skymaps occurred for the first year's observations in June 1993. The first two years worth of data were released in June, 1994. The full four-year data and first results were made public in January 1996. The COBE project comes to its official end at the end of this year (1997); however, we can anticipate that its data and experience will continue to play an important role in cosmology for a few more years.

Figure 1. Full sky map of the CMB anisotropies from the COBE DMR.

Max Planck Surveyor
We, as part of a larger collaboration, have completed the Phase A study of the third generation CMB anisotropy mission, the European Space Agency (ESA) M3 mission: Max Planck Surveyor satellite. Launch is anticipated circa 2005.

MAXIMA/BOOMERANG Balloon-borne Instruments
We - a collaboration with Professors Paul Richards at SSL, Andrew Lange (CalTech), and Paola deBernardis (Rome) - have built and tested a pair of new generation balloon-borne gondolas and instruments MAXIMA & BOOMERANG . BOOMERANG had its first and successful flight in early September 1997. We anticipate flights of MAXIMA in the spring and summer and a long-duration flight of BOOMERANG from Antarctica in the coming season.

Foreground Emissions
We have reached the point where the emission from the galaxy is beginning to limit the interpretation of the data. Thus we have embarked on a program to improve our understanding and modeling of this emission for both the cosmological interpretations and the study of our galaxy. This involves both a project to make low frequency radio maps of the sky dubbed the Galactic Emission Mapping (GEM) project and an effort to model and find means to remove Galactic and extragalactic foregrounds from the data.
2. Ultra-High Energy Neutrino Astronomy

In collaboration with Hank Crawford (SSL), Willi Chinowsky, Dave Nygren, and Bob Stokstad we have been working on the development of a km-scale ultra-high energy neutrino detector. This work has led us to a collaboration with the AMANDA project.
6. Milestones

* Completion of Phas A Study and Selection of Planck Surveyor
* Award of NERSC supercomputer time and resources
* Award of LSTA to study

7. Graduate Students Supported

* Bahman Rabii, Physics Department
* Henrik Nordberg, Physics Department, Lund University

8. Refereed Publications

* E. Gawiser and G.F. Smoot. Contribution of Extragalactic Infrared Sources to CMB Foreground Anisotropy. astro-ph/9603121 The Astrophysical Journal Letters 480, L1-4 (1997).
* G.F. Smoot and D. Scott. Cosmic Background Radiation. astro-ph/9603157, Reviews of Particle Properties, PRD 54, 118 (1996).
* G. Smoot, ³The CMB Anisotropy Experiments,² astro-ph/9705135, May 18,1997.
* G. Smoot, ³The CMB Spectrum,² astro-ph/9705101 v2, May 18, 1997 [paper given at Strasbourg NATO School.]
* S.T. Tanaka, A.C. Clapp, M.F. Devlin, N. Figueiredo, J.O. Gundersen, S. Hanany, V.V. Hristov, A.E. Lange, M.A. Lim, P.M. Lubin, P.R. Meinhold, P.L. Richards, G.F. Smoot, and J. Staren. Measurements of Anisotropy in the Cosmic Microwave Background Radiation at 00.5 Scales near the Stars HR5127 and Phi Herculis. astro-ph/9512067 The Astrophysical Journal Letters 468, L81-84 (1996).
* G. Hinshaw, A.J. Banday, C.L. Bennett, K.M. Gorski, A. Kogut, G.F. Smoot and E.L. Wright. Band Power Spectra in the COBE-DMR Four-Year Anistropy Maps. COBE preprint 96-04, astro-ph/9601058, The Astrophysical Journal Letters 464, L17-20 (1996).
* E.L. Wright, C.L. Bennett, K. Gorski, G. Hinshaw and G.F. Smoot. Angular Power Spectrum of the Microwave Background Anistropy Seen by the COBE Differential Microwave Radiometer. COBE preprint 96-05, The Astrophysical Journal Letters 464, L21-24 (1996).
* A. Kogut, G. Hinshaw, A.J. Banday, C.L. Bennett, K. Gorski, G.F. Smoot, and E.L. Wright. Microwave Emission at High Galactic Latitudes in the Four-Year DMR Sky Maps. COBE preprint 96-02, astro-ph/9601060, The Astrophysical Journal Letters 464, L5-9 (1996).
* G. Hinshaw, A.J. Banday, C.L. Bennett, K.M. Gorski, A. Kogut, C.H. Lineweaver, G.F. Smoot and E.L. Wright. Two-Point Correlations in the COBE DMR Four-Year Anisotropy Maps. COBE preprint 96-06, The Astrophysical Journal Letters 464, L25-28 (1996).
* A. Kogut, A.J. Banday, C.L. Bennett, K. Gorski, G. Hinshaw, G.F. Smoot, and E.L. Wright. Tests for Non-Gaussian Statistics in the DMR Four-Year Sky Maps. COBE preprint 96-07, The Astrophysical Journal Letters 464, L29-33 (1996).
* K.M. Gorski, A.J. Banday, C.L. Bennett, G. Hinshaw, A. Kogut, G.F. Smoot, and E.L. Wright. Power Spectrum of Primordial Inhomogeneity Determined from the Four-Year COBE DMR Sky Maps. COBE preprint 96-03, The Astrophysical Journal Letters 464, L11-15 (1996).
* A.J. Banday, K.M. Gorski, C.L. Bennett, G. Hinshaw, A. Kogut, and G.F. Smoot. Non-Cosmological Signal Contributions to the COBE DMR Four-Year Sky Maps. COBE preprint 96-08, The Astrophysical Journal Letters 468, L85-89 (1996).
* A.J. Banday, K.M. Gorski, C.L. Bennett, G. Hinshaw, A. Kogut, and G.F. Smoot. RMS Anisotropy in the COBE DMR Four-Year Sky Maps. COBE preprint 96-09, The Astrophysical Journal 475, 393-398 (1997).
* A. Kogut, A.J. Banday, C.L. Bennett, K.M. Gorski, G. Hinshaw, P.D. Jackson, P. Keegstra, C. Lineweaver, G.F. Smoot, L. Tenorio, and E.L. Wright. Calibration and Systematic Error Analysis For the COBE DMR Four-Year Sky Maps. COBE preprint 96-10, The Astrophysical Journal 470, 653-673 (1996).
* C.L. Bennett, A. Banday, K.M. Gorski, G. Hinshaw, P. Jackson, P. Keegstra, A. Kogut, G.F. Smoot, D.T. Wilkinson, and E.L. Wright. Four-Year COBE DMR Cosmic Microwave Background Observations: Maps and Basic Results. COBE preprint 96-01, The Astrophysical Journal Letters 464, L1-4 (1996).
* G.F. Smoot. Of Cosmic Background Anisotropies. Examining the Big Bang and Diffuse Background Radiations, 31-44, M. Kafatos & Y. Kondo (eds.), IAU, (1996)
* G.F. Smoot. The Cosmic Background Radiation. Particle and Nuclear Astrophysics and Cosmology in the Next Millennium, Proceedings of the 1994 Snowmass Summer Study, edited by E.W. Kolb and R.D. Peccei, World Scientific , astro-ph/9603157 (1995)
* C.H. Lineweaver, L. Tenorio, G.F. Smoot, P. Keegstra, A.J. Banday, and P. Lubin. The Dipole Observed in the COBE DMR Four-Year Data. astro-ph/9601151, by The Astrophysical Journal 470, 38-42 (1996).
* S. Torres, V. Canon, R. Casasa, A. Umana, C. Tello, T. Viellela, M. Bersanelli, M. Bensadoun, G. De Amici, M. Limon, G.F. Smoot, and C. Witebsky. The GEM Project: An International Collaboration to Survey Galactic Radiation Emission. Proceedings from UN/ESA Workshop Basic Space Sciences: From Small Telescopes to Space Missions, astro-ph/9605060, Astrophysics Space Science, 240, 225 (1996)
* A. Kogut, M. Bersanelli, D. Maino, G. De Amici, and G.F. Smoot. Polar Measurements of Atmospheric Continuum Microwave Emission, Antarctic Journal of the United States, 29 329 (1996).
* D. Saez, E. Holtmann, and G.F. Smoot. Small Angular Scale Simulations of the Microwave Sky. astro-ph/960614, The Astrophysical Journal 473, 1-6 (1996).
* M.A. Lim, A.C. Clapp, M.J. Devlin, N. Figueiredo, J.O. Gunderson, S. Hanany, V.V. Hristov, A.E. Lange, P.M. Lubin, P.R. Meinhold, P.L. Richards, J.W. Staren, G.F. Smoot, and S.T. Tanaka. The Second Measurement of Anisotropy in the Cosmic Microwave Background Radiation at 00.5 Scales Near the Star Mu Pegasi, The Astrophysical Journal Letters 469, L69-72 (1996).
* S. Odenwald, J. Newmark, G.F. Smoot. A Study of External Galaxies Detected by the COBE Diffuse Infared Background Experiment.. astro-ph/9610238, accepted by The Astrophysical Journal (1997)
* G.F. Smoot. The Status of CMB Observations. Cosmological Constant and the Evolution of the Universe, edited by K. Sato, T. Suginohara, and N. Sugiyama, Universal Academy Press, Inc., Tokyo (1996)
* P. Platania, M. Bensadoun, M. Bersanelli, G. De Amici, A. Kogut, S. Levin, D. Maino, and G.F. Smoot . A Determination of the Spectral Index of Galactic Synchrotron Emission in the 1-10 GHz Range. astro-ph/9707252, The Astrophysical Journal (1997) Accepted

9. Other Publications

* G.F. Smoot. Introduction and Overview: CMB Sessions. astro-ph/9703165, Texas Meeting on Relativistic Astrophysics, Dec. 1996, Ed. Olinta
* A. de Oliveira-Costa, G.F. Smoot, and A. Starobinsky. Constraining Topology with the CMB. astro-ph/9705125, Proceedings from the 31st Recontres de Moriond: Microwave Background Anisotropies, Les Arcs, France, March 16-23, 1996, Moriond Astrophysics 85-90 (1996) Report
* G.F. Smoot. CMB Experiment Baseline Determination by Minimizing Pixel Observations Dispersion. astro-ph/9704193, COBE-5047-REV, The Astrophysical Journal (1997) Submitted