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K. Krisciunas (NDU), N. B. Suntzeff (CTIO), P. Candia (Gemini)
Over the past 10 years Type Ia SNe have become the single most important extragalactic distance calibrator for galaxies with redshifts greater than 0.01. Because relatively few SNe are discovered prior to their optical maxima, and because the IR maxima typically occur 3 days before the time of B-band maximum, to measure their maximum magnitudes most accurately requires taking data as soon as the SNe are discovered. SMARTS has allowed us to procure optical and IR imagery within hours of receiving word of a promising SN candidate. Primarily using data obtained with the dual optical/IR camera ANDICAM, along with data from the Las Campanas Observatory, we have been able to devise light curve templates of Type Ia SNe within 10 days of the IR maxima. In the optical bands these objects are standardizable candles, exhibiting absolute magnitudes at maximum which are a function of the post-maximum rate of decline. In the near-IR bands, however, they have essentially the same absolute magnitudes for a wide range of optical decline rates. Thus, they are essentially standard candles in the near-IR. Given that interstellar extinction is an order of magnitude less in the near-IR compared to the optical, we have been able to eliminate any serious systematic errors attributable to host galaxy and Galactic extinction. We find a scatter of ± 0.15 mag in the Hubble diagrams of nearby Type Ia SNe. Thanks to SMARTS we have the best optical and IR light curves of a (rare) subluminous, fast declining Type Ia SN obtained since 1986. We will show some results from our ongoing SN research.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.