Project Summary

Project Summary

"This material is based upon work supported by the National Science Foundation under
Grant No. 0607438"

The apparent detection of an accelerating universe is of profound significance for physics. A gravity-dominated universe should be decelerating. Results to the contrary have implications for the geometry of spacetime and suggest a new form of ''dark energy'' as a major constituent of the universe. But these profound implications depend critically on the measurements and our understanding of the light curves of Type Ia supernovae. Specifically, the reality of the accelerating universe remains controversial because of the possible existence of systematic errors due to poorly-understood 1) photometric systems, 2) reddening corrections, and 3) evolutionary effects. It is therefore an assumption, not yet a firmly-established fact, that the peak luminosities of the Type Ia events can be universally converted to accurate luminosity distances with equal confidence today as at look-back times of 4-10 Gyrs.

Fortunately, these concerns can be fully addressed through the comprehensive study of both Type Ia and II Supernovae in the local (z < 0.07) universe. We therefore propose to embark on a long-term program, the Carnegie Supernova Project (CSP), with the goal of obtaining exceedingly-well calibrated optical/near-infrared light curves and optical spectroscopy of over 200 Type~Ia and Type~II supernovae. The CSP will take advantage of the unique resources available to us at the Las Campanas Observatory (LCO). We have guaranteed access to large numbers of nights (300 per year) on the Swope 1-m and the du Pont 2.5-m telescopes, with high-performance CCD and IR cameras, and CCD spectrographs. In addition to providing gap-free light curves covering the near-UV to the near-IR (UBVRIYJH), we will have the means to obtain optical spectrophotometry at approximately weekly intervals

The immediate tangible result of this effort will be a fundamental dataset for both Type Ia and II supernovae of light curves in a well-understood photometric system, and complementary spectrophotometry which will be put into the public domain via the NASA/IPAC Extragalactic Database (NED). The dataset for the Type Ia events will allow us to verify and/or improve extinction corrections and get a much better handle on evolutionary effects due to age and metallicity. The data for the Type II supernovae will be used to establish and refine precise techniques for obtaining distances to these objects, thereby providing a completely independent check on the Type~Ia results. In addition, we will be able to explore the use of both supernova types for studies of local galaxy flows and the convergence depth. Ultimately, both datasets will serve as a reference for observations of distant (0.3-0.5) supernovae which we shall obtain in coming years with the Magellan telescopes in order to reexamine the evidence that the universe is accelerating.

The CSP will be observationally intensive, requiring many nights of telescope time, as well as extensive data reduction, analysis, and interpretation. To ensure that we will have sufficient human resources to complete the project in a timely way, we will establish a mentoring program for undergraduate and graduate-level students from within a broad and diverse pool of young people within California, and at the Univerities of Arizona, Toronto, and Chile. These people, together with the postdocs involved in this endeavor, will be involved in front-line research using first-class facilities, and will thus be afforded a unique learning more....