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T. Dahlen, L. -G. Strolger, A. G. Riess, B. Mobasher (STScI), R. Chary, C. J. Conselice (CalTech), H. C. Ferguson, A. S. Fruchter, M. Giavalisco, M. Livio (STScI), P. Madau (UCSC), N. Panagia (STScI), J. L. Tonry (U. Hawaii), GOODS Team
The Great Observatories Deep Origins Survey (GOODS) discovered a total of 42 supernovae (SNe) with mean redshift z~0.8 in CDF-S and HDF-N. Using all available information, including redshifts, light curve decline, magnitudes and colors, we classify 16 of these as core collapse SNe (type II and Ib/c), with the remaining being type Ia SNe (Strolger et al. 2003, in preparation).
We calculate the rate of core collapse SNe at redshifts z~0.3 and z~0.7 (given as the number of exploding SNe per year per cubic Mpc in comoving units). We find that the rates at these redshifts are significantly higher than the rate measured locally. As core collapse SNe originate from short-lived massive progenitor stars, their rate provides an independent method for estimating the cosmic star formation rate. The steep increase with redshift in the core collapse SN rate is consistent with the increase (by a factor ~10) in the star formation rate to redshift z~1 found by independent measurements (e.g., UV-luminosity densities).
Rates of Ia SNe have previously been measured to redshifts z~0.5. While the rates at z~0.5 were somewhat higher than local rates, these measurements are still consistent with a flat SN Ia rate in the redshift range probed. Using our unique sample of Ia SNe, we estimate the SN Ia rate to z~2. We find a rate at z~1 that is clearly higher than previous measurements at lower redshift, seemingly inconsistent with a constant rate over the redshift range 0 < z < 1. At higher redshifts (z > 1), we find that the SN Ia rate is constant or slightly decreasing.
The author(s) of this abstract have provided an email address for comments about the abstract: dahlen@stsci.edu
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.